When we first started thinking about our vanlife electrical system and buying our components, we had a lot of questions. We researched online, read other van build blogs and forum posts, and watched Youtube videos. Some were very helpful, but many left us with a swirl of even more questions.

We were learning a lot about circuits and electrical systems, but we were also overwhelmed by all the new knowledge coming at us from all directions. Electrical is such a vital part of any van build, and we wanted to get it right.

We longed for a resource that told us: Buy this. Connect it like this. Here’s a diagram.

This post is an attempt to make such a resource.

In this post, we go over exactly what we bought, exactly how we connected everything, and we even have pictures and diagrams (yay)!

For those of you interested in further reading, we also include links to blog posts and other resources that helped us out along the way.

We want this post to be as accurate and helpful as possible, so if we get something wrong or you want us to clear something up, let us know in the comments!

Obligatory Disclaimer: This post describes what we did with our own system based on our own research, and we hope you’ll find it helpful. That said, we are NOT ELECTRICIANS. Working with electricity in any form can be dangerous. It’s always a good idea to read the manuals for all of your components and consult with a licensed electrician before performing any electrical work.

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Mega List of Everything We Used in Our Electrical Install

all the electrical components for our van build
All of our components laid out. The Renogy charge controller looks a bit different than the current model, but the function and installation are the same.

Main Components

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Lights, Dimmers, and Outlets

Wiring and Connectors

Fuses and Cutoff Switches

If you buy a premium solar kit from Renogy, it should come with two 30A/40A ANL fuses/holders, as well as the MC4 inline fuse/holder. You may still need additional ANL fuses for components that require a larger fuse, like your inverter or battery isolator.

Essential Tools

How to Charge Your Batteries While Driving

There’s one more component that we’ve discovered is vital to have on the road: a smart battery isolator.

We have the Keyline Chargers 140-Amp Smart Isolator in our van, and it has worked flawlessly for us.

Note: If you have a newer vehicle or are trying to charge a LiFePO4 battery bank, you will need a DC-DC battery charger like this one from Renogy (make sure to use the coupon code GnomadHome at checkout for 10% off your purchase).

A smart battery isolator allows you to charge your auxiliary batteries from your vehicle’s alternator while driving. This is a great supplement to solar panels, especially if you’re spending time in overcast or heavily forested environments where you don’t get as much sun.

Budget Note

If you only have a few hundred dollars to spend on your electrical system, we recommend starting with a good battery, a smart isolator, and an inverter. You can always add solar later.

Check out this detailed post for more information on battery isolators, what kind to get, and how to install one.

What Does All This Stuff Do?

That’s a pretty intense list. But don’t worry, it’s really not all that complicated. Let’s break it down from a bird’s eye view.

how solar power works for van life

The Sun
It all starts with the sun. The sun not only gives us life, it also constantly beams energy to us here on Earth. Using science, we can convert this energy into electricity to power vanlife!

Solar Panels
Solar panels absorb light from the sun, convert it into electricity, and send it on to the charge controller.

Charge Controller
The charge controller regulates the flow of electricity from the solar panels and uses it to charge your batteries.

Batteries
The batteries we use store electricity at 12-Volt DC (direct current), which can power your lights, exhaust fan, fridge, USB/cigarette lighter outlets, and anything else that runs on DC. In our system, the electricity is fed from the batteries back to the charge controller, which then distributes it outward.

Inverter
If you want to power something like a computer or other complex electronics that require a 3-pronged wall outlet, you’ll also need an inverter, which converts 12-Volt DC to 110-Volt AC (alternating current). This is connected directly to the battery.

That’s basically what’s going on in a 12-Volt van solar power electrical system. Everything else just connects the dots.

How Much Electricity Do You Need?

It’s a good idea to think about how much electricity you’ll use when deciding how many solar panels you need and how big your batteries should be. This can get a bit complicated, especially since there’s a lot you just don’t know about your usage if you’ve never lived in a van before.

But, if you want to make sure you have enough electricity to meet your daily usage while also not paying for more than you need, then going through the exercise of sizing your system is the best thing to do.

How to Size Your System in 3 Easy Steps

Step 1: Calculate the amount of electricity you plan on using in Watt-hours (Wh).

This sounds a bit scary, but it’s actually pretty easy.

First, list out all of the devices/appliances/components you plan on using, along with the amount of Watts each of them draws (this information should be easily available in the component’s instruction manual, or on the internet).

Next, calculate how many hours you plan on using each component. Multiple the Watts by the hours and you have Watt-hours!

Watts x Hours = Wh

So, if your lights use 5 watts and you have them on for 5 hours each day, their power consumption is 25 Wh per day (5W x 5h = 25Wh).

Step 2: Determine the amount of battery capacity you need.

For this example, let’s pretend all your electrical components use 1200 Wh each day.

Battery capacity is measured in amp-hours (ah), so to figure out how big your battery needs to be, convert the 1200 Wh of power consumption into ah by dividing by the system voltage (12V).

1200 Wh / 12V = 100ah.

Based on this calculation, you would need 100ah of battery. But this also depends on the type of battery that you have.

You see, most types of batteries shouldn’t be depleted below about 50% (this goes for regular flooded-lead-acid, AGM, and gel batteries). If these batteries below about 50% you risk shortening its lifespan and/or damaging them. So in reality, the usable capacity of these types of batteries is about half (i.e. 100ah battery = 50ah of usable capacity).

The exception here is LiFePO4 (lithium iron phosphate) batteries. These batteries are more expensive than regular batteries, but you can deplete them 100% (they’re also lighter, safer, and last longer than regular batteries).

So how much battery capacity do you need to accommodate 100ah of usage per day?

  • Regular batteries (FLA, AGM, or Gel): 200ah of battery capacity will cover 100ah of usage, since you never want to deplete these batteries below 50%.
  • LiFePO4 batteries (lithium iron phosphate): 100ah of battery capacity will cover 100ah of usage, since these batteries can be depleted 100%.

Of course, these above numbers assume that you’re dealing with perfect charging conditions and that you never go over 100ah of usage. Reality always ends up a bit different, so if you have the budget it’s a good idea to add in some cushion.

Step 3: Figure out how many solar panels you need to fully charge your batteries each day.

Solar panels are in watts, so we’ll again use our 1200 watts of power consumption. Let’s divide that by the average amount of full sunlight per day (say, 5 hours) to get the amount of solar panels we need.

1200 Wh / 5 hours = 240 Watts. So, 240 Watts of solar panels should, in theory, fully charge your batteries each day and accommodate your power consumption.

Except that it never works that way. There’s shade, and clouds, and less sun in winter, and days where you consume more power than others. Something like three 100-watt panels would be a much safer bet.

Budget-Based System Sizing

Sizing your system appropriately can be challenging, especially if you’ve never lived in a van before. There’s just a lot you won’t know about your real-world usage, and a lot you won’t be able to foresee before you hit the road.

Another method is taking a budget-based approach to your electrical system, and adding capacity as-needed.

If you have a barebones budget, you don’t need a huge, expensive solar setup. But if you can afford it, having a large system will make your life easier and means fewer compromises in your electrical usage.

Here are the main components we recommend for different budget levels:

Barebones Budget

If you have a tight budget, starting off with a good inverter, a battery, and a battery isolator should meet very basic electrical needs (charging phones/computers, some lights). You can always add on solar capabilities later if you need to.

Midrange Budget

This midrange setup gets you started on the right foot, with more battery capacity and 200-watts of solar. This setup is completely expandable, so you can add more panels later if you need to.

Higher Budget

ImageQty.ComponentCheck Price
1Renogy 400-Watt MPPT Solar Kit
Enter coupon code GnomadHome for 10% off at Renogy.com
RenogyAmazon
VMAX SLR155 AGM 12V 155ah Deep Cycle SLA Rechargeable Battery for Solar and Golf, Pv Solar Panels, Smart Chargers, Wind Turbine and Inverters2VMAX 155-Ah AGM Battery (1-pack)
OR buy the 2-pack instead
1-Pack2-Pack
Xantrex 806-1220 PROwatt SW 2000 Inverter - 1800W, True Sine Wave1Xantrex PROwatt SW 2000-watt InverterAmazon
1Renogy 60A DC-DC Charger
Enter coupon code GnomadHome for 10% off at Renogy.com
RenogyAmazon

If your budget allows, a system this size should cover most electrical needs (unless you’re trying to run an AC or electric heater). Over 300Ah of battery capacity, DC-DC battery charger, 2000W inverter, and 400-watts of solar mean you’ll never have to worry about plugging in!

Highest Budget

ImageQty.ComponentCheck Price
1Renogy 400-Watt MPPT Solar Kit
Enter coupon code GnomadHome for 10% off at Renogy.com
RenogyAmazon
Battle Born LiFePO4 Deep Cycle Battery - 100Ah 12v with Built-in BMS - 3000-5000 Deep Cycle Rechargeable Battery - Perfect for RV/Camper, Marine, Overland/Van, and Off Grid Applications2Battleborn 100ah LiFePO4 BatteryAmazon
1Renogy 2000W Pure Sine Inverter Charger
Enter coupon code GnomadHome for 10% off at Renogy.com
RenogyAmazon
1Renogy 60A DC-DC Charger
Enter coupon code GnomadHome for 10% off at Renogy.com
RenogyAmazon

Top of the line (and better-performing) LiFePO4 batteries add a serious upgrade here, and the 2000W inverter charger allows you to plug in as needed (which can come in handy in a pinch).

Choosing Solar Panels and Batteries

Now that you know what size system you need, it’s time to select the actual components.

What We Went With

We decided to go with Renogy’s 400-watt solar kit with 40A MPPT charge controller, and paired it with two VMAX 155ah batteries (for 310ah of total capacity).

[fl_builder_insert_layout id=”3006013″]

Since we didn’t know enough about what our electricity needs would be, we had a tough time calculating the exact size that our system needed to be. From watching Youtube videos and reading blogs, it seemed like many vandwellers just barely scrape by with two 100-watt solar panels, so we decided to go with the biggest system we could afford.

We were only able to fit three of the panels on our van’s roof, but we’ve got the fourth stashed under the bed.

We built a foldout PVC frame for this “extra” panel so we can prop it up and plug it in when needed. This lets us park in the shade on really hot days while still charging our batteries from the sun.

Is our system too big? We don’t think so.

Having this much solar allows us to be 100% off-grid, and we rarely have to worry too much about our power consumption. We’ve met people on the road with smaller systems that regularly worry about making sure they have enough juice to keep their fridge running.

And even with a system this big, we have run low on juice in certain scenarios. If we’re in overcast climates or heavily forested areas (or both) for more than five days or so, and if we’re staying in one place and not driving much, then our batteries start to get down to the 12.0V-12.2V range in the morning. But because of our system size, we can boondock longer in the same spot, in all weather and environments, and still do everything we need to do.

Can you get by with less? Absolutely.

If you’re tighter on funds, Renogy’s 200-watt kit paired with a smart battery isolator is a great place to start. You can always add more panels later.

Whatever you go with, we recommend getting an MPPT charge controller instead of a PWM controller. MPPT controllers are able to squeeze higher efficiency from your solar panels. They’re supposedly up to 25-30% more efficient than PWM controllers. MPPT controllers are more expensive up front, but they’ll allow you to stretch your system much further.

Basic Circuitry: What You Need to Know

Going too deep into basic electronics is beyond the scope of this post, but it definitely helps to visualize how a simple circuit looks when designing your system.

Here’s a diagram of a basic DC circuit:

DC circuit-diagram

Closing the switch completes the circuit and allows electricity to flow between the battery and the lights. One common analogy used here is that of a water pipe. If there’s a break in the pipe, water won’t be able to flow.

A fuse is an intentional weak point in a circuit. It’s there for safety. If too much current flows through the circuit, the fuse will “blow” and break the circuit.

“Grounding” in van life electrical is a connection to the vehicle’s chassis. This is also for safety. In our install, we grounded the battery and the inverter.

Designing Our System (With an Awesome Wiring Diagram!)

In designing our system, we leaned heavily on wiring diagrams we found on the internet, particularly the one in this post by Van Dog Traveller (his ebook has even more detailed diagrams).

But all the diagrams we found gave us a lot of partial information or only halfway applied to our system, and led to some confusion on our part.

After all of our research, we couldn’t find an all-encompassing diagram that showed us exactly how everything in our system fit together. So we made one.

diy-campervan-build-electrical-solar-system-diagram-edited_5.01.18

We highly recommend diagramming your system so you know exactly how everything is supposed to connect. Just drawing it out really helps you think it through and get it straight in your head.

Making Sure You Have the Right Size Wires and Fuses

This can be a bit confusing if you’re new to electrical work. But it’s important to get it right if you don’t want to deal with any electrical or safety issues down the road.

Below, we break down exactly how to calculate the wire sizes you need, and give you some tips on selecting the right fuses for your circuits.

Choosing the Correct Wire Sizes

Ancor Marine Grade Primary Wire and Battery Cable (Red, 100 Feet, 14 AWG)

Choosing proper wire sizes is an important step in any electrical install. If your wires are too thin, it can be a significant safety hazard. If your wires are too thick, you’ll be spending more than you need and your wiring will be harder to work with.

Note: In the United States, wire size is measured in American Wire Gauge (or AWG). AWG gauges may be different than wire gauges used in other countries. Since we are in the US, we used wires measured in AWG for our electrical install.

The size wire that you choose should be based on the amount of current going through the wire and the length of the wire run. You want to use a wire size that’s thick enough to safely handle the electrical current without experiencing too much voltage drop.

How do you figure out the max current that will be going through your wires?

Your lights, appliances, and other electronics should have their max current available in their technical specifications.

For DC appliances this should be listed in amps (max amperage). If your component specs lists this in watts, divide that number by the system voltage (so divide by 12 for a 12V DC system).

How do you figure out the length of your wire run?

First, you’ll need to measure the distance the wiring is going to travel. Then double it.

What?! Double it?! Yup. When calculating wire sizing for DC systems, the wire length refers to the total length of both the positive and negative wire.

So, if you’re wiring an outlet that will be 5 feet from your fuse box, your wire length is actually 10 feet – 5 for the positive wire, and another 5 for the negative wire to complete the circuit.

Okay, so now that I know my max current and wire length, how do I figure out what wire size I need?

Blue Sea Systems has an awesome “Circuit Wizard” calculator on their website that can help you determine the proper wire size for what you need.

Simply enter the system voltage, the max current, and the total wire length. The calculator will spit out the recommended wire gauge for you:

blue sea systems circuit wizard
Blue Sea Systems Circuit Wizard wire sizing calculator

We also found this helpful automotive wire sizing calculator from Wire Barn that shows you more detail on what gauges will or won’t work, as well as other pieces of information like voltage drop for each.

Here’s an example of choosing the correct wire size using our Acegoo 12V LED lights

acegoo RV Boat Recessed Ceiling Light 4 Pack Super Slim LED Panel Light DC 12V 3W Full Aluminum Downlights, Warm White (Silver)

We have a 12V electrical system, so we’ll use that as our system voltage.

System voltage = 12V

Per the tech specs on our Acegoo 12V recessed LED lights, they have a max current of 3W per light. To convert that to amperage, we divide by the system volume (3W / 12V = 0.25A).

Each light is wired individually to the switch, so we need wire that can handle 0.25A of current.

Max current = 0.25A

We planned on installing each light no more than 6-10 feet from the switch (we’ll assume 10 feet to be on the safe side). To get our total wire length, we’ll multiple 10 feet by 2 to account for both the positive and negative wire.

Wire length = 20 feet

Plugging all these numbers into the Circuit Wizard spits out a recommend wire thickness of 22 AWG. (We ended up using 18 AWG to be extra safe).

But that’s not all. We also need to wire the dimmer switch down to the fuse box. Since we have sic LED lights wired to one dimmer, we need to multiply the light current by 6 to get our max current:

Max current = 1.5A

The distance between the dimmer and fuze box is about 4 feet. Double that to get the total wire length:

Wire length = 8 feet

Plugging these numbers into the Circuit Wizard gives us a recommended wire gauge of 18 AWG. (We ended up using 14 AWG here, again to be safe, and so we could use the same wiring for our dimmer switches and outlets).

You’ll want to run this same calculation to get the proper wire sizes for all your components. In general, the wiring for things like lights, outlets, fan, fridge, and other DC components will be probably between 12 AWG and 18 AWG.

You’ll need much thicker wiring for your batteries, inverter, and ground cables. Again, you’ll want to calculate this yourself based on max current, length, and manufacturer recommendations. We used mostly 4 AWG battery cable for the batteries, and thicker 2 AWG cable for the inverter and ground connections.

Choosing the Correct Fuse Sizes

130PCS Standard Blade Car Fuse Assortment, SIM&NAT 1A 2A 3A 4A 5A 7.5A 10A 15A 20A 25A 30A 35A 40A Auto Medium Blade Fuses Kit - ATC/APR/ATO/ATS Automotive Fuse Assortment

Choosing the right fuse sizes for your circuits is very important for safety. A fuse is an intentional weak point in a circuit. If the current in the circuit ever gets dangerously high, the fuse will “blow,” breaking the circuit and saving you from some major electrical problems.

For your electrical loads (lights, outlets, fan, fridge, etc.), we recommend wiring everything into an automotive blade fuse box and picking up a set of blade fuses.

As a general rule, choose fuses that are above the max current of your circuit load, but below the amperage rating of your wiring.

Going back to our LED light example – the total max current of our light circuit is 1.5A. So, we fused this circuit with a 2A fuse. This is above the max current of our lights, but well below the amperage rating of the 14 AWG wiring we used.

For larger items like your batteries and inverter, you’ll want to use a different type of fuse. We used ANL fuse holders with the proper fuses for our batteries and inverter, and an inline MC4 fuse holder to fuse our solar panels.

Make sure to check the manuals for your solar charge controller, inverter, and batteries for manufacturer-recommended fuse sizes.

Note: Renogy’s premium solar kits include ANL fuses/holders, as well as an MC4 inline fuse holder. Then you’ll just need some larger ANL fuses for your inverter. And, if you use the coupon code GnomadHome at checkout, you’ll get 10% off your purchase!

Cutting and Crimping Wires

IRWIN VISE-GRIP Wire Stripping Tool / Wire Cutter, 8-Inch (2078309)

How do all these wires connect to each other and your components? With crimp connectors!

We used three kinds of crimp connectors for the thinner gauge wiring (22-10 AWG) in our van build: ring terminals, 1/4″ female quick disconnects, and butt splice connectors.

Pick up a basic electrician’s multi-tool and you’ll be crimping wires in no time. If you want to get a little more serious, you can pick up a ratcheting crimp tool for no-nonsense crimps that you know are strong.

Read more: Check out this article for a tutorial on crimping wires.

Crimping Battery Cable

TEMCo Hammer Lug Crimper Tool 5 Year Warranty

Crimping terminals onto battery cable (8 AWG and thicker) is a little more difficult, and requires specialized crimping tools.

The most basic type of crimper for battery cable is a hammer-style crimp tool (we used one of these for our build). This type of crimper is inexpensive, portable, and fairly easy to use, but it’s also easier to crimp improperly. There are also mechanical crimp tools and hydraulic crimp tools. Hydraulic crimp tools should give you best results, but they’re also bulky and expensive – which means it might not make sense if you’re only using it for one build.

If you don’t feel like messing with crimping your own battery cable, you can buy pre-made battery cables in various sizes with ring terminals already attached. The downside is that you’ll lose some flexibility in the placement of your electrical components, and the cost can add up quickly. Yet another option is to order custom-length cables.

Connecting the Dots: Step-by-Step Installation of Our Electrical System

Here’s the part where we go through how we installed all the pieces of our electrical system. Between cutting and crimping wires, arranging and organizing components, making mistakes and figuring things out as we went, this whole process took us a few days.

Mount and Wire the Solar Panels

installing solar panels

Important: DO NOT hook up your solar panels to the charge controller until the batteries are connected.

The first thing we did was mount our solar panels to our van’s roof and wire them together in parallel using a Signstek Y-branch wiring connector.

For parallel wiring, all the positive wires go together and all the negative wires go together.

We decided to wire our panels in parallel for a few reasons:

  • Parallel allows us to hook up the three panels on our roof and connect our fourth panel whenever we want.
  • With panels wired in series, if some shade gets on one of the panels the electrical output of the entire system will be affected. With panels wired in parallel, shade will only affect that one panel.

There are advantages and disadvantages to both parallel and series. Renogy has an awesome guide on the differences.

After we mounted our panels, we fed the wires inside the van and ran them through some conduit down to where we planned to put all of our electrical components.

Mount the Charge Controller

mounted charge controller_800x500

Next, we mounted our charge controller to the wall inside our van. Renogy recommends leaving a few inches of space all around for ventilation.

Wire Batteries Together in Parallel

wiring batteries together in parallel

If you have more than one 12V battery, wiring them in parallel is the way to go for a van system. To do this, connect the positive terminals together, then connect the negative terminals. We used 4 gauge battery cable for this.

Ground Batteries to Chassis

Next, we grounded our batteries to the vehicle chassis. We used 2 gauge wire for the ground connection. We screwed the ring terminal directly to the vehicle frame using 1-⅝” self-tapping screws and shake proof lock washers. The connection is rock solid.

grounding wires

How to Properly Wire Your Batteries


When you connect everything to your batteries, make sure you do it on opposite sides of your battery bank. What does that mean exactly?

Attach all of your positive wires to the positive post of one battery, and connect all of your negative wires to the negative post of the other battery. This allows your batteries to charge and discharge at the same rate and will help keep them healthy.

wires on opposite battery terminals

Check out this page for helpful diagrams showing how to wire together different sized battery banks in both parallel and series.

Wire Charge Controller to Batteries

For this step, we used the leftover 8 AWG wire that came with Renogy’s kit, crimping on ring terminals as needed. First, we ran 8 AWG wire from the positive battery terminal on the charge controller to one side of a heavy duty on/off switch. This will let us kill the connection to the battery if we ever need to.

Note: DO NOT disconnect the battery while the solar panels are hooked up to the charge controller. Whenever we need to cut off power to work on the system, we always make sure to disconnect our solar panels first. In fact, it may be a good idea to install a second cut off switch for the solar panels.

close up of battery switch mounted

Next, we ran more 8 AWG wire from the other side of the switch and connected it to one side of an inline fuse holder. The fuse should match the current rating of the charge controller (i.e. a 20A fuse for a 20A charge controller. We used a 30A fuse). Then, we ran 8 AWG wire from the other side of the fuse holder to the positive post on our battery.

anl fuse holder

Now that we had the positive connected, we ran a wire from the negative battery post and connected it to the negative battery terminal on the charge controller.

screwing batteries into charge controller

As soon as we made the connection, the charge controller turned on. Exciting!

Make Sure to Fuse Your Solar Panels

Renogy recommends adding a fuse in between your solar panels and your charge controller. The easiest way to do this is using Renogy’s inline MC4 fuse/holder, but any type of 40A inline fuse should also work.

Note: Renogy’s premium solar kits include all fuses that you need for wiring up your solar, including an inline MC4 fuse/holder and two ANL fuses/holders.

Use the coupon code GnomadHome at checkout for 10% off solar kits and more at Renogy.com!

Wire Solar Panels to Charge Controller

connecting solar panels to charge controller

This was simple enough. We inserted the positive wire from the solar panels into the positive solar terminal on the charge controller, then did the same with the negative wire. Now the solar panels were charging the batteries!

Wire the Load Terminals to the Charge Controller

charge controller wires

We ran 8 AWG wire from the positive load terminal on the charge controller to the positive terminal on our blade fuse block.

Next, we ran another 8 AWG wire from the negative load terminal on the charge controller and connected it to the negative terminal on our fuse block.,

To get your 8 AWG wire, you can use leftover wiring from the solar panels and crimp a ring terminal onto one end.

close up of grounding bus and fuse box

Installing the outlets was much simpler.

We first drilled holes and mounted them in place.

outlets in bench

Then we crimped quick disconnects onto both red and black wires and connected them to the back of the outlets.

fridge outlet from behind

We attached the other side of the positive wire to the blade fuse box using a quick disconnect, while the negative wire attached to the negative bus with a ring terminal.

The fan was the simplest.

Using butt connectors, we crimped additional wire onto the positive/negative wires coming to the fan. We then attached the positive wire to the fuse box using a quick disconnect, and attached the negative wire to the common bus bar using a ring terminal.

Wire Lights, Dimmer Switches, and Fan

Next, we connected our LED ceiling lights, vent fan, and outlets to the system. We used 18 AWG wire for the LED lights and 14 AWG wire for the outlets and fan.

Before we hung the ceiling we had attached wires to the lights and fan using twist connectors, and wrapped  it with electrical tape to prevent the connection from vibrating loose.

light hanging by wire

Then we labeled the wires and ran them through conduit down to the electrical area. So all we had to do now was connect everything together.

We hooked up the lights to dimmer switches.

We rigged up one dimmer switch in the front controlling a set of six lights, and another dimmer in the “bedroom” controlling two lights.

The awesome dimmer switch we used comes with three wires: a positive, a negative, and a ground.

front lights switch

Using a twist connector, we twisted together the positive light wires, the positive wire from the switch, and another wire that ran down to the blade fuse box.

We then twisted together the negative light wires and the negative switch wire.

We spliced the “ground” wire from the switch to a separate wire that connects to the negative bus bar.

Insert Blade Fuses into Fuse block

fuse box - horizontal

Adding fuses into the fuse block completes the circuit and makes sure your system is protected. When designing your system, you’ll want to base your fuse sizes on the max amperage of the circuit.

For example, if your fan circuit draws 3A, you’ll want to use a fuse as close to 3A as possible without going under it.

Hit the Switch Aaaaannnndd……

This is when things should turn on. But for us, nothing happened. We tried turning on the fan, turning on the lights – nothing.

It turned out that we had our charge controller set to cut off power to the load. If you get to this point and nothing turns on, check your charge controller settings!

Once we got the settings correct everything worked beautifully. The lights dimmed on and off, the fan turned on, the outlets charged our phones.

lights and fan on

Wiring the Inverter to the Battery

We mounted our inverter to the outside of the partition that separates the electrical enclosure from the storage area under the bench.

view from countertop with inverter
The inverter connects directly to the battery.

First, we ran wire from the positive battery post to a heavy duty on/off switch so that we can cut the power to the inverter if needed.

inverter switch and fuses

Next, we ran wire from the switch to an inline fuse holder with a 100A fuse. We used one of Renogy’s ANL fuse holders and replaced the 30A fuse it came with. From there, we connected a wire from the fuse holder to the positive terminal on the back of the inverter.

behind inverter

The negative wire goes directly from the negative battery post to the negative terminal on the back of the inverter.

Finally, we grounded the inverter to the van’s chassis using self-tapping screws and shake proof lock washers.

The inverter has regular 3-pronged outlets on the front. You can plug your AC devices directly into these outlets, or run an extension cord to a power strip or AC outlet elsewhere.

If you prefer to have hardwired outlets, you can cut off one end of an extension cord and wire it to a standard wall outlet (positive, negative, and ground), which you can then mount in an outlet box and attach anywhere you want. The intact end of the extension cord plugs into the inverter to draw power.

Pro Tip: Keep Things Organized!

Trust us, your life will be so much easier (and safer) if there isn’t a jumble of live wires spewed all over the floor of your van.

We concealed all of our electrical components in a compartment under the seat of our flip top bench.

van life electrical neat and tidy

We used ½” metal wire straps (wrapped in electrical tape) from Home Depot to organize the thick battery cables, and smaller wire clips and zip ties to hold down the smaller wires.

This keeps the wires out of the way, and also takes tension away from the electrical connections so they’re less likely to come loose while driving.

Awesome Resources for Further Reading

Conclusion

That’s just about everything we did for our electrical install. We tried to answer all the questions we had when we started out, and some questions that we had right up to the installation. If there’s something we didn’t cover, or you have a question, or we got something wrong, let us know in the comments!

We’re supremely pumped to have power in our van – it definitely makes those late night van build sessions a lot easier!

Stay tuned for more build updates as we go into building our awesome furniture. And don’t forget to follow us on Instagram @gnomad_home and on Facebook at Gnomad Home.

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  • Hey, Great post, super cool what you two have done! I have a question. I have a similar Van- 96 Starcraft conversion- and I cannot find the fuse box for the Conversion parts anywhere (TV, mood lights etc). The ones for the engine and general car workings are pretty easy to find so I am not sure if there is one as I have looked everywhere. Did you come across the original one on yours when you ripped all the wiring out? Thanks for reading great work!

    • Hi Blair, in our van the fusebox for all the conversion stuff was down under the steering wheel to the left of the driver’s feet (behind a plastic covering). Since your conversion was done by a different company, this may be different in your van. Hope that helps!

      ~John

  • Ho John, very helpful info here. At the beginning of the article you listed the battery isolator as an important component to have. Where does the isolator fit into the diagram? My guess would be between the batteries and the charge controller?
    My current set-up in the van I bought is an auxiliary battery onboard and a starter battery under to hood. They are both currently charged by either the alternator or by a battery charger when plugged in to shore power. We would like to add solar to the set-up to be able to spend more time off grid.
    Any tips you can give on how to integrate the solar would be great!

    Thanks, Bryant

    • Hi Bryant, the isolator actually goes in between the starter battery and the aux battery – i.e. starter battery positive terminal –> isolator –> aux battery positive terminal (with fuses in between). It sounds like you may have you batteries wired up in a similar fashion already. As far as incorporating solar, there’s nothing special you need to do – just hook your charge controller up to the aux battery and you’re good to go. Hope that helps!

      ~John

  • Hi there, fantastic post.

    My question:

    Do I need to place the fuse box between the charge controller and the battery system?

    You say you run 8 AWG positive wire from charge controller to the fuse box, I thought you hook the fuse box up from the battery?

    Also, from the fuse box you run your 12V wiring system out to your 12V appliances?

    • Hi Kyle, thanks for reaching out. With Renogy systems, the fuse block for all your 12V components is separately attached to the charge controller. The fuse block is not in between the CC and the battery, the CC has separate ports for hooking up your 12V fuse block. If you choose, you could attach the fuse block directly to the battery instead, but you would lose out on some of the metering functionality provided by the CC. And yes, you would attach all your 12V appliances to the 12V fuse block. I hope that helps!

      ~John

  • Hi John, very informative article! I read through it all and a handful of the comments. I’m not very knowledgeable on electricity and it’s a bit of a confusing subject for me. Would the Highest Budget option be best if I wanted to run a fridge, microwave, fan (possibly a roof AC) and maybe a space heater in the winter (if needed). Everything would be running at once, but at times I could see 2-3 things going at once depending on the weather. Also when the van is running is it possible to charge the battery bank, or is everything strictly on solar?

    • Hi Luke, the roof AC and the space heater will both draw significant power, and might be tough even with the high budget option we outline (especially in winter, when you will be getting less sun). The best way to tell is to do some calculations.

      First, list the components you want to run along with the number of hours per day they will be running.
      Then, find the wattage of each component and multiply by the number of hours (i.e. a 1200W microwave run for 6 minutes each day = 120Wh; a 2000W heater run for 1 hour = 2000Wh).
      Next, take the total watt-hours and divide by your system voltage (generally 12V) to get the amount of amp-hours (ah) of electricity you need to use. So, 4000Wh / 12V = 334ah. If you are using lithium, that 334ah represents how much battery capacity you need (I would oversize and go with 400ah of battery). If you are using AGM or lead acid batteries, multiple this by 2 (these batteries can only be drawn down to 50%), so about 800ah of battery.
      As far as how much solar you would need, a general rule of thumb is use one 100W panel for every 50ah of lithium, or every 100ah of AGM/lead acid – so in the example above, 800W of solar would be a safe bet.

      To answer your last question, you can charge your batteries while the van is running if you install a DC-DC charger.

      Hope that helps!

      ~John

  • How can I ground one 100Ah battery if I can’t reach my vehicle’s chassis? Is grounding the battery required?

    • Hi Sarah, if you can’t reach the chassis, you can can ground all of your components (battery, inverter, etc) to a common bus bar instead. If you can access a point on the chassis that would be preferable, but your system will still function if it’s grounded to a bus bar. Make sure to get a heavy duty bus bar rated for a high amperage. Hope that helps!

  • Hi guys, I have a question: how did you choose the 100amp fuse for the connection between your inverter and battery? I’m having trouble figuring out how to size the fuse for this part, and the inverter manual/company hasn’t been helpful here. I’ve tried researching online to no avail. My inverter size must be odd, because it isn’t included in any of the online charts. I’m so sorry if you’ve already answered this question; tried searching for the answer in your responses, but 319 comments is a LOT of comments ha! Im glad you can help so many people out here!

    • Hi Emma, so sorry for the delay. The fuse size we chose was based on the wire size that we used to connect the inverter to the battery. We used 2AWG wire, which is rated for about 100A, so that’s the fuse size we used. Your fuse size should be based on the size of your wiring, and your wire size should be based on the amperage that’s going through it.

      There’s a multi-step process to figure this out:

      1. Calculate the max amperage going through your wire. To get this, take the surge wattage of your inverter (the highest wattage that is might pull) and divide it by the voltage of your system (usually 12V in a van). So, if you have a 1000W inverter with a surge wattage of 2000W, then divide 2000W by 12V (2000 / 12 = 166.67 Amps).

      2. Figure out the wire size you should use that can handle that many amps. There are several 12V ampacity charts online, but Blue Sea Systems has both a chart and a calculator: https://www.bluesea.com/support/articles/Circuit_Protection/1437/Part_1%3A_Choosing_the_Correct_Wire_Size_for_a_DC_Circuit

      Looking at that chart, we want to find a wire size that can handle at least 166 Amps, which would be 2/0 (can handle up to 200 amps).

      3. For the fuse size, you want a fuse size between 166 Amps, (the max current of the inverter) and 200A (the max current rating o the wire), while being as close to 166 Amps as possible. This will probably be 175 Amps.

      Hope that helps, and best of luck!

  • Hello great info couldnt have done it without this site!!! I have a question about my rover mttp charge controller. I went with 2 125 vmax agm batteries and the the 20 a rover charge controller. There is no info that i can find how to set this controller for an agm battery. I currently have it set to gel setting. I thought about using the (use) setting and customizing the
    Float and boost voltage. But i dont know what to do about the equlization setting that cant be turned off only voltage adjusted. WHAT SETTING DO YOU USEFORAGM BATTERIES WITH ROVER CHARGE CONTROLLER??? please help:).

  • Hi there! We have a 400 w system (4 100s) and are curious about wiring in both series and parallel.. but i don’t see many people doing that.. is it not possible? or does it just not work very well? thanks!

    • Hi Alex, great question! I think it depends on your setup, but if you plan to mount 4x100W on your roof, then series-parallel is the way that I would wire it. You would essentially wire each set of two panels in series, then wire that together in parallel. This gives you the best of both worlds – the higher voltages of series wiring, plus the panel independence of parallel (i.e. if one panel is shaded, it doesn’t affect the performance of all four – just the one it’s in series with).

      Series parallel is not possible in some situations, which could be why you see less of it. For example, if you had only 3x100W panels, series-parallel would not be possible. In order to wire in series-parallel, the components in parallel need to be equal, meaning you need an even number of panels. You could series-parallel four panels, or six panels, but not three, for example. 4x100W is basically the minimum system size for series-parallel, and many vanlifers run smaller systems or an odd number of panels. We chose to wire ours in parallel for two reasons: we could only fit three of our four panels on the roof, and we wanted the ability to plug in our fourth panel when we were stationary. That basically required us to go with parallel. If we could have fit all four on our roof, we would have done series-parallel.

      Renogy has a helpful article on series vs parallel, complete with wiring diagrams for series, parallel, and series parallel: https://www.renogy.com/learn-series-and-parallel/

      Hope that helps! Best of luck with your build!

      ~John

  • Hi! Thanks so much for this guide, it’s been extremely helpful for me during my van conversion. I’m using the 125Ah VMAX battery that you recommend (with a 100W Renogy panel and a 20A Epever MPPT controller). Whenever the battery is charging I’m noticing a bubbling/fizzing sound coming from inside the battery. I tried a new battery but the same thing is happening.. can you tell me if you ever hear similar noises from yours? Is it normal? (The internet seems to have very conflicting opinions about whether AGM batteries should be making noise..it’s really hard to know what is true!)
    Thanks so much.

  • Hi! I bought the VMAX batteries (125Ah) that you recommend above, to use with a 100W Renogy panel and 20A MPPT charger controller. I have noticed that they make a bubbling/hissing sound as they are charging. Is this normal? Do your batteries do this as well?

    • Hi Jasmine, our batteries do not make noise when charging, and I don’t think they should be bubbling/hissing. I would contact VMAX customer support. Hope that helps!

      ~John

  • First of all, thanks a lot for this great blog that I have been using a lot recently . We are just camping warriors and I have decided on a battery isolator and an AGM deep cycle 100 Amp as our electrical needs are very limited (powering the fan mostly for now). I have read that these batteries should be used at less than 50% of their capacity, so how can I tell ? do I need a charge controller despite the fact that (for now) we don’t have solar panel ? Or can I use another device (I don’t know much about electricity) ? thanks a lot

    • Hi Nancy, I’m so glad our site has been helpful! You are correct that it’s generally not a good idea to deplete AGM or other lead acid batteries below 50%. The easiest way to tell would be check the voltage using a voltmeter/multimeter, or by installing a battery meter like this one.

      These devices will tell you your battery voltage, which is a fairly easy way to see where your batteries are. In DC systems, nominal voltage (12V in a 12V system) is approximately 50% charged. So, you can just keep an eye on the battery voltage and make sure it doesn’t dip below 12V. Going a little bit below is not the end of the world, but it will shorten the life of your battery if you do it regularly.

      There are some additional complexities to think about – for example, if you’re running something that draws a lot of power, that will cause your voltage to drop while it is running. But when you turn it off, the voltage should rise back up. The voltage to pay attention to in terms of your battery’s state of charge is the voltage you see when you’re not running heavy loads.

      I hope that helps clarify things a bit!

      ~John

  • Hi John,

    I’m curious, are the outlets you ran from your fuse box for AC appliances? If so, why did you decide to do that instead of running outlets from an inverter? I know you have a power strip coming from the inverter, but I’m curious as to why/ how it works to have outlets coming from DC power/ the fuse box. Seems like others have their outlets coming from their inverter so it’s AC power.

    Thanks for the article, it’s a great research and I’ve learned a lot from it.

    Sam

    • Hi Sam, the outlets you speak of are all 12V outlets. Our entire van runs off of 12V DC, including our lights, fan, and fridge. The 12V outlets are cigarette lighter style, and we plug in USB or USB-C charging units for charging phones, speakers, headlamps, lanterns, and anything else with a USB or USB-C connector. We originally included a mixture of 12V USB outlets as well, but these did not output enough amperage to keep up with today’s quick-charge technology, and also constantly emitted an annoying blue LED light. Having 12V cigarette lighter plugs allows us to switch out for newer technology as-needed.

      As for our inverter, we keep it off unless we are using it (we typically only use it for occasionally running a blender, coffee grinder, and charging our computers). Inverters draw a small amount of power even at idle, so if we keep it on all the time then it will be drawing power all the time. Also, inverters are not 100% efficient – most have about a 10% power loss. So, wiring our entire van for 120V run off the inverter would mean that we would be using 10% more electricity vs keeping all that we can 12V. Even with our relatively large system, we’ve definitely been in situations where we’ve tested the outside limits of our electrical capacity, so we’ll take efficiency gains wherever we can get them.

      I hope that clarifies things! Let me know if you have other questions!

      ~John

  • I can’t wrap my head around why the fuse between the battery and the inverter is so large. Even if the inverter is rated for it, wouldn’t I have to be doing something terribly wrong to draw 100 amps off the battery? That’s like 3 table saws, a toaster oven, and a washing machine xD. Or am I missing something between the conversion of DC to AC?
    Thank you so much for this valuable resource – it’s been great for planning out my solar.

    • Hi Cam, the fuse sizing is generally based on the wire gauge to prevent the wire from overheating. While it definitely may take a lot of devices to draw 100A continuously, I believe the thick wire gauges and corresponding fuses are more to accommodate surges. A blender, for example, is going to have a startup surge that briefly draws more power than it does when it’s just running. If you go with a fuse that’s too small, you may risk popping the fuse with startup surges. Hope that helps!

      ~John

  • This is all so intimidating! We are on a barebones budget and wondering if we absolutely need solar panels if we are going to have a vent fan. Thank you for any insight!

    • Hi Whitney, you definitely don’t need solar for a barebones electrical setup, but you do need to make sure you have enough battery capacity for the things that you’re running, as well as a means to charge up your batteries, such as a battery isolator. The typical vent fan draws between 1A (on low) and 3A (on high), per hour that it’s running, so it can be a fairly significant load if you’re keeping it on all the time.

      If your means of charging is a battery isolator, that means you’ll need to drive your van in order to charge up your batteries. If you’re planning on driving frequently, this can work out just fine. But you’ll need to make sure that you have enough battery to get you through the periods when you’re not driving, i.e. not charging.

      The big advantage of solar is that you can charge up while you’re stationary, but it definitely adds some cost and complexity to your electrical installation. However, it could also allow you to cut back a bit on batteries compared with just running off an isolator – depending on how frequently you drive.

      I hope that helps!

      ~John

  • Hey, great post! Do you think a normal Voltmeter is enough to monitor the charge of the batterie? Where would I wire it in? Directly to the batterie?
    Cheers
    Paul

    • Hi Paul, a normal voltmeter should work just fine, since the voltage is really all you need to keep an eye on. You would wire it directly to the batteries, or you can buy inexpensive battery meters on Amazon that include a shunt. Hope that helps!

  • Hey, quick question as I’m currently copying and pasting this set up into my DIY skoolie.
    When you ground the batteries to the chassis, do you ground each of them separately or does one connection do the job? Thanks in advance.

    • Hi Allyson, assuming your batteries are wired together one connection takes care of the grounding for both. Hope that helps!

      ~John

  • John, thanks for all of the info. Im looking to do the more budget option, without any solar. Ive been working on an astro van, and looking to do some camping, but not really the full van life experience. Im hoping to setup a secondary battery with an isolator to power the car stereo and basic original electronics, including lights and 12v outlets, in the vehicle when the engine is off, but Im getting mixed information about whether or not I can do this. I think what you and many other people are doing is creating an electrical system entirely separated from the vehicles original system, and using the isolator just to help charge the secondary battery. But in my case, when the isolator cuts the connection to the starter battery, can I still run the vehicles electronics? Thanks in advance for any advice or recommendations.

    • Hi Mike, thanks for reaching out! In order to do what you’re talking about, you would need to change the wiring for the stereo, lights, etc, so that they are being powered by your secondary battery instead of the main vehicle battery. One way to do this would be to reroute the wiring. There should be a fuse box somewhere (under the hood, under one of the seats, or down by the driver’s door are all places to look) where all of these components connect. If you figure out which fuses are for the stereo, lights, etc, you can then reroute those wires to your secondary system. Hope that helps!

      ~John

  • Hiya! Thanks so much for the awesome post, its been such a huge help. Question on the placement of your battery on/off switches. If your not supposed to have your panels hooked up to the charge controller without also being hooked up to the battery, why put an on/off switch between the battery and charge controller? Wouldn’t that possibly damage the system if you shut it off?

    • Hi Andy, great question. Yes, you would not want to shut off that switch without first disconnecting the solar panels. We did this in order to be able to shut of the load in case we had to work on the system. But we’ve since rearranged things so we no longer have this cutoff switch. We are working on a full update of this post and the wiring diagrams currently. Hope that helps!

      ~John

  • Hi, Thank you for the entire article and for making sense of wiring a solar system to a van. I am in the process of buying a van. I am looking at a Ram Promaster 2500. how many solar panels can I fit on the roof of that van? and do you wire the ceiling fan into the solar system or into the vans own electrical unit?

    • Hi Jamie, thanks for reaching out! That depends on the wheelbase you get (i.e. the length of your Promaster), but if you want to max out your solar you should be able to fit at least 6-8 panels (600W – 800W) on the roof. Keep in mind that you will also want space available to install a ceiling vent fan. You may be able to fit more up there depending on how you arrange them, but it’s generally a good exercise to size your system based on how much electricity you plan on using, since costs can quickly escalate with a bigger system. As far as wiring the fan, you will want to wire it into your separate auxiliary electrical system (which should include an auxiliary battery bank as well). If you wired it into the van’s electrical unit, you will end up draining your starter battery pretty quickly. Hope that helps!

      ~John

  • Hey guys! Firstly, wanted to say thanks for this whole site! It’s helped me a ton and I made sure to buy everything I needed from you links :). I was curious if you had any tips for installing the isolator? I just got one and my solar is basically the exact same you have but with 2 100-watt panels and one single battery. ( just traveling here and there, not living.) any suggestions?

    • Hi Trevor, thanks of reaching out, and thanks for the support :-)! We go over how we installed our isolator here:

      https://gnomadhome.com/vanlife-installing-battery-isolator/

      We need to update this post, so here are a few additional tips:
      –I highly recommend fusing at both ends (by the starting battery and by the aux battery)
      –Instead of just running the bare wire under your vehicle, run it through some wire sheathing first. This will help prevent abrasion on the wire and potentially cutting through the insulation, which will cause your fuses to blow.

      Hope that helps! Let me know if you have other questions!

      ~John

  • Hi! Awesome and informative post!! I have one question. Im not sure should I use 40A, 30A or smaller fuse between solar panel and CC. I have 285w 24V solar panel and 30A CC. My battery is 12v 220ah AGM. Thanks a lot!!

    • Hi Lii, your charge controller should have fusing guidelines, but in general you want to use a fuse that matches the amperage of your charge controller (i.e. 30A for a 30A charge controller). Hope that helps!

      ~John

  • Awesome guide guys! Any update on installing permanent AC wall outlets? I have pretty much the exact same electrical system as you guys but am currently trying to wire outlets and having some difficulties. I will keep researching but would love to hear if you’ve had any success since our systems are so similar. Thanks!

    • Hi Josh, thanks for the kind words! Installing permanent wall outlets involves wiring the outlets to your inverter. There are two ways you could do this:

      1. Purchase an inverter that has direct wiring outputs (meaning terminals to connect positive/negative/ground wires for directly wiring to an outlet). Your typical RV/campervan inverter generally only has typical 3-pronged outlets as the ouputs, and does not include direct wiring terminals. However, it is possible to find these if you go looking on Amazon, including from reputable companies like Samlex and AIMS.

      2. If your inverter only has 3-prong outlets for the output, you can use an extension cord. Plug one end into the inverter, and run the other end to your first outlet. To wire it to the outlet, cut and strip the end of the extension cord. Inside there will be three wires (green=ground, black=negative, white=positive), that you can then wire to the back of the outlet.

      Pro tip: Wire your AC outlets in series. Make your first AC outlet GFCI (the one directly connected to the inverter), then all your downstream outlets will automatically be GFCI protected as well.

      We’re working on updating this post for 2020, and we’ll make sure to add details and diagrams about wiring AC outlets. Hope this helps!

      ~John

  • Thanks for all the info, in ONE place! I’m just beginning to put together an electrical system in my 1997 Chevrolet Express 1500, and trying to figure out what in the devil I’ve gotten myself into was getting confusing and disheartening. Thanks, again!!!

      • It’s so much easier to refer to your page, and put it all together. I’ve gotten the isolator installed, the cable running underneath to the passenger side running board, then up through the grommet into the van with no need to drill into the floor. Waiting for a battery box to put the batteries into and then set up in front and under the backseat/bed. Not doing solar yet, but it’ll be a snap after all of this. Much thanks to all of the instructions and pictures/videos that y’all were kind enough to share!!!

  • I’m using a renogy 300w panel (and controller) with four lithium-iron phosphate batteries. I bought used from someone, and was only using a 80cu Dometic fridge, so I waited for the batteries to drain before installing the panel (I actually have 900W, but that seemed like overkill for what I needed, so I only put 300 on the van). It took about two weeks for the batteries to deplete, then I installed the panel. Perhaps it was a mistake to fully discharge the batteries, but now I feel like once I finally got the batteries charged again (with the solar installed), they depleted with only a few days of overcast weather. Any ideas why? I can’t imagine that a Dometic 80CU fridge pulls that much from the batteries. I feel like the system isn’t functioning optimally.

    Also, do you know of anyway to run the fridge directly from the solar in the day (since it’s AC/DC) and then to switch it to batteries at night?

    • Hi James, so sorry for the delay in responding to this! So do you have 400ah of batteries? It’s definitely hard to imagine a Dometic fridge depleting that large of a LiFePO battery bank that quickly, but our system definitely drains down in a few days of overcast weather. Are you running other loads like a vent fan, etc? I hope things are working better for you now!

      ~John

    • Hi Syd, our entire electrical system cost us right about $2,000. This included solar, batteries, inverter, isolator, and all wiring, fuses, and other components. This same setup would probably cost slightly less today, since some of the components are a bit cheaper than they were three years ago. You can see a further breakdown of our build costs here: https://gnomadhome.com/our-rig/

      Hope that helps!

      ~John

  • Thanks for sharing. I found a lot of interesting information here. A really good post, very thankful and hopeful that you will write many more posts like this one.

  • Hi there,

    So, I bought the exact same solar and battery setup as you guys and I am curious to know what you have set for Charged Voltage on your Battery Monitor and/or Charge Controller. For example, say you are entering your van about an hour after the sun has set, what voltage would your battery monitor read at that time? Please let me know. Thank you so much for your time and effort with putting the website and how-to’s together, I know the vanlife community greatly appreciates it.

    Best,

    Andrew

    • Hi Andrew, thanks for commenting and thanks so much for the kind words! When our batteries are fully charged and no longer taking in energy from the sun, I would expect the voltage to be in the neighborhood of 12.8-12.9. Nominal voltage (i.e. 12.0 in a 12V system) is about 50% charge, and you will want to stay above that (assuming you have lead acid or AGM batteries). Going below 12.0 too frequently will effect the longevity of your batteries. Hope that helps!

      ~John

  • Greetings, I can’t thank you enough for wealth of info and experience from your guides and articles. One question about sizing… I believe that you mentioned a good rule is to match the solar to the batt capacity. In your system you have 400 w of solar power and (I believe two 155ah batteries) for 310ah. So you have more solar than your batt capacity – ok makes sense to me. But what about budget and future builds… If I can afford 200 w of solar power (two panels) I was thinking of getting the two 155ah batteries for the future. However if I only have 200w of solar and 310ah capacity it will never fully charge the battery… am I at risk of damaging / loosing batt life? Don’t know if I have to go with the 100ah batt vrs the 155ah. Thank you kindly.
    -Brian

    • Hi Brian, thanks for reaching out! We actually only have 300W of solar permanently mounted on our van. The other 100W panel we keep stored in the trunk for additional as-needed capacity. With 300W of solar and 310ah of batteries, we are usually able to fully charge each day, but if we have several days of overcast weather or are spending time in the woods (where there isn’t always full sun), we can run into charging issues, even with our fourth panel, so I would say that 200W of solar alone would have a tough time keeping up if you’re using a lot of electricity.

      However, adding a battery isolator into the equation will help out a lot. This will allow you to charge your batteries from your vehicle’s alternator while the engine is running. You may have to plan on either driving or running your engine for a bit at least every couple of days to keep your batteries topped off, but an isolator would help you keep up with your batteries until you can invest in more solar. Many vanlifers start off with just a battery and an isolator, and add solar down the road. Hope that helps!

      ~John

  • Hi John! Thank you so much for creating this great resource. Your website has kept us sane on our van build journey the last few months!

    I have a couple of questions for you on determining wire sizes. I am a novice when it comes to anything electrical related and am having a hard time wrapping my head around some of it. We have purchased the same lights that you have in your van, but we plan on wiring them in series. When determining the wire length for the calculation, should I be using the length from the light switch to the end of the fourth light (x2) or just the distance from the switch to the first light and then the distance between each successive light?

    I also seem to be completely missing how to determine the load current on the wires connecting the light switch to the fuse box? And the load current on the wire going from the battery to the fuse box (our charge controller does not have connections to the load/fuse box, only to the solar panels and the battery), we are using the total amount of amps on everything we have plugged into our fuse box (vent fan, lights, etc), correct?

    • Hi Lindsay, so glad our resources have been helpful! For calculating the wire length, you will want to use the total length of the wiring in the circuit – so, from the light switch to the lights (and in between the lights) and back.

      For the load current, you will want to calculate the max amperage of all the lights in the circuit combined. For example, those LED lights are 3W each on full blast. 3W x 4 lights = 12W total. To calculate the amperage, divide the wattage by the voltage of your system. Assuming you’re running a 12V system, 12W / 12V = 1A. So, you’ll want to use a fuse that’s as close to 1A as possible while still being above it (the smallest we could find was a 2A fuse), and use wiring that can handle at least as much current as your fuse is rated for.

      The easiest way to calculate the load current from the battery to the fuse box is to add up the amperage of all your fuses (so yes, the total amps for everything you have plugged in). It’s not a bad idea to size up a bit so that you have some wiggle room to add more circuits as needed.

      Hope that helps, and best of luck with your build!

      ~John

  • Hey, I couldn’t find on your blog what determines wire size between charge controller and fuse board. Would it be the total load on fuse board or the charge controller size.

    • Hi Will, there are a few factors in play here:

      1. The total load on the fuse block. You always want to make sure that your wiring can handle any potential loads that might go through it.
      2. The load capacity of the charge controller. For example, Renogy charge controllers can only handle 20A of continuous load (even the 40A ones – the amperage rating refers to charging amperage, not load amperage). Even if you have more than 20A on your fuse block, you’re probably not going to run everything at once, so this may not be an issue (you could also wire loads directly to the battery).
      3. The size of the wire connectors on the charge controller. For example, the slot to insert the wiring into your charge controller may only be big enough 10 AWG wire.

      Generally speaking, 10 AWG or 8 AWG should be adequate for most campervan applications. If you have a Renogy CC that can only output 20A load, then 10 AWG will work perfectly. This handy chart shows max loads for different wire gauges. Hope that helps!

      ~John

    • Hi Ervin, thanks for reaching out! We actually just have a regular ol’ inverter without any charging ability. But, I certainly would recommend an inverter/charger over a converter/charger in most cases. All the converter/charger does is convert the 120V AC electricity from plugging in at a campground to 12V DC so that it can charge the batteries. With this setup, you can only use 120V AC while you’re plugged into shore power (unless you also get a separate inverter) This could be a fine option if you’re always going to be plugged in.

      An inverter/charger, on the other hand charges your batteries and allows you to use 120V AC when you’re boondocking in the middle of nowhere, since it also has an inverter built in. This is going to be the best option if you want to camp far away from electrical hookups but still need 120V AC power.

      Hope that helps!

      ~John

  • Awesome work guys! Made things so much easier for me.. I am currently planning my own first van build

    Thank you so much !

    😀

  • This is the best article on the subject that I have seen! Stressed newbie here. Question: how do you use a larger wire when your charge controller only accepts a 8 AWG? Like if you want to use a larger wire out to the solar panels?

  • Hi – How are you? Thanks for all the great info – I have a question – your simple wire diagram shows a shut off switch between the solar panel charge controller and the house batteries. This would allow you to disconnect the batteries while the charge controller is still connected to the panels. This is a big No No. Shouldn’t there be a switch between the panels and charge controller instead or in additon? Thanks. Steve

    • Hi Steve, disconnecting the batteries while the solar panels are still attached is absolutely a big no-no, as we mention in the post. We usually just disconnect the positive wire from the solar panels to the charge controller first, but adding an additional cut off switch is a good idea. We are planning on updating this diagram in the future to reduce any confusion on this point. Thanks for the input!

      ~John

  • Thanks for the useful guide.
    Did you ground the inverter and batteries at different locations or at the same point on the chassis?
    Also where do you run the grounding cable from for the inverter/battery, the negative terminal?
    Kind regards,
    Jake

    • Hi Jake, so glad our guide was helpful! We did not ground them to the same point, but the grounding screws are attached very close to each other. In general, you want the ground wire to be as short as possible, and the inverter to be as close to the batteries as possible, so grounding them in the same area is a good idea. The grounding wire for the battery is attached to the negative terminal. The inverter has its own separate grounding post. Hope that helps!

      ~John

      • Hi John,
        Thanks for the reply, yes I can see the separate grounding post on the inverter.
        The grounding cable that came with my inverter is very thin (~14 awg). I have a very thick cable I can use instead, however I don’t understand why the company provided such a thin cable, and the grounding post itself is smaller than my thick cable. Would you recommend I use the thick wire or the thin one that the manufacturer provided?
        I’m a bit concerned that grounding at the same point might interfere with the inverter or battery, what do you think?
        Kind regards,
        Jake

  • I really CANNOT THANK YOU ENOUGH for this post. I put in a 200w solar system with two 125ah vmax batteries and I’m so so so thrilled with it so far. This post, and all the detail you went into (which I know was probably SO MUCH WORK) was my bible for getting the system running. Literally every detail, like which wire you hooked up to which terminal and when, was so helpful. The only thing I wanted to add is that this charge controller can really only handle small loads, like my Fantastic Fan and some LED lights. I had to pull my fridge off the fuse box and wire it directly to the batteries. Although the charge controller says it’s 40ah, if you dig into the details it can only handle 20ah, and my fridge would throw a “load short” error since it starts up at 17ah when you first get it going. Other than that, wowowow this post is EVERYTHING and you guys are ANGELS.

    • Hi Iris, we are so happy that our guide was helpful! Wiring the electrical/solar was super intimidating when we did our build, and there just wasn’t a lot of cohesive information out there at the time. We’re always stoked to hear that our work made someone’s build a little easier!

      Thanks for adding that about the charge controller, that is definitely a good point to mention. All of the Renogy charge controllers can only handle a 20A max load (the 40A is charging current, not load), and it is certainly important to make sure you’re not running more than 20A through it at once if you don’t want to run into issues. 20A has been more than enough for our usage – our Fantastic Vent (and most vent fans) draw a max of about 3A on high, a set of LED lights are less than 0.5A on full blast, and our ARB fridge maxes out at 7A on startup (we have it on a 7.5A fuse). Since your fridge draws so much more at startup, wiring it directly to the battery was definitely a good idea.

      BTW, we love your Insta-handle! We consider ourselves to be expert portmantologists (although we refer to them as “werges” – word merges – around here, haha). Best of luck on the road!

      ~John

  • Hi, I’m working up a very detailed electrical diagram for my van conversion. all going well until I realised that several of the charge controllers I am looking at seemed to have very limited “load” output limits: 5 amps listed on one and 5 volts on another, perhaps I’m looking at the wrong value in the specification. have I just been sourcing rubbish charge controllers? Or is my expectation of a total circuit amperage too high?
    circuit 1: 15.5amps (2 lights and a lighter socket)
    circuit 2: 20.1amps (2 lights and a lighter socket and dual USB combo outlet)
    circuit 3: 19amps (fan, lighter socket and light)
    circuit 4: 15amps (lighter socket (for fridge)
    total is 70amps, hopefully at 12 volts since its a 12 volt system!

    Also, echoing those below, a wonderful resource, you gave me the courage to give it a go designing my own electric system. So thankyou.

    Best wishes,

    Tasha

    • Hi Tasha, so glad our resource has been helpful! What brand/where are you finding these charge controllers? I just looked at the specs for the Renogy Rover controllers and both models (20A and 40A) are rated for 20A of load current, which has worked fine for us with 12V LED lights, multiple lighter/USB outlets, fridge, and fan. 5A is far too low for a usable output – could you be looking at the wrong spec?

      Also, at first glance your circuit amperages seem a little high to me (but I don’t know what components you’re using). LED lights use barely any power (the lights we use/recommend draw 0.25A combined on full power), so we have both of our light circuits on 2A fuses (the smallest we could find). Our fan circuit is on a 5A fuse. Our USB/lighter outlet circuits are on 7.5A fuses. Generally, you want to figure out the max rated power draw of each item, and pick a fuse that’s higher but as close to to that amperage as possible. As far as drawing more than the charge controller is rated for (i.e. 20A for a Renogy unit) that should only be an issue if you’re running all your circuits to max capacity at once, which is very unlikely unless you have a short (which proper fuses should prevent).

      I also highly recommend separating your circuits as much as possible (i.e. separate circuits for each outlet, another one for lights, another one for fan, etc). That way it will be much easier to fix things if you blow a fuse or have a short.

      Hope that helps, and best of luck with your build!

      ~John

  • Hey, love your stuff! We are looking up our electrical now…when we are looking at input and output on our switches. How do you know where the input is coming from and where the the output goes? I’m trying to find a place where it says how to tell and can’t find it anywhere!! Thanks for the inspiration!

    • Hi Jillie, I’m not sure what you mean – can you clarify what type of switches you are looking at?

  • Hi, when you refer to ‘outlets’ what is it that you mean? Initially I thought you meant plug sockets but those require the inverter and you discuss those later and use extension cords straight from your inverter for this.

    Thanks for any clarification.

    • Hi Tom, we’re referring to 12V outlets, either cigarette lighter sockets or USB outlets. There are links to the exact outlets that we used towards the top of the post. Hope that helps!

      ~John

  • Hey there, your work in all of this has been very helpful. First question is that you say DO NOT disconnect the batteries while the solar panels are hooked up to the charge controller. Does that mean that is you flip the disconnect switch from the batteries to the charge controller that you should disconnect the panels? Second question, did you mount your charge controller hidden inside of a bench or out in the open in order to monitor the system whenever you want? if it is out in the open how often do you look at the charge controller display?

    thanks for your help.

    • Hi Zak, yes, if you disconnect the batteries the solar panels should be disconnected first (unless it’s nighttime). I’m sure you could add a disconnect switch for the solar panels to make this easier. Our charge controller is mounted in the open, as is the display. We look at the display at least once a day to monitor the battery voltage. But, if you have a remote display you could easily mount the charge controller in a hidden area and just have the display somewhere visible. Hope that helps!

      ~John

  • Thank you so much for all your amazing resources! This may be a silly sounding question to someone with more knowledge than me, but… You mention the possibility of adding on more to your “midrange” setup. So does that mean two 125 ah batteries could take the input from 3 100 watt panels?

    • Hi Natasha, thanks for reaching out! Two 125ah batteries can definitely take the input from 3 100w panels. Where you could be limited on input is with the charge controller. Per Renogy specs, a 20A charge controller can only take 260W of solar input (at 12V), whereas a 30A cc can take 400W of solar input and a 40A cc can take 520W. Hope that answers your question!

      ~John

  • Hi, I’m not sure if I overlooked it or not, but did you explain how to hook up the battery isolator? Thanks for all the details!

  • Hi, you could save a little power by getting a DC charger for your laptop. The laptop probably uses ~20V DC and by using the inverter you switch from 12V DC to 120V AC then the laptop’s charger turns that back into DC, with losses at each step.

    What a thorough guide!

  • Hi there,
    I bought the same batteries as you guys with a Renogy Rover 40A MPPT Charge Controller and I am wondering what parameters you set for your system. Please enlighten me. Thank you so much for your time, you guys are a true inspiration to my girlfriend and me.

    Best,

    Andrew

  • Awesome post, the Diagram is very helpful and makes this SO MUCH easier to digest. Newbie Question: Do you need to Ground the wires on the Blade fuse box on the Load side? I’m Planning on connecting wall outlets to the van (The kind you’d see in a house) and the wires used for those typically include a ground Wire. Any insight on this would be amazing! Thanks.

    • Hi there, thanks for reaching out! The blade fuse box can only accommodate 12V DC electrical (lighting, fridge, fan, USB outlets, other things that run off a cigarette lighter plug). To install regular 120V wall outlets, you will need an inverter. Inverters connect directly to your battery, and they convert 12V DC to 120V AC. Some inverters like this one allow you to attach wiring for outlets directly to them, but many simply have 3-prong outlets on the front. In our van, we plugged a couple of extension cords into our inverter and mounted the 3-outlet power strip ends in convenient places. We wrote a detailed post on inverters here that may help further:

      https://gnomadhome.com/best-12v-power-inverters-vanlife/

      Hope that helps!

      ~John

      • Thank you for Clearing that up! Follow up question, most inverters only have 2 outlets. Can I attach a multi-outlet block to both and run them to let’s say… 4 wall outlets?

      • Hi John,
        Thanks for your response, I’ve actually already read that other article as well 🙂

        I think my confusion lies in that I’ve never seen a complete circuit diagram that includes how the isolator AND the solar/charge controller interface with the battery bank simultaneously. So the main question I’d like to clear up is, in the diagram above, where does the isolator connect? Does it just connect to the positive battery terminal along with the wire coming to the positive battery terminal from the charge controller?

        • Thanks for the feedback! We’re updating both of these articles over the next few weeks and we’ll be sure to add diagrams showing how the isolator connects.

          You are correct, you would just attach a long cable directly to the positive battery terminal, right along with your charge controller. The other end of this wire runs into the engine bay and connects to the battery isolator. The battery isolator also connects to the positive terminal on your starting battery, and to chassis ground. Make sure to add fuses (100A or 150A) before each battery connection.

          I hope that helps!

          ~John

          • Thanks for the clarification!
            I’m approaching the electrical instal in the coming week and that was my biggest outstanding question. Appreciate the help!
            – Hayden

  • Thank you so much for all the great info. One quick question, my system is a little different than yours…no solar but will have shore. I know you connected your inverter straight to your battery. Do you see anything wrong with having the fuse box,wirtcho battery isolator, and inverter positive wires all connected to a busbar that then connects to the house battery (with a fuse).

    Similarly, having the negative wires for all those components running to a negative busbar that is grounded to a chassis?

    Thanks again,
    Ryan

    • Hi Ryan, one potential issue I see with that is that you would need a very thick gauge cable going from the busbar to the battery to handle all that potential amperage (same on the negative side). I would also make sure to fuse each device individually (i.e. add a fuse between the inverter and the busbar, etc.), and perhaps think about fusing the cable between the busbar and battery as well. Hope that helps!

      ~John

  • Thanks so much for the detailed info. Sorry if this has been answered before, but it seems like you’ve covered everything except the process of actually connecting to the car battery or alternator. Would you mind briefly explaining or linking how you went about that?
    Thank you,
    Ryan

  • John,
    By far the best van build site I’ve come across. I currently have a small travel trailer and am planning on doing a van conversion as soon as the snow melts. I do have a couple of questions: why do you size fuses just above the amperage of the device you are trying to protect but under the amperage of the wire? If a device is rated for 30 amps and your fuse is 35 amps could that be a problem? Also is it necessary to place fuse between solar panels and charge controller? Also how difficult is it to wire in a plug for shore power?

    Thanks for this site and all your help!

    Brian

    • Hi Brian, thanks for reaching out and for the kind words on our site! You want the fuse to be above the amperage rating of the device to prevent the fuse from popping in normal operation. For example, let’s say you have a fridge that says it can draw up to 7A (just an example, not specific to anything). That’s the maximum amount of current you can expect this appliance to draw, so you wouldn’t want to fuse under that in case it does draw 7A at some point. So, you would select a fuse that’s at or above 7A but as close you can get – say, 7.5A. Similarly, you want the wiring you use to be able to handle the maximum amount of current that might go through it, so you want to select a wire gauge that can handle at least 7.5A. Then, the fridge can operate normally, but if something goes wrong the fuse will pop before anything gets dangerously overloaded. Many of the bigger appliances like fridges and vent fans also have built in fuses as additional safety features.

      It’s definitely a good idea to add a fuse on the positive wire between your solar panels and your charge controller. Renogy recommends about 10A per 100W of solar for their kits. We have 400W of solar (300 on the roof, 100 in a portable panel that we plug in as-needed) so we added a 40A inline fuse. There are a few different kinds of inline fuse holders that will work (ATO/ATC fuses, AGU fuses, or ANL fuses), but make sure to get one that can accommodate the wire gauge that you’re using.

      To wire for shore power, you would need to incorporate some sort of battery charger unit into your system. If you already have your system built out, you can add a dedicated battery charging unit like this one. If you haven’t built out your components yet, you can get an inverter/charger combo unit. These units also typically have a built in transfer switch, which means that when you are plugged into shore power your 120V AC will pull from shore power directly instead of your inverter/battery. We go over different inverter/charger options in our inverters post. To actually plug in, you would need to install a shore power inlet like this one (make sure to match the amperage of your charger to the amperage of your inlet, because they can be entirely different plugs), and run a power cable between the inlet and your charger. Or, you could always string an extension cord through the window, but an inlet is much nicer :-).

      Hope that helps! Let me know if you have any other questions, and best of luck on your build!

      ~John

  • Hello,
    I am new to Van life and I am currently working on my van build and the thought of putting or wiring a solar system is completely intimidating. I plan on getting the Yeti (because I don’t mind forking extra out if I can sleep safely at night or day lol). However, I will be in the desert 90% of the time and it can get up to 120 degrees (Fahrenheit) and I will need to set up a air conditioning system. What should I add to make sure I have enough power? any recommendations for a good A/C? As you know batteries don’t last long out here but we have plenty of sun.

    • Hi Erica, congrats on your new vanlife journey! The Yetis are pretty good options that should allow you to run the basics. The Yeti 1250 also lets you daisy chain additional batteries to it if you need more capacity. But, running an AC unit will be a challenge with any kind of battery-based setup, since ACs draw so much power.

      You can do a lot to keep yourself cool with reflective window coverings, an awning for shade, and a roof vent fan. You can also look into something called a swamp cooler, which pumps out cool air and uses much less electricity than an AC unit. If you still feel like you must have an AC, I would recommend staying somewhere you can plug in or getting a generator. Hope that helps!

      ~John

  • Hey guys! Love the post!!! I’m putting in the same renogy system in my van and I had a question – did you use the grounding points on the aluminum frame of each panel? I couldn’t find anything on line about it expect renogy says the panels need to be grounded. In the context though it seemed more for permanent home panels and not for vehicles.

    • Hi Mick, we did not use the grounding points on the panel frames. I agree that this is likely more for fixed installations, as van setups are typically floating systems. I’m not aware of anyone who has grounded their panel frames to their vehicles. Hope that helps!

      ~John

      • Hi john! Thanks for the quick reply! I imagine the metal to metal contact from the bracket-screws-chassis combo counts as well in this case. Either way I appreciate it! And the info you’ve given makes me feel a lot better about the whole situation!

        Thank again! Mick

  • Very useful stuff ! I am wondering why you haven’t used 2 core cables directly (the ones with negative and positive cores together), it seems to me that it would reduce the complexity of the system when it comes to reaching the appliances (of course positive and negative would need to split to get to fuse box / bus bar 🙂 )

    • Hi Giacomo, thanks for reading! We did use 2 core wiring for our lights (we used 18 AWG two core speaker wire). I agree that this would simplify things, but I didn’t see any two core when we were shopping for the rest of our wiring. Thanks for the suggestion!

      ~John

  • I’m new to this stuff and your site has been so helpful getting me up to speed. Thanks!

    I’m trying to figure out if the inverter has some sort of built in battery controller so that the batteries don’t get depleted beyond 50%. I’m planning to use the Renogy 1000w inverter/charger so I can use shore power but I don’t want to deplete the batteries if they aren’t getting charged by solar. Thanks!

    • Hi Tyler, thanks for writing and glad the site has been helpful! The manual for the Renogy inverter/charger states that it has a low battery disconnect feature to prevent your batteries from being depleted. It looks like you may have to set it up, though – I would check out that manual and contact Renogy if you run into any issues. Hope that helps!

      ~John

  • Hi there,

    What would running your electric system strictly on DC look like? I’m confused as to how things would connect to the battery?

    • Hi Jacob, our electrical system pretty much is strictly DC. The wiring diagram on this post details how everything connects. With the Renogy solar kit that we used, everything routs through the charge controller: the batteries (+ and -) connect to ports on the charge controller, and there are also +/- ports on the CC for connecting your fuse box/negative buss. If you are wiring a system without solar, you can also wire your fuse box/negative buss directly to the batteries. We do have an inverter as well for 120V AC power, and that just connects directly to the battery. Hope that helps! Let me know if I can clarify any further!

      ~John

  • Hi John, the Renogy kit comes with 10Awg cable and not 8awg. Is this difference worth buying 8awg cable to make the connections where you said you used 8awg? I bought the same kit as you.

    Thanks

    • Hi Ben, thanks for catching that, I’ll update the article to reflect this. 10 AWG wiring is perfectly fine to use, but make sure it’s fused properly at 30A. 30A is perfectly adequate for the current running to/from a battery in most setups. Hope that helps!

      ~John

    • Hi Joe! To answer that question we need to figure out what amperage your light is drawing. Your light should tell you somewhere how much it draws (usually in watts). For example, the lights we have in our van draw 1.5W per light. To convert that to amps, divide the wattage by the system voltage (12 for a 12V system). 1.5W / 12V = 0.125A (we have six lights on one circuit, which equals 0.75A – LED lights draw very little power). Then, go with the smallest fuse you can find that is higher than the amp draw of your lights. We could not easily find any blade fuses smaller than 1.5A, so that’s what we used with our light circuits. Hope that helps!

      ~John

  • Hello there! Thank you so much for sharing these amazing resources! We are trying to build a van for weekend adventures and aren’t quite sure whether the barebones suggestion will cover our needs. We are getting the keyline isolator and the 125ah battery. We do not plan on using any 3-pronged devices so don’t want the inverter. We would like to run the ARB fridge, maxxfan 5100, charge phones, and run the puck lights you suggested. Is the battery sufficient for this consumption?

    • Hi Lydia, thanks for reading! The barebones suggestion is really more intended for basic usage like charging phones/computers and running a few LED lights. Adding a fridge and a vent fan, I wouldn’t expect the battery to last all weekend without solar or running the engine for awhile to recharge. Since you never want to fully drain your battery, the usable capacity of a 125 Ah battery is only about 63 Ah (this is 50% discharge. You can drain AGM batteries down to 20% – so 100 Ah usable capacity – but you will need to replace it far sooner than if you keep the discharge below 50%). The ARB fridge alone will draw about 1 amp per hour on average, so for a two-day trip that equates to 48 amps. That doesn’t leave much left over to run lights, a fan, and charge phones. Lights and phones won’t draw very much, but if you plan on running your fan for a significant stretch of time it can easily kill your battery if you’re not careful (vent fans typically draw anywhere from 0.5 amps to 4+ amps, depending on the setting). If you’re driving throughout the weekend you may be fine. But staying stationary, you may want to think about a bigger battery or adding solar, or make sure to run the engine for a little while on Saturday morning to charge it up. Hope that helps!

      ~John

  • THAnks for the great post
    I’m doing the lights and I have the wires from the dimmer swith going to the blue sea systems for which I don’t need a separate bus bar. Where would the ground wire from the dimmer switch go?

    • Hi Joe, we’ll have a diagram up soon showing exactly how to wire the dimmer switch. The Blue Sea Systems fuse box includes a negative bus bar, so you do have one even though it’s not a separate unit. The “ground” wire from the dimmer connects to the negative bus. The + wire from the dimmer connects to the + wire from the lights and the + wire from the fuse box. The – wire from the dimmer just connects to the negative wire from the lights. Hope that helps!

      ~John

    • Hi Harry, thanks for reading! The Renogy system (and many other charge controllers) are designed to run the load through the controller. The advantage to doing this is additional control over the load, and also data output about load usage. We can turn the load off or on directly through our charge controller, and we can also set timers for the load. Granted we hardly ever use these features, but they are there. The display monitor that we have connected to our charge controller also shows us information on load usage (the newer Renogy CCs have a display built in). That said, wiring straight to the battery works perfectly fine as well – but if your CC has ports for connecting the load there’s no reason not to, and you gain additional control and monitoring features. Hope that helps!

      ~John

  • Thanks so much for this article! It really is great.

    I want to add an induction stove top which will plug into my inverter.

    Its max power is 1800W, but I don’t think I’m going to use higher than 1000W.

    Going from 12VDC to 120VAC, this would mean 150A from the batteries to the inverter.

    Should I size the cables for surge peak power, or is this something I should protect by using a fuse?

    Thanks, love your blog.

    Ben

    • Hi Ben, no matter what you will want to protect everything with proper fusing just for safety. Your fuses should always match your wiring to prevent it from being overloaded. If you think you’ll only use a certain wattage, then sizing the wiring a fuses for that lower amperage will work – but if you do use more you might pop the fuse. We did this with our inverter – we didn’t want to buy the recommended 00 cable (and 150A fuse), so we used 2 AWG instead with a 100A fuse. As far as what is best for you, it depends on how you think you’ll use your stove. Hope that helps!

      ~John

      • Thanks John, I feel like it helped!

        Another couple of questions.
        I purchased the same Renogy solar kit as you, but seem to have received a newer model of controller. I’ve got a small, black Rover 40A MPPT controller with blue buttons.

        Anyway,

        You have a (maximum) 140A line into your battery from your super cool smart isolator.
        You have another line into the battery from the controller whose input is fuse-maxed at 30A.
        Finally, your batteries each have a maximum charge input of 35A. (do parallel batteries mean this max charge rate is doubled to 70?)

        My questions have to do with input charge control and management.
        1. a) Does the controller know the amperage input from the isolator?
        1. b) AKA does the controller know the total amount of amperage going into the battery from all sources?
        1. c) Does it adapt its charging to the battery based on what is coming in from the isolator?
        2. How do you protect from combined overcurrent into the battery from multiple sources to the positive terminal?

  • As everybody else has said, thank you so much for the well-written and clear guide!

    Just curious why you use a negative (common / vehicle) ground for the inverter and the battery instead of a bus bar? I assume you can’t use the same bus bar as for the ‘load’ circuit, but I was wondering if it would be possible to use another bus bar for the battery and inverter. Asking because I’m not sure I’ll have easy access to the vehicle chassis from my electrical setup.

    Thanks

    • It turns out that my solar charge controller (Victron 100/30 SmartSolar) doesn’t have a Load output, which means I’ll have to connect my battery directly to my appliance fuse box. It appears that in this case, since the batteries will be connected directly to the solar charge controller as well as the fuse box, that they will all (including the solar panel) have to share a common grounding. Is that right?

      • Hi there, thanks for reading and sorry for the delayed reply! We’ve been spending a lot of time off grid this fall, and we’ve admittedly neglected our comments. Sorry about that! Within the context of a van electrical system, all of your components that require grounding should be grounded to the vehicle frame/chassis, which is the common ground. You shouldn’t need to separately ground your 12V fuse box / negative bus – just wire those directly to the battery positive/negative terminals. Hope that helps!

        ~John

        • Hey John, no problem at all and good on you for getting off grid! =) Thank you again for the very helpful guide.

          A lot has happened since my post and I’m actually mostly done with my setup. I grounded the battery and all my components to a negative bus bar, any particular reason that’s not a good idea? Seems to be working fairly well and the bus bar has the amperage capacity for all my components.

          • If you’re just charging via solar, I’m not sure if there is a vital reason not to use a bus bar with enough amperage capacity, since the vehicle frame is essentially a big bus bar. But, if you decide to install a battery isolator to charge from your alternator, you will want to ground to the chassis so that all your systems share a common ground.

            ~John

            • Ah good point, we don’t have an isolator / alternator. If we did I see how we would need to ground to the chassis. Thanks for the help!

    • Hi there, glad you found our guide helpful! I’ll do my best to answer your questions. In our case we 100% needed chassis ground since we charge from our vehicle alternator using a battery isolator. Because of this, our aux battery needs a common ground with the starter battery / isolator, which is the chassis. Based on my understanding it is definitely possible to use a common bus bar as the return path instead of a chassis ground – so long as you’re not also charging from the alternator. Hope that helps!

      ~John

  • As everyone else has said, thank you SO MUCH for all the work put into this post! I’m doing a simplified battery & isolator route (no inverter for the moment) I have a few quick questions:
    1 – how do you determine which gauge wire to connect the blade fuse block to the battery?
    2 – I want to install either a 12v cigarette style outlet or a USB outlet for overnight power but I can’t find any amperage info to determine the wire gauge… any advice there?
    3 – I know for solar you need the charge controller, but

    • Hi Marie, thanks for reaching out! To answer your questions:

      1 – This is based on the max amperage that your fusebox will pull. So you could add up the amperage of the fuses that you’re using in the blade fuse box, and use wiring that can accommodate that amount of amperage. In general, 8 AWG wire is a good bet, which can handle 40-50A of current, depending on what the wire is made of (https://www.cerrowire.com/products/resources/tables-calculators/ampacity-charts/)

      2 – I tend to go thicker with outlets, which will give you flexibility to plug more things into them. We used 14 AWG wire for all of our outlets, which can handle 15-20A of current (you shouldn’t need to go thicker than 12-14 AWG, since you generally don’t want to plug high amperage electronics into a cigarette outlet – if you need more that 10-15A it should be hardwired to the battery). But we fused our outlets lower than that, based on what we were actually going to plug into them. We fused out fridge outlet at 7.5A based on the surge output of the fridge, but we fused all the others ones at 5A, since this is slightly more than the phone chargers that we plug into them will output. USB outlets should tell you the max output – ours would put out 2.1A per USB plug, meaning 4.2A per outlet, so we fused at 5A.

      3 – Your question got cut off here, but I’m guessing you were going to ask if you need a charge controller to just run your outlets/fuse box without solar? The answer is no – you can wire your outlets to your fuse box, and wire your fuse box directly to the battery.

      I hope that helps, and feel free to reach back out if you have other questions!

      ~John

      • Awesome, thanks so much, that’s so helpful. & sorry about the cutoff! I was going to ask if there was another sort of battery monitor that could be installed to keep an eye on the power, but I’d found the answer and forgot to delete that bit.
        Thanks again! Tackling this over the weekend & not a small bit nervous about it, so I can’t thank you enough really.

      • Hey John! One more question for you… I ordered 14 AWG wire to connect my vent fan based on the estimated distance etc per the calculator, but I see that the factory wire on the fan itself is 16 AWG…. is it ok to connect the 14, or should I get some 16?
        Thanks so much!
        M.

  • This is soooo helpful! I actually bought your bare essentials list before finding this page. I have yet to get everything but this will definitely help get it all up and running. My one suggestion would be adding an inverter charger in place of a standard one. Especially if you’re lik me and plan on doing the solar panels down the road. It allows you to not only put out ac current, but also brings it in from a shore power source to charge your battery. Thank you guys for posting all of this!

    • Hi Chris, thanks for commenting, and we’re so glad you’ve found this helpful! Great point about the inverter-charger as well. We cover those in our epic inverter post, but they deserve a mention here as well. If you are regularly able to plug into shore power, inverter-chargers can be a great supplement to a solar setup, or can allow you to charge your batteries before you throw down for solar. Thanks for the input!

      ~John

  • HI John, I bought a Renogy Rover CC and I am having difficulties tightening down the terminal screws. Is the plate on the other end of the screws supposed to push the wire against the plate on the inside of the CC? Are you supposed to tighten the screws clock wise or counter clockwise?

    • Hi Andrew, sorry to hear you’re having trouble! The screw basically clamps the wire down and creates a connection. First you’ll need to completely loosen the screw by turning it counterclockwise. Then, insert the wire end into the hole, and tighten down the screw by turning it clockwise. Hope that helps, and let me know if you run into further issues!

      ~John

  • Hi. I bought one of those battery on-off switches you show in your picture and have two problems with it. First, the posts do not have any positive or negative labels and I do not know if it matters which way I attach the cables. Secondly, it doesn’t lay flat to screw down. The posts stick out the back for me but it looks like you have your screwed down. Does the black sleeve slide back or something, or did you just use extra long screws and leave it sticking out? Or do you have a hole drilled in your board to sync the post in? Thanks for the great article!

    • Hi Carson, thanks for writing! Yes, the amperage does matter, and if you plan on installing a bigger system you will want to go with a bigger charge controller. A 20A charge controller can only handle 20A of current, which affects how many panels you can connect to it and the size of the load you can run from it. The relevant calculation here is amperage = watts x voltage. In a 12V system, you can run a maximum of 240 Watts of solar (12V x 20A = 240W). A 30A charge controller can run up to 360 Watts of solar, and a 40A charge controller can run up to 480 Watts at 12V. Hope that helps!

      ~John

  • Hey there – this is amazing! Thank you for your time and energy here.

    1. I will most likely be close to shore power for most of my time in a bread step van (think more tiny home than campervan), but I like the idea of solar and found a good deal on x100W panels for C$298. How do you connect 110v shore to your system to power lights/fan and to the battery bank to keep those charged?
    2. How did you wire your fan with 14 AWG when it draws 55W/5A? That would have to be a pretty short run, no? I would have to run 10AWG to go 48′ (24′ each way)?
    3. Is it okay to charge phones off of 12V system? I heard it could be some damage? or does it convert from 12 to 5V?
    4. Is it possible to connect a 14AWG to the 22AWG wires on the LED lights? What connector would I use?

    Thank you!!
    Tom

    • Hi Tom, thanks for reading! To answer your questions:

      1. You’ll need a unit that can charge your batteries from shore power. This can be a simple smart battery charger, or a combined inverter/charger unit (which also works as your inverter). If you mainly run 12V stuff, these units will charge your batteries, then your batteries actually run the 12V electronics. If you run mainly 110V appliances, you can get an inverter/charger with a transfer switch, which will actually power your electronics directly from shore power when you’re plugged in, and from the inverter when you’re not.

      2. Our fan only draws 3A at full blast, and we rarely have it up that high. But we do have the fan circuit fused at 5A, which is fine for our 16-ft (8-ft each way) wire run (check out this calculator). According to that calculator, it does look like you would have to run 10 AWG for a 48′ wire run. Good work thinking through your wire sizes – but I would make sure to think through where you’re placing all your electronics to reduce wire runs (if possible).

      3. I haven’t heard of any issues charging phones from 12V USB outlets. But I haven’t seen any USB outlets that actually put out enough amperage to accommodate the quick-charging that modern phones are capable of. We’ve actually taken out all of our USB outlets and replaced them with regular cigarette lighter outlets and quality fast-charging car chargers. These are purpose-built for phone charging, and when technology/connectors change in the future we can just swap out the car chargers instead of rewiring outlets.

      4. This is definitely possible. One way to do it would be to use 16-14 butt connectors (the blue ones), and fold the 22 AWG wire over a couple of times to make a tighter fit. Another option would be to use something like Lever Nuts, which can accommodate different wire sizes.

      Hope that helps! Let me know if you have other questions!

      ~John

      • Thanks John! That’s great info.

        Also – do you recommend two 125ah batteries or one 200ah for a 200W system.?

        Thanks,
        Tom

  • Hi there, I was just curious as to what the Xantrex PROwatt SW Remote Switch is used for and how did you wire it in. Please let me know. Thank you.

    • Hi Andrew, the switch allows you to turn the inverter on/off remotely. We have our inverter mounted in an out-of-the-way location under our bed, so it would be impossible for us to turn it on/off without a remote switch. This is necessary because leaving inverters on when you’re not using AC devices is a significant waste of power, which is really important to think about in off-grid setups. If you’re planning on mounting your inverter somewhere you can easily reach it to turn it on/off then you may not need a remote switch. As far as wiring, the switch comes with a data cable that plugs right into a port on the inverter. Hope that helps!

      ~John

  • Hey there. So i might have jumped the gun and bought a minifridge/stovetop combo, and saw that the voltage rating on the inside of the door is 120v, not 110v. I’ve read elsewhere online that this is essentially the same, and that it just might run a little less efficiently?

    • Hi Brian, you should be good! US voltage is nominally 110V/120V, so it’s all the same deal. Not sure if there’s an efficiency difference, but all AC appliances in the US work on 110/120V. Some people refer to it as 120V, others refer to it as 110V, but it’s essentially the same thing. Hope that helps!

      ~John

  • This guide was instrumental in helping me install my solar. THANK YOU THANK YOU! I do have one question. I have 2 AGM batteries and I am going back and adding a battery isolator and I don’t have enough room on my battery posts for another set of terminals. I did as you suggested and wired on opposite sides of my batteries, all my positives to one battery and all the negatives to the other battery. Since those posts won’t hold any more can I safely wire the isolator to the other 2 posts?

    • Hey Tam, we ran into the same issue with our batteries. We solved it by going to Home Depot and buying a longer bolt so we could fit everything on one post. Wiring the isolator to the other post should work, but I believe it is better for the batteries if everything follows the same “path” – this gets you a more even discharge and keeps the batteries equal in terms of life expectancy. Hope that helps!

      ~John

  • hey guys. what a great post. I’m not working on a van but I am setting up my first small solar system. I keep this open on my phone and read it almost every day.
    so you guys did end up crimping some 8 awhile wire didn’t you? did you do it with a hammer and screw driver? how hard was it?
    thanks a mil for this post

    • Hi Maureen, so glad you found the post helpful! 🙂 We did end up crimping 8 AWG wire. We also recently reorganized/repositioned our electrical area, and we decided to crimp all the wires – 8 AWG, 4 AWG, and 2 AWG. We used a hammer crimp tool to do this (although I have done it with a hammer and a nail punch before, and it worked out). Doing this gave us the flexibility to work on the fly, and everything’s held up so far. I must add that unless you use am expensive hydraulic crimper there is a danger of doing this wrong. There are also a few sites and ebay sellers out there that sell made-to-order crimped cables of any any length, which is a good option if you know how long your cables need to be. Hope that helps!

      ~John

      • what a weird and happy coincidence. I just came across this hammer crimp tool on Thursday and ordered it yesterday.what a great find. hope I can figure out how to do it well. it’ll be a lot cheaper! thanks, john!

  • I just bought a can and Im converting it… Im thinking about the electrical and am thinking it would actually be easier to have two fuse boxes… one on each side of the van… it this possible? Good idea?

    My thought is it makes running the wires a lot easier.

    Thanks

    • Hey Brandon, I don’t think there would be any issues having two fuse boxes and you would be able to have more circuits if you need. But you would still have to run wiring to the battery/charge controller, so it all depends on where you position everything whether having two fuse boxes is easier/cheaper. Hope this helps!

      ~John

  • THanks a million for your guide. It gave me the motivation and courage I needed to tackle our van conversion. I used your guide to order, install and learn everything so it was so much he’ll. The electrical part gave me serious anxiety but you help simplify things.

    I finally got all the wires connected, and the same thing happened. No lights or fans worked. A little frustrating and makes me doubt if I wired properly.
    What setting did you change to remed the load on the controller.

    Thanks in Advance

    • Hey Hai, that’s no fun! The charge controller should be on load setting 17 (on 24 hours per day). If nothing is working at all, then it’s probably either the load setting or something with how the battery is wired. I would double check the battery fuses and make sure any cutoff switches are in the on position. Hopefully it’s something simple, but let us know if you’re having more issues. Best of luck!

      ~John

  • And here I was just wanting to hook a power strip to a solar electric fence charger kit…. A lot more complicated that I was hoping…

    • Hi Sam, don’t get discouraged! Renogy and some other companies make kits that are fairly easy to install, or companies like Goal Zero make all-in-one units where basically all you have to do is plug in a solar panel and you’re good to go (these are more expensive that DIY-ing it, however). Let us know if you have any questions!

      ~John

  • When you guys work on your electrical system, what do you make sure to turn off/disconnect? To your knowledge is it safe to add things to the system (ie plug them into the charge controller/hook them up to the battery) while things are on, or would you disconnect the solar panels/turn off the batteries, etc? You are both so awesome, thank you so much for all the hard work you have put into this website; it has been my go-to for my build and I am so grateful!

    • Hi Sierra, thanks for commenting! We’re always pumped to hear that our site has been helpful!

      As far as working on the system, we just make sure that whatever we’re working on does not have a live circuit. For example, if I’m hooking up our inverter, I’ll either make sure the cutoff switch is set to “off” or I’ll pull the fuse – that way the inverter is not on an active circuit. When wiring things to the fuse box, I won’t put the fuse in until everything is wired up, that way I’m not working on a live circuit.

      If we ever need to disconnect the batteries for some reason (this only happens if we’re adding/disconnecting something that’s hooked directly to the battery) then we always make sure to disconnect the solar panels (pull the fuse or unhook the positive wire from the charge controller), since you never want your panels hooked into the charge controller when batteries are not connected.

      Hope that helps!

      ~John

  • Question I’m having. Would you trust the voltage input on the prowatt sw 1000. When it gets to 12.1 that your battery is at 50% and it’s time to charge.

  • Thank you so much for simplifying this complicated stuff for a layman like myself!

    I wanted to ask for your advice when it comes to wiring one solar panel to a van roof permanently and having another portable backup panel for setting up on site.

    It seems that we won’t be able to fit both 150 watt panels on our roof as previously planned, and are wondering if it would be a bad idea to leave one permanently wired in and have the other on hand for setup at camp. In other words, will the charging capabilities of one 150 watt panel be adequate to supply power to two 155ah batteries and the 30a charger…or is it a bad idea to provide such a little flow of constant solar power? We also have an isolator to help charge when driving.

    Thanks!

    • Hi Julian, we actually ran into a similar issue with our solar. We bought a 400-watt kit (4 panels), but because our roof is a wonky shape we were only able to fit 3 panels on the roof. We carry the fourth in our trunk, and we set it up and plug it in as needed (read more here).

      Having one of your panels detached/portable can actually offer you a lot of flexibility that is nice to have. For example, you can park your van in the shade and stick your portable panel out in the sun, so you’re still able to get a good charge. We also know plenty of people (mostly Westies) who do not have permanently mounted panels at all, and just prop theirs up somewhere at camp. It works out fine for them. Your battery isolator will also go a long way towards keeping you topped off, so you shouldn’t need that panel while you’re driving.

      Another option to consider would be installing a roof rack/ladder rack on your van first. That might give you some additional space where you could mount both panels. If we were to go back and do everything over again, we would have installed a roof rack first – we may have been able to fit all four of our panels up there, and it would have given us an easy spot to attach an awning down the road. We finally installed an awning a few weeks ago, and let me tell you, it was a real pain figuring out how to do it with our high topper!

      Hope that helps!

      ~John

      • Thanks! I guess our main concern was whether the batteries would be getting enough charge while the van is parked on the street while we’re not on the road. We will be using the van only for certain stretches of time and it will otherwise be in storage so to speak. There’s no worry of battery depletion in this case? Thanks again 🙂

        • I wouldn’t think so. If your van is just parked and your not running any loads, 150w should be more than enough to maintain your batteries.

  • Hi, thank you so much for such an informative guide! I had just one question, do you think this set up work with the only change being the smaller 125ah batteries? Thanks again!

    • Hi Josh, glad you found the guide helpful! This setup should work with any size battery bank or solar array. The general wiring and principles will be the same no matter the sizing. Hope that helps!

      ~John

  • Hey John, Awesome post! A few questions…

    1. For connects to anl fuses and cut off switches did you cut wires and ad lug terminals (or ring terminals) yourself? Or did you just buy small lengths of low AWG wire with rings terminals already installed?

    2. Did you end up wiring an outlet from your inverter? I know you mentioned that you were considering wiring directly to an outlet as opposed to keeping the power strip. We are trying to figure out how to wire 2 outlets safely from our inverter. Thinking of calling an electrician….

    • Hi Sean, glad you like the post! To answer your questions:

      1. When we initially did our build, we bought low AWG wire with ring terminals already attached. That worked fine, but we didn’t have much flexibility with wire lengths. We recently did some rearranging of our electrical setup to free up more storage space, and for the redux we bought wiring (we used 2 AWG, 4 AWG, and 8 AWG for various things) and crimped terminals on ourselves with a hammer crimper and adhesive shrink wrap. The crimper cost about $20, so it was probably a wash in terms of a cost comparison with buying ready made wire. There’s also the danger of not crimping the terminals on properly and something coming loose, but it’s working out so far.

      2. We decided to plug in two 3-outlet strips and mount them on either side of the van. It’s more practical and sturdy than our previous setup, but we did not wire in permanent outlets. We were new to electrical before we built our van, and 110V still scares us a bit.

      Hope that helps!

      ~John

    • Hi Sean, glad you like the post! To answer your questions:

      1. When we first installed our electrical, we bought premade lengths of wire with the ring terminals attached. It worked fine, but we were limited on wire lengths. We recently reconfigured everything to free up more storage space, and this time around we bought cable and crimped on terminals ourselves with a hammer crimper and adhesive heat shrink. The crimper was about $20, so it was probably a wash in terms of cost. Plus there’s always the danger of crimping incorrectly and something coming lose, but it’s worked out so far.

      2. We decided to go with two 3-outlet strips that we mounted on either side of the van. It’s much more practical and sturdy than our previous setup, but not an actual outlet. We didn’t know anything about electrical before we built our van, and 110V still scares us a bit.

      Hope that helps!

      ~John

  • For now I’m only using a battery isolator for charging. Would in need to connect my fuse box to a charge controller or can I just connect it to the batteries?

    • Hi Rob, you only need a charge controller if you have solar. In your case, you can just attach your fuse box directly to your battery terminals. If you choose to add solar in the future, then you would run everything through the charge controller. Hope that helps!

      ~John

  • What type of switches did you use to cut power to the solar panels, inverter, and charge controller?… Also, did you test any of your electronics before installing them? I bought the same solar kit as you guys and I am curious what size wire you used from each panel to your branch connector and then what size wire to the CC? Please let me know. Thank you so much. You guys are awesome and amazingly inspiring.

    • Hi Andrew, we used this switch. This one is nice because it’s very high quality, turns nicely, and has the ability to surface mount.

      We didn’t test any our electronics before installing them initially. We recently did some reorganizing of our electrical area, and after I reconnected everything our inverter wouldn’t turn on. Xantrex sent me a warranty replacement, but that one wouldn’t turn on either. Through some testing with a multimeter and process of elimination, I was able to determine that one of the cables was bad. Swapped out the cable and the inverter worked! So having a multimeter on hand is definitely a good idea if you need to diagnose issues.

      Our solar kit came with 8 AWG wire, which we used to connect the panels to the charge controller and the charge controller to the batteries (and the fuse box/negative bus to the charge controller). Wire size should be based on the current going through them. We have a 40A charge controller, so everything is sized for 40A – which means 8 AWG wire. Here’s a helpful chart showing ampacity ratings for different wire sizes: https://www.cerrowire.com/ampacity-charts

      I hope that helps! Good luck with your build!

      ~John

  • Hello. thanks for writing such a detailed post. I have 1 question, do I need an inverter to charge a laptop? i am planning wiring outlets and stay away from having a inverter. is this possible?

    • Hi Jared, I don’t know of a way to charge a laptop without some sort of inverter, but if all you’re doing is charging a laptop you can buy a small inverter that plugs into a regular 12V outlet like this one. I would make sure your use thicker wiring for the outlet you’re plugging the inverter into, just so you don’t overload the wiring. Hope that helps!

      ~John

  • hey guys love your page, what kind of heavy duty switch did you use for your inverter, I’ve been looking all over for one without any luck not sure about the specs for it? Is the switch a must have for that part of the circuit?

    • Hi Jen, thanks for the comment! We used this heavy duty on/off switch from BEP for our inverter. It’s very high-quality, rated for 300A, and allows you to surface mount it, which makes installation easy. There are less expensive switches out there, but you sacrifice the surface mounting ability. In my opinion, having a master on/off for the inverter is essential, since it’s a high voltage component and having a cutoff is good just for safety. Hope that helps!

      ~John

  • I’m going to start by echoing the comments of everyone else… this is an insanely awesome post and has given me the confidence to tackle the electrical myself (while checking with some qualified individuals along the way of course)! Thank you!!

    I’m curious how often you use your 4th solar panel. I was thinking of going with 3 panels along with a battery isolator and possibly adding shore power for a backup, but you seem to be entirely off the grid which is super appealing. Do you find that you use your 4th panel often? Is it mainly just when you are in shaded or partially clouded areas? Thanks for the insight!

    • Hi Supriya, thanks for the kind words on the post! We just hope it helps others get started on their own journeys 🙂

      We don’t use our fourth panel every day, but we do break it out when we’re in one spot for more than a few days, especially if we’re in a shaded/overcast area. I wouldn’t call it a necessity and we would probably be fine without it, but it can be nice to have if you’re stationary (i.e. not using your battery isolator) in shaded areas for longer periods. If you’re moving around more frequently and/or if you’re staying in the sun, then it’s less needed. Hope that helps!

      ~John

  • hey this post has been a life saver thank you so much, I’m curious if we are not ready to go solar can i just wire the battery switch to the positive connection in the fuse box and the negative battery to the negative bus bar and leave out the charge controller?

    • Hi Jenny, yes, that is exactly what you would do! That way your aux batteries will be powering your basic electrical, and you can always add solar later. So glad this post has been helpful, best of luck with your build!

      ~John

  • Love the break down. I use to have a travel trailer and my batteries would die all the time. I didn’t know much about solar at the time, but now I do. I have two solar panels on my Winnebago ERA 170M that keep my batteries charged. Still trying to understand my full set up as it came from the factory that way. Zamp charger and maybe 100-150 totaling 200 watts to charge. I have found I don’t get enough power from the 12 volt outlets to power some things. Still learning how to power everything without the generator. At least as much as I can.

    • Hi Brandi, learning about and improving our rigs is always a continual journey. Especially with electrical – there’s so much to think about and so much to learn! If you’re having problems with your batteries dying and your outlets not powering things, I wonder if your batteries are shot – completely draining lead acid batteries can damage and weaken the cells. Good luck with your rig!

      ~John

  • Hey guys!

    I’ve got another question for you, this time having to do with all this electricity! It doesn’t look like you wired your system to have an option for charging via an extension cord or rv hook up. Did I miss this? Do you think it would be worthwhile to work that in?
    I plan on being parked frequently at friends houses where I would have an option to plug into their power with an extension cord.
    As for power needs I will only need to power led lights, a 12v fridge, and charge my phone, (Possibly charge my laptop as well).

    • Hey John, that’s correct, we do not have a shore power hookup. As far as whether it’s worthwhile – I think that depends on your situation and what other charging methods you have.

      We have a ton of solar plus a battery isolator (and big batteries), so we’re almost never in a situation where we don’t have enough electricity to meet our needs and keep our batteries charged. We also don’t do much driveway camping, so making sure our rig is fully off grid was a priority for us.

      That said, having the option to plug in can be a good backup, especially if you have less solar/battery capacity. And if you know you’ll frequently be places where you can plug in, it would definitely make sense, and you might even be able to save some money on solar (which you can always add/increase later on if you go smaller in the beginning).

      To rig your van for shore power, you would basically need a smart battery charger like this one or a combined inverter/charger like this one (which takes care of both the inverter and the battery charger). You would also need to install an RV power inlet like this one on your van. To hook this up, you would wire the power inlet to the battery charger, then wire the battery charger directly to your batteries.

      Hope that helps!

      ~John

      • Thanks John!
        Just ordered everything but batteries & an inverter! I’ll likely go with the inverter/charger combo and wire in an inlet attached to the outside of the van.
        Two more quick questions.
        First what are your thoughts on this battery? https://www.thesolarbiz.com/batteries/upg-agm-group-30h-12-volt-110ah-battery.html
        AGM, Deep cycle, 12v 110AH for $156 seems like too good of a price to be true, especially compared to the Vmax 125AH. There are also various other batteries on that site, Amazon, and Renogy’s website that cost less per Ah than the Vmax. Are they that much better?
        Second, you set up a battery switch between the battery and your charge controller, in case you need to shut off power to the battery. However, I’m don’t understand the purpose to that switch considering the stipulation of not having the panels plugged into the charge controller without the batteries also plugged into the charge controller. If you were to turn the switch wouldn’t the controller overload and, as Renogy says “explode”?
        Cheers! And thanks again!

        • Hey John, I do know that brand has been around for awhile so I don’t think you would go wrong with it, as long as it’s a true deep cycle battery. VMAX supposedly uses thicker lead plates, and they have a good reputation for reliability and quick charging among solar and off-grid enthusiasts. We’ve had a good experience with ours, but it’s been awhile since I’ve researched other brands. We’re gearing up to do a detailed post on different battery options, though, so I’ll be taking a deep dive into tech specs for different batteries soon.

          As far as the cutoff switch – the idea was to be able to disconnect the batteries in case we needed to work on the system. But you’re right, we would need to disconnect the solar panels before we flipped this switch (we usually unhook the wires from the charge controller or pull the fuse first).

          ~John

  • I have read this post so many times trying to wrap my head around building an electrical system and I wanted to say thank you so much for putting it out there! We are doing the simplified version of your build out with the battery isolator and maybe a battery charger for when we are around shore power. We also got the Victron BMV-700 to monitor the battery. It seems pretty straightforward the way you guys do it, having everything go through a charge controller but I’m a little confused on what to do if that piece is missing from the equation. How would we hook up the fuse box and negative bus bar for the other appliances? Is it okay to have it run directly from the battery without the charge controller in between? Would we determine the gauge of that wire going to the fuse box by figuring out how much total draw the fuse box will be have? How does the battery monitor get set up in all of this? Is the shunt wired directly to the battery terminal as well, or does it go through the negative bus bar? I saw that you mentioned you guys ended up installing one of those – I would love to know how you did it. What size wire did you use for attaching the shunt to the battery? Finding the amperage on it was a bit confusing. Do you think we would be better off using a charge controller even without the solar panels attached? Sorry for the loads of questions. We would be forever grateful if you could help us out!! Thanks again for all you do for this community.

    • Hi Tess, so glad our post has been helpful! To answer your questions:

      If you don’t have a charge controller, you can simply wire your fuse box to the positive terminal of your battery, and the negative bus to the negative terminal. You can always add solar and a charge controller later, and rewire everything through the CC at that point.

      You are correct about deciding on the wire gauge – add up the max current of everything you are running, then choose a wire gauge thick enough to handle that current (here is a helpful wire gauge ampacity chart) You likely won’t be running more than 40 amps of 12V load, so 8 AWG wire is a good bet.

      We also have a BMV-700 monitor. Victron has a video on their website showing how to wire it. Basically, the shunt goes in between your battery’s negative terminal and the vehicle ground connection. So, you would run ground a wire from the vehicle chassis to one end of the shunt, and a wire from the other end of the shunt to the battery’s negative terminal. The shunt also includes a small positive wire to connect to the positive battery terminal. After that, just plug the monitor into the shunt, and you’re good to go!

      Hope that helps, and best of luck with the build!

      ~John

      • Thank you so much for your detailed response! Very helpful indeed. One more question – what size wire would you recommend for the shunt / grounding wire ?

        • The grounding wire should be able to handle all of the current going through the system, so the general rule of thumb is that it should be at least as thick as your thickest positive wire. We used 2 AWG wire for our grounding wires, which matches the thickest wire in our system (we wired our inverter with 2 AWG wire).

  • This is the most detailed and comprehensive post I can find on the internet – thank you! Do you happen to have a wiring diagram for LED lights? In your diagram where it says “to lights etc”, I’m trying to understand the details and how you wired your lights, dimmer, etc. Any help is much appreciated!

    • Hi Shohei, so glad you find this page helpful, we put a lot of work into it and helping other vanlifers is our goal! 🙂

      We don’t currently have a diagram of how we wired our lights, but we’ve had a few questions about this so we will be sure to add one in the near future. I can try to describe it to you here, though.

      We wired our LED lights in parallel, meaning we connected all the positive wires together along with the appropriate wire from the dimmer switch, and all the negative wires together along with the appropriate wire from the dimmer. You can also wire LED lights in series: connect the positive from one light to the negative on the next, and so on. You will be left with a string of lights, and should have a free positive wire on one side and a free negative wire on the other side, which you would wire into the dimmer. This would probably be a little easier than wiring in parallel. Here’s a post that explains a bit about the differences: https://www.ledsupply.com/blog/wiring-leds-correctly-series-parallel-circuits-explained/

      Wiring the dimmer:
      This is a bit confusing since the dimmer we used does not follow the red=positive black=negative convention that every other electrical component uses. Here’s the diagram that is included on the package:
      Dimmer wiring diagram
      Basically, the positive wire(s) from the lights goes to the white(+) wire on the dimmer, and this connection is combined with another wire that connects to to your fuse box. The negative wire(s) from the lights goes to the red(-) wire on the dimmer. Finally, the black(ground) wire on the dimmer connects to your negative bus.

      I hope that helps! Let me know if you have further questions, and best of luck with your build!

      ~John

      • Thanks, John. That’s super helpful! How/what did you use to wire together all the positive and negative wires? Having no electrical experience, this and all your other posts have been instrumental thus far!

        • It depends how many wires you’re connecting. If you’re just joining two wires together, a simple butt splice works fine (add heat shrink over it for a bit more security, and to make it look better). If you’re joining multiple wires together, then I personally think the best method is to use something like Lever Nuts. Just insert the wires, close the lever, and you’re good to go. The lever nuts I linked to have ports for 5 wires, but if you search lever nuts on Amazon or Google you can find ones that have as few as 2 ports and as many as 8 ports.

          We didn’t know about these when we did our wiring, so we ended up using basic wire nuts to join our wires. Wire nuts are NOT intended for automotive use, as they can come loose from the vibration of driving, but we wrapped our joints in electrical tape to make sure they would hold and we haven’t had any issues. But if we were to do it again today, we would use lever nuts (in fact, we’re doing a little reorganizing of our electrical to make our storage area more space efficient, and I may rewire the lights with these).

          Let me know if you have other questions, I’m happy to help! 🙂

          ~John

  • I’m so confused and not sure you could help because your system seems to be working. So I literally wired everything the exact same way as you, but when it comes time to connect the fuse box, the charge controller reads ERR 4. So I called Renogy and they basically said I’m not supposed to run a fuse box to the charge controller so basically I have no idea what to do because your fuse box seems to be working fine

    • Hi Melissa, sorry to hear you’re having trouble! It’s tough for me to diagnose without seeing your system. Looking at their manual, error code 4 indicates a short circuit, so there must be some kind of short in your wiring somewhere. Check around for any loose connections or exposed wiring making contact with metal, which could cause a short.

      Question: Does your fuse box have connections for both positive and negative? Most blade fuse boxes, like ours, only have positive connections for your loads (like your lights, outlets, fan, etc). But you also need to tie in the negative to complete the circuit. We have the negative wires from our loads tied into a negative bus bar, which is then wired into the negative load slot on the charge controller (the fuse box is wired into the positive load slot). Not sure if that’s your problem, but this was a point of confusion for us when we were wiring our system.

      I’m not sure why Renogy told you not to connect a fuse box, as there is literally no other way to properly wire an electrical system. Fuses are an important safety measure, and since the charge controller only has one +/- input for the load, you need to combine all of it somewhere, which would mean a fuse box.

      I hope that helps, and feel free to reach out if you have further questions.

      ~John

    • I realize this is an old post and question, but in case anyone else reads it I will offer a probable cause. The load – terminals on the MPPT controller cannot be connected to the chassis or to the battery negative. The output from the MPPT controller has a floating 0V reference. What that means is you will get 12 volt between the load +/- terminals, but not from the battery negative post to the load + terminal, nor will you get 0 volts from the load – terminal to the battery negative post. If you connect the load – terminal to battery negative or to chassis ground, the system cannot work. That is why Renogy said it is not recommended to connect as you show. Normally you would connect the fuse box directly to the battery.

      • Hi John-

        Great work! I am restoring an old Airstream trailer and building the electrical system from scratch. It seems as though your system can stand alone without either shore power connection or connection to the vehicle alternator. Any reason I should be considering connecting to the alternator? And any special insight into how that wiring diagram might look?

        Many thanks!

        Brent

        • Hi Brent, when we originally installed our system it was completely standalone, but pretty soon after we realized we also needed a way to charge from the alternator. Having this much solar is awesome – but only if we’re getting enough sun. We found that if we’re spending a lot of time in forested or heavily overcast areas, our batteries dip down to the 12.0V-12.2V range after about five days or so. But since we added a battery isolator, we never have to worry about it because we’re topping off whenever we drive.

          We actually wrote a blog post about installing a battery isolator that goes over installation instructions (no diagram, but we’ll be adding one in the future). Basically, the isolator sits in the engine bay and connects to the positive terminal on your starting battery as well as chassis ground. Then, run a long battery cable from the isolator, underneath the vehicle, and up to the positive terminal on your aux battery. Both batteries should be fused with 150A inline fuses/breakers.

          I need to update the post, but we recommend and have switched to the Wirthco Battery Doctor 125/150A isolator, since it’s inexpensive and has the ability to reverse the current flow and jump your starting battery from your aux battery – which is a kickass feature.

          Hope that helps!

          ~John

          • Great help, John, Thanks. Since the amperage running from the alternator to the house batteries would be significant, it sounds like this isn’t something that can simply be carried through the wiring harness to the trailer, so I imagine I’d have to set up a separate plug in connection at the trailer hitch. Does this make sense?

            Thanks again.

            Brent

            • Yeah, I’m not sure what size wire your wiring harness uses, but Wirthco recommends fusing both batteries at 150A and using 4 AWG wire for batteries mounted in the rear. We basically ran a cable under our van and up through a hole that we drilled through the floor. I would think that a separate plug in might make sense, but I don’t have a lot of experience with setting this up on a trailer. Hope that helps!

              ~John

  • Thanks for the post. Amazing write up and descriptions. I have a few questions.
    1) What’s the wire size you used to connect the inverter to the battery?
    2) what’s the wire size you used to grounded the inverter and battery
    Thank you guys 🙂

    • Hi Marco, glad you enjoyed the post! We used 2 AWG cable to wire the inverter to the battery and to ground it. If I remember correctly, the instructions for our inverter recommended using 0 or 00 AWG wire for the battery connection with a 150A fuse. But at the time we did not have easy/cheap access to 0/00 cable, so we went with 2 AWG cable and a 100A fuse to compensate. Thicker is usually better when wiring an inverter, but make sure to read the instructions for your specific unit, and to use fuses that are appropriate for the wire gauge you’re using. Hope that helps!

      ~John

  • Hi John,

    Have you had any issues with charging 5v batteries into your 12v USB outlets? An example would be phones, fitbit, gopro, kindle, which from what I have seen all require a 5v power supply.

    Thanks,
    Luke

    • Hi Luke, we did not have any issues with it. While our outlets accepted 12V power, I believe USB in general is 5V, so the outlets likely converted the voltage internally before outputting it – otherwise USB devices would not have worked.

      We’ve actually switched out all of our USB outlets for 12V cigarette lighter outlets, and we just use car charger plugins for our phones/devices. We’ve found that this allows us to stay on top of changing technology better. The amperage output of high speed charging seems to constantly go up, but it’s really tough to find actual USB outlets that are compatible with quick charge, etc. We also switched to phones that have USB-C outlets, so we have less of a need for USB. Having the ability to just plug in a car charger into a standard 12V outlet lets us upgrade/switch out the car charger unit as technology and connectors change, as well as take advantage of quick charging.

      Also – we were not able to find ANY 12V USB outlets that did not have some sort of bright LED light indicating that the outlet had power. It’s really tough trying to sleep when you have a bright blue light shining in your face, and remembering to cover up all of our outlets with clothing before laying down was a pain. This is probably the biggest reason we switched out our USB outlets.

      Hope that helps!

      ~John

  • Hey John!

    Thank you so, so much for all the work you both have done on the site and on these resources for our community. It’s so hugely helpful, and of course every chance I get, I make my amazon purchases through your links!

    I read down through many prior comments, but I couldn’t see if this was answered yet: how did you rig your fridge? I assume it isn’t powered through AC via the inverter, so does that mean it’s powered through the fuse box? Or perhaps directly into the battery via one of these guys? https://www.amazon.com/gp/product/B00G8WLW2Y/ref=oh_aui_detailpage_o01_s01?ie=UTF8&psc=1

    Just looking for some clarity- I’m in the thick of a remodel and redesign of both furniture and electrical after 5 months of daily living, and as my rig (and solar setup) is almost identical to yours, I’m curious what path you guys took.

    Thanks in advance for any info at all!

    Cheers,
    Emma

    • Hi Emma, glad our site is helpful and thank you so much for the support! For all of our “plug in” stuff (fridge, small box fan, cell booster, etc) we installed several 12V cigarette lighter outlets throughout our van. These are connected to the fuse box. We just plugged our fridge into one of these outlets. The product you list would work as well, but if you’re running things through a fuse box it might be tidier to wire an outlet through the fuse box (there are also surface mount 12V outlets if you don’t want to get into drilling holes to mount an outlet). I know some people directly wire their fridges to their batteries, but I think that involves a bit more complicated wiring. Hope that helps!

      ~John

  • Wow! This is the article I’ve been dreaming of! Thanks so much for the totally thorough detail. currently doing the wiring plan for a van I just purchased and this article will really help me out. Haven’t read the whole thing yet so I’ll let you know if I have any questions. Thanks so much.

      • Hi John Thanks for the awesome article and fantastic website. This is my favorite site for Van living. I have a few questions after reading your article ( and, yes I know you’re not an electrician. Lol)
        There is no mention here about how you run the solar wires from the roof to the inside of the van. I’ve had solar panels on my minivan for years but I ran the wires through the little rear wing window. Now that I have a cargo van, I would like a more waterproof install since the window leaked a little if driving rain hit the car. Do you have a link to another article on that? My other question is about AC Outlets. I would like my little van to look as nice as possible so was planning to use Outlets. What I don’t understand is what is happening to the inverter when you do that. Is the inverter left on all the time? If so, is it constantly drawing power or only when something is plugged in and turned on? If drawing power all the time, then I need to include that in my calculations of needed amperage.
        Oh, I do have another question. I am going to install a Dometic Fridge, which I have never had in my van before. I want to do a very minimal install right now. & slowly build out. I am disabled and it is very hard for me to get things done so I’m quite slow. Do you think I need to absolutely have a fuse box from the very beginning to run A fridge and a fan? Right now I just have my inverter hooked up to my battery and I plug my devices into the inverter. I have not had any continuously running devices/appliances on my battery before.
        Thanks so much for all of your awesome giving to the van life community. Luv ya!

        • Hi Cza, I’m glad you’ve been finding our site helpful! Our goal is breaking down knowledge barriers to help others embark on their own vandwelling journey, and we love hearing that we’ve been of use!

          To answer your questions:

          –We have another post that details how we mounted our solar panels and ran the wiring inside (read it here). Basically, we drilled a hole in the side of our high topper for the wires, covered it up with this wire gland, and sealed everything.

          –We turn our inverter on and off as needed to preserve power. Since we have our inverter tucked away under our bench, we hooked up a remote switch that we mounted next to our light/fan switches, which allows us to easily control our inverter. If you have a different brand of inverter, you can check to see if they have a remote switch, or mount it in an easily accessible place.

          –I would not skip fuses when you’re working with electrical. Fuses are an important safety feature that prevent short circuits and electrical fires. But you definitely don’t need to spend a lot of money here. There are plenty of inexpensive automotive fuse boxes and blade fuses on Amazon and at auto parts stores that work just fine. But I definitely wouldn’t skip this, just for safety reasons.

          Best of luck with your build! Feel free to reach out with any other questions!

          ~John

  • Also with your fuse holder on the solar line, How did you go about splicing that? did you have to solder?
    Thanks

  • Howdy folks, this page has been such a help in my astro build.
    I am running wiring for the lighting, I have the acegoo lights and same dimmer switch as you.
    could you give a quick overview on how you ran lighting wiring from your fuse box, bus bar and load?
    I have read that these lights need to be wired in parallel, I am looking at soldering T splices to make this happen.
    Thanks for all of the knowledge,
    Ralph

    • Hi Ralph, glad our page has been helpful! For the lighting, we ran a negative wire from the bus bar and a positive wire from the fuze box up to the dimmer, where everything wires together with the lights. The wiring for the lighting/dimmer gets a bit confusing, because the dimmer manufacturer decided to use wire colors that are the total opposite of what you would think (the positive wire is white, while the negative wire is red). Basically, the positive wires (red) from the lights AND the positive wire from the fuse box connect to the positive wire for the dimmer (white). The negative wires from the lights (black) connect to the negative wire from the dimmer (red). Finally, the negative wire from the bus bar connects to the ground wire on the dimmer (black).

      As far as connecting/wiring the lights in parallel, we actually did this at the point of connection with the dimmer switch using wire nuts/twist connectors, then wrapped the connection in electrical tape. Wire nuts are NOT meant for mobile applications because they can easily come loose via vibration, but taping it up eliminates a lot of the stress on the joint. Still, we don’t necessarily recommend going that route. Something that involves crimping or soldering would be much more secure. I had an appliance repair electrician recommend these to me: https://www.adafruit.com/product/874

      Hope that helps!

      ~John

      • John,
        Thanks for the quick response, you guys are great!
        So let me make sure I totally understand what you did. You ran 18awg wire to each light individually and used a wire nut to make your connections to each at the dimmer switch? and at this same point was your tie in with the fuse box/ bus bar?

        Ive been using this page a ton in the build process and have tried to give back by purchasing through your affiliate deal whenever possible.
        Thanks!

        Ralph

        • and one other clarifier,
          the ground line on that dimmer switch, you just sent that back to the bus bar on its own line? (14awg?)

          • Last clarifier,
            the wires from the bus/ fuse -> to dimmer switch,
            you used 14awg?

            thanks

            • Correct, we used 14 AWG. But the sizing of your wiring should be based on the amount of current you expect to flow through it – then choose a wire size that’s rated for that amperage.

          • Yes, the ground line just goes straight back to the bus bar. The other two wires are the only ones that connect to the lights. And we used 14 AWG wire for this.

        • That’s correct. Although we have been “yelled at” by a couple of electricians for using wire nuts in a vehicle, so we can’t necessarily recommend that route. There are probably better ways to make that connection, but we made sure to reinforce it with tape and haven’t had any issues. Glad the page has been helpful, and thanks for the support! 🙂

  • Hi just wanted to say thank you so much for this guide it has been immensely helpful as I set up my system. Hopefully will be installing this weekend! Check out my progress @kellenbusby.

    One quick question. How did you determine the wire size for connecting your batteries to your charge controller? And also, I could be wrong but the battery wire that’s connected to your charge controller in your pictures looks much thinner than 4awg. I’m questioning whether or not 4awg wire will fit in the renogy mppt charge controller.

    Thanks so much!

    • Hi Kellen, Glad our website has been helpful! We actually used the 8 AWG wire that came with the solar kit to connect the negative terminal on the charge controller to the negative battery post, and the positive terminal on the CC to the cut off switch that we included. We used 4 AWG wiring to connect the switch to the fuse, the fuse to the battery, and to wire the two batteries in parallel. I need to update this post to make this clearer.

      The minimum wire size as well as the fuse sizes is based on the amperage rating of the charge controller. We have a 40A charge controller, so we need wiring that can handle 40A of current at a minimum (so the smallest you can safely go is 8 AWG). We went with 4 AWG to fill in the gaps because at the time we did our install we were working under the assumption that thicker is better, and we didn’t see a disadvantage to it (aside from the wires being tougher to work with). But as long as you’re using wiring that is rated to handle the current going through it (and using the correct fuse sizes) then there’s not a big reason to go thicker than necessary.

      Here’s a resource that shows the amperage rating of different wire gauges:

      https://www.cerrowire.com/ampacity-charts

      I hope that helps! Good luck with your build!

      ~John

      • What about batteries quite a distance from the charge controller? Mine may be 8-10 feet away (haven’t installed yet, but will definitely be a distance)… I was planning on using 8awg before, but how should I account for distance in my wire selection? Thank you for this incredible guide, I keep coming back to it!

        • Hi Shay, thanks for reaching out! If your batteries will be 8-10 feet away from your charge controller, I would recommend going with 6AWG wire (assuming that you’re putting 30A through to the batteries). This calculator can help you determine the wire size you need. Important note: when you enter the “length of conduction” (i.e. wire length) make sure to add the length of both the positive and negative wires. So, if your batteries are 10 feet away from your charge controller, your total conductor length is 20ft (10 feet positive + 10 feet negative = 20 feet total). Here’s another visualization of wire size requirements in chart form. Hope that helps!

          ~John

  • hi! i am curious as to how you hooked up the fuse box and inverter from the battery. i see a few pictures of the battery but i am curious of the tools and supplies necessary to do so! thanks for all your informative pages 🙂

    • Hi Brynne, the fuse box is actually wired to the solar charge controller. As far as tools, all you need there is a screwdriver to screw the wiring down to the terminal on the charge controller, and a socket wrench to connect the other end to the post on the fuse box. The inverter is wired directly to the battery. There is a wire running from the negative battery post to a negative terminal on the back of the inverter, and another wiring running from the positive post on the battery, to a fuse, then to the positive post on the back of the inverter. You’ll need a socket wrench to connect wires to both the battery and the inverter. I hope that helps!

      ~John

  • Hello! Thank you for all this information!
    I am wondering about the whether to put the wiring in before or after insulating our van. We live in Montana and it gets well below zero in the winter. To combat that we will have 5 inches of wool insulation on all sides of the van. Is there any worry about wires freezing, breaking from cold or not working in general, if we install them first?

    • Hi Kayli, from what I’ve read, a cold/frozen wire should actually conduct electricity better than a hot or room temperature wire, so there’s not a disadvantage for you as far as the climate goes. But one thing to think about is if you ever have to work on or replace your wiring, having it behind your insulation will make that more difficult. That said, we ran the wiring for our ceiling lights before we insulated or put up our ceiling and we haven’t had any issues. Hope that helps!

      ~John

  • Hi

    Thanks for this. Really help me.

    Question. Why you use a 2 awg for ground connection for the batteries. And the red one is 4agw between charge controller and batteries. They doesn’t have to be the same? Same amp (your case 155+155)

    Thanks

    Fran

    • Hi Fran, the ground wire should be equal or thicker to the rest of the wiring you use – so it does not have to be the same size, but it should not be smaller. We went with a thicker gauge for additional peace of mind, because our ground wire runs to the vehicle chassis were pushing 2-3 feet, and we wanted thicker gauge to compensate for the length of the wire run. I hope that helps!

      ~John

  • Since the charge controller is not supposed to be hooked to panels without battery would it make any sense to have the on/off switch instead located between the solar panels and the controller?

    • Hi Simon,

      I think it would make sense to also have a switch between the solar panels and the charge controller. We use the battery on/off switch to cut power to the loads if/when we need to work on the system, but as it stands now we either unhook the solar panel wires or pull the fuse first. But a switch would also be a good addition.

      Thanks,
      John

  • This guide is a lifesaver!!! Thank you so much for this. I have one question: you say you have to connect the batteries to the charge controller before the solar gets connected to it otherwise it might blow up. Does that mean after everything is all connected together, what if for some reason you have to use the kill switch thingy, and stop the current going from the batteries to the charge controller? Would you have to disconnect all the solar panel wiring first?

    • Hi Angie,

      I’m glad that our guide is helpful! With regards to the kill switch – we do have to pull the wires or fuse fuse the solar panels before we use this (or, do it at night when there’s no sun). We’ve rarely used it, but it’s good to be able to cut the feed if we need to work on the system. If you are so inclined, you could also add a kill switch between the solar panels and the charge controller. Hopethat helps!

      ~John

  • all solar set ups i’ve seen so far direct all the working current through the charge controller. If I am planning on adding solar, does it make sense to buy the charge controller now and wire it into the system, so that once I do get the panels i can plug them in and go?

    • Hi Jack,

      Having the charge controller pre-wired would probably make installing your solar panels easier, because you wouldn’t have to rewire everything to your battery. One thing to consider, though, is cost. Buying a complete kit like the ones from Renogy may give you some cost savings over buying the charge controller and the panels separately. I would price out the components separately and see how that compares to the cost of the kit, then from there you can decide if the cost difference is worth the ease of adding solar panels later. Hope that helps!

      ~John

  • Nice system! I did the 400 kit too and it’s worth the peace of mind on long outbacks.
    Nice storage solution for the mobile one.
    A H5 to adventurevanman for high lighting
    The great detail you share .
    Q – On your diagram, u have the fuse for the inverter on the neg wire. Shouldn’t it be on the pos wire?
    It’s great to see all the instructions in one place !
    Thank you !
    The Sub-Urban Mama
    Converted Suburban 😉

    • Hi Graci,

      You’re right, the fuse should be on the positive wire. Thanks for pointing out the error! I’ll fix that as soon as I get a chance. Glad you enjoy our site, we work hard on it! And definitely an H5 to adventurevanman!

      Take care,
      John

  • Great post! Very thorough. I did want to point out something a little confusing. You wrote, “Per the tech specs on our Acegoo 12V recessed LED lights, they have a max current of 3V per light. To convert that to amperage, we divide by the system volume (3V / 12V = 0.25A).” After a little head-scratching, I figured out that I think you mean, that each light draws 3W, not 3V. So your equation should be 3W/12V = 0.25A.

    • Aha! Good eye! I’ve changed this to 3W, as it should have been. Thanks for catching that typo!

      ~John

  • Question for you guys!
    I’ve been doing some research on inverters because of high price ($285) of the one listed. I found a 2000W Inverter on amazon and am curious if you see this compatible?
    We are essentially following your set up, just customizing it. We will be running a Renogy 200W to a 20A Rover MTTP Charge Controller connected to two 12V-155ah VMaxx batteries.
    This is the inverter we found with double the output for nearly half the price ($140). It comes with a crap charge controller we would obvious ditch for Renogy’s.. but any opinion on this is greatly appreciated!!
    https://www.amazon.com/gp/product/B077HHFDZV/ref=ox_sc_mini_detail?ie=UTF8&psc=1&smid=A1SK9IS6JDBCLC

    Can’t thank you enough for this informative post!

  • First let me say what a great resource this blog post is!

    So I have come across a problem. I have my inverter and fuse box wired into a marine grade on/off switch (like the ones you have used). The switch allows me to isolate the inverter and fuse box and can also turn on both.

    The inverter works fine however when I hooked up a test light to the fuse box I got no power.

    I checked all connections and even bypassed the larger 120 fuse (went straight from switch to fuse box).

    I am lost!! Help!!

    I have used the same fuse box and wires you suggested in post.

    Best,

    Matt

  • Awesome entry. Probably one of the most thorough yet easy to follow entries on electrical I’ve come across.

    Quick questions, it looks like the charge controller in your pictures is different than the kitted item in the Amazon solar kit. Did you go a different route personally or is the one in that kit sufficient?

    Also, I’m stuck in the south so the Alabama heat has an air conditioner in my electrical plans. Have you considered adding a 30A RV shore power connection to plug in on a grid? Not finding as many resources for that. I’m not wanting to expend the $$ to maintain an off grid capable AC so I’m thinking of keeping a plug in option for when it’s available to keep cool.

    • Hey Andy, glad you like the post! We bought the same kit that we linked to in the post, but since then Renogy updated the charge controller. Installation is the same, but unlike ours the new one has a built-in display. As far as hookups, we don’t run an AC so we haven’t had the need. But you would basically add on a combo inverter/charger unit that is both an inverter, and allows you to plug in for charging. Renogy offers a 1000W unit and a 2000W unit. Hope that helps!

      ~John

      • That is the exact piece to the puzzle I couldn’t figure out. That’s pricey, but perfect! Thank you so much. I have almost my entire build planned out, next step is to buy the van and then execute. I’m excited!

  • A tip for attaching large battery cables to the sheet metal body, after attaching the lug with a self tapping screw through the hole in the lug, put another self tapping screw through the lug outside of the hole (drill through the lug). This will prevent the lug from rotating and loosening. Be sure to remove the paint from the sheet metal before attaching any high current cables. If installing 120v power outlets, don’t use standard house wiring. Don’t use any solid wire. Use only stranded wire. 3 conductor stranded wire that looks similar to romex is available and makes the job easy.

    • Yes, we keep the inverter off when it’s not in use. We have a remote switch for it that’s mounted by all of our light switches, so we just turn it on when we need to use it, and turn it off when we’re done. This is mostly to preserve power, as the inverter will draw some power when it’s on. Hope this helps!

      ~John

  • your guide is making my van build doable!! without this i would be seriously struggling and likely have to hire an electrician for help. Thank you!!

    question! what is the purpose of the kill switch between the battery and the charge controller? It seems like a hazard if Renogy says that wiring the panels to the charge controller without the battery connected could cause explosion. Seems like an accidental flip of that switch could put your system down.
    what was the thought behind this?

    thanks!!

    • Hi there, glad you like the post! The idea behind the kill switch is to cut power to the load if we ever need to do any work on the system. But you’re right, it would be a bad idea to cut this switch without first disconnecting the solar panels. Whenever we do this, we either disconnect the positive solar panel wire from the charge controller, or pull the fuse from the solar panels, so that there’s no current going through to the charge controller. I could see it being a good idea to also add a kill switch between the solar and the charge controller to make this a bit easier. Hope this helps!

      ~John

    • Hi Matt,

      The easiest way to mount these dimmer switches would in a thin material, like a plastic outlet cover (one without any holes, etc., pre-drilled). The dimmer consists of a post that rotates (which is the actual switch), and the plastic knob that you turn sits on top of the post. Basically, the knob pops off the front, then there’s a little nut you need to unscrew. At that point you’re just left with the post. Drill a hole through the outlet cover for the post to go through, then once it’s through screw the nut back on to secure the dimmer to the outlet cover, then push the plastic knob back on the post. From there, you can mount the outlet cover wherever you choose to put it.

      We made our own cover out of 1/4″ plywood. Since this is a thicker material, we had to do a little customizing and finagling to make it work. Thinner material would be a whole lot easier. Hope this helps!

      ~John

  • Omg! I love your ideas. All of it! Your DIY ideas are awesome. It makes me want to make my own too. Thanks for this creative and awesome DIY ideas!

  • Thank you. What else to say? Can we donate to you cause – for this is a highly praised resource.
    But, I am curious and I can’t quite find a source that clearly states – the charge controller holds the + – solar cables, + – battery, but what did you choose to wire into the + – “Load” slots on your controller?
    I’m a little confused on which appliance has priority for that slot, or is it acceptable to leave it empty – if you’d even want to?
    Thanks again.
    Cheers,

    MK

    • Hi Matt, thanks for the kind words! We work hard to put together useful guides for other vandwellers, so feedback like this means a lot! If you wish, you can support us by purchasing items through our Amazon links (we get a small percentage of anything you buy within 24 hours after clicking one of our links) or you can donate directly to us via Paypal here.

      As to your question – you want ALL of your load items (lights, fan, outlets, whatever else) running into the +/- load slots on the charge controller. Basically, you attach all the positive wires to a blade fuse box, and all the negative wires into a common bus bar (you can also buy fuse boxes with both positive and negative built in like this one by Blue Sea Systems). You then connect the fuse box to the + load slot on the charge controller, and the negative bus to the – slot.

      The only exception to this is the inverter, which you wire directly to the battery.

      Hope this helps! Let me know if I can clarify further, and we’ll look into updating this post in the future to make this clearer.

      ~John

  • I have a 1975 Ford Econoline 350 with 85k miles and 5 on a rebuild. I’m at the point where I’ve wire all my 110 for regular inlet and a shore power hookup. How much did you spend on all the solar panels and 12v wiring and plug ins extra?

    • Hi Zach, here’s a quick breakdown of what we spent on electrical:

      • 400-watt Renogy Solar Panel Kit (includes charge controller and wiring): $800
      • (2) VMAX 155-ah batteries: $650
      • Xantrex 1000-watt Inverter: $250
      • Lights and Dimmers: $120
      • Remote Displays for Inverter and Charge Controller: $50
      • Misc wiring, connectors, fuses, outlets, switches, etc.: $130
      • Total: About $2,000. If you’re talking purely about the solar, the Renogy kits come with the panels and all the wiring you need to hook up to a set of batteries. We have a fairly large 400-watt system, but they have kits as small as 100-watts.

        Hope that helps!

        ~John

  • Hey John, thanks for this fantastic guide. Seriously, you do an amazing job of explaining how you connected the whole system simply but with enough detail to really understand what is going on. Also, your diagram or the system is super helpful. One question, in other places on your site you mention installing a battery isolater and I didn’t notice anything about in the above article. I am a new van owner and am getting ready to build mine out with a set up very similar to yours but I want an isolater so the batteries will charge from the alternator! If you have any tips or advice on how to add an alternator in this system I would greatly appreciate! Thanks for all your amazing guides!

    • Hi Cody, thanks for the kind words! We added our battery isolator after we initially wrote this article, so we actually wrote a different article about installing it that you can find here. Hope that helps!

      ~John

  • This is the BEST explanation of a DIY electrical system I’ve seen so far! Thanks for the great advice! I was wondering… roughly, how much did you spend on your system all together? Including the solar panel kit, batteries, and all the additional parts and wiring needed to complete this part of your van?

    • Thanks for the kind words Deeana, we hope you find our site helpful! We spent right around $2,000 on everything initially, which includes a 400-watt kit, two 155-ah batteries, a 1000-watt inverter, as well as wiring, fuses, switches, lights, etc. Later on we added a smart battery isolator, which was another $115 or so. You can definitely go smaller than we did – depending on your electrical needs you could spend as little as $1,000 on a DIY system. If you’re just starting out / are on a tight budget, we recommend starting with a battery, battery isolator, and inverter, then adding on solar later. Hope that helps!

      ~John

  • Hey John, this is a great diagram. I’m a little lost on what size of wire you used going from the control panel to the batteries and the fuse block. I know you said 4 gauge but looking at the controller, it can only take up to an 8 gauge.

    • Hi Shane, sorry that’s a little confusing! We used the leftover 8 gauge wire from the solar panels to connect to the fuseblock/negative bus, and to the cutoff switch between the controller and the batteries (should be on the diagram). For the rest of the wiring we bought 4 gauge wire that already had ring terminals on each end to finish out the rest of the wiring. You could probably save a bit of money buying bulk wiring and crimping on ring terminals yourself, but at the time we wanted the extra security of using “factory crimps” as much as possible. Hope that helps!

      ~John

      • John,

        First, thank you for the information! It has been invaluable. I’m trying to follow your work and I’m confused about a couple of parts:
        1) As Shane mentioned, I’m confused about you using 4ga cable from the charge controller to the battery. That seems like a very thick cable to use and not supported by my charge controller. I’m was planning on using 10 ga (as I’m using a 30 amp charge controller over a very short distance).
        2) In your schematic, you have a fuse on the negative cable from the solar panels. I would think it would be on the positive.

        Any help you could offer on these matters would be greatly appreciated!

        Darren

        • Hi Darren, I’m glad our guide is helpful! Let me clear a couple things up:

          1) We actually have the 8 AWG wire that came with our Renogy kit plugged directly into the charge controller. On the negative side, this goes directly to the battery. On the positive side, this runs to our kill switch/fuse, where it then transitions to 4 AWG wire that we purchased on Amazon. I will update the post to clarify this when I get a chance. 8 or 10 AWG is probably fine, just make sure whatever gauge you’re using can handle the current output.

          2) This was an error on my part, which should now be correct. Thanks for pointing this out!

          I hope that helps! Good luck with your build!

          ~John

  • Your guide is awesome! Just one question though. If I install all four panels, do I use a 40A fuse from the solar panels to the contoller, as well as on the positive from the battery to the controller?

    • Hi Shane, glad the guide is helpful! Renogy recommends adding a fuse between your solar panels and the charge controller. Based on my understanding of the equation in Renogy’s documentation, a 40A fuse would be a good choice for four panels. Hope that helps!

      ~John

  • Hi John.
    Not sure if you saw my question on how well your 2 12 volt batteries are doing and any issues?
    Also sent you a little donation for your time.

    • Hey Wally, I must have missed your follow up comment, my apologies! We have no complaints with our batteries so far. I really like the fact that they’re sealed, which makes me much more comfortable having them in our living space. We’re also very cautious about how deep we discharge them, but we’ve rarely had to worry too much about it.

      I hope that answers your question! And thank you so much for the donation, it is very much appreciated and helps us keep the site going! Best of luck, and let me know if we can help any further!

      ~John

  • First of all, thank you so much for taking the time to put this website together, I cannot imagine the amount of time that this must have taken and this is so helpful to many of us!!!
    I have a question regarding the wiring of the lights. The ceiling lights have 22 AWG wires and the wires that are running from my switch to my lights is 14 AWG. I am wondering how to connect the two together. All the heat-and-shrink connectors I looked at are not meant for two wires with such different gauges. What size wire did you guys use? And what did you use to connect the two different wires? Thanks!!!!

    • Hi Marlene, so glad you find our site helpful! Our goal is to go into all the questions we had when we started our van build journey, and we love being a resource for other vanlifers as much as we can!

      Wiring size was definitely confusing for us when we were putting everything together. Our lights have 22 AWG as well. Running from the lights down to the switch, we picked up what is basically speaker wire from Home Depot that has two wires (+ and -) wrapped together, which helps simplify installation. I think the wire size is 18 AWG. You shouldn’t need thicker than that for the lights, and that would allow you to use 18-22 butt connectors (the red ones) to join the wires together. Another option for connecting your wires is using wire nuts (which is what we used). However, wire nuts are not intended for the vibration-heavy environment of a moving vehicle, so if you go that route make sure to reinforce with electrical tape so the wire nuts don’t untwist.

      You definitely want thicker wire like 14 AWG or 16 AWG connecting your switches and outlets to your fuse box, but with the lights you should be able to go thinner.

      Hope that answers your question, let me know if I can clarify further!

      ~John

      • hank you so much for replying so quickly John! There are definitely a lot of questions out there, and really I cannot thank you enough!!! 🙂

        I think going with the 18 AWG cable is a good idea. Whatever way I am thinking of wiring up the lights, it seems like I cannot avoid having three cables joining, do the connectors that you are talking about will work for 2 18 AWG cables and one 14 AWG? I am actually thinking of getting a few three-way connectors instead.

        • If you can find a good three way crimp connector that would definitely work! We used wire nuts to connect 5 separate wires together (4 from the lights and 1 from the switch) and it worked out fine for us. We just made sure we twisted all the wires together first, then twisted on the wire nut, then wrapped the wires with electrical tape just below the nut to help take pressure off the connection. Wire nuts are not designed for vehicle use, but we haven’t had any issues with this method, and we thought it was the easiest way to connect that many wires. However, some sort of crimp connector or a common terminal would definitely be preferable.

    • Hi Wally, we actually didn’t dig too deeply into 6V vs 12V when we were designing our system. We zeroed in on AGM batteries pretty early (vs. flooded lead acid batteries) due to them being sealed and safe for indoors without venting. Most of the AGM batteries we were finding were 12V, and we just figured that we’re doing a 12V system, why not get 12V batteries?

      There’s definitely a debate between 12V and 6V batteries, and 6V does have some advantages. 6V golf cart batteries are inexpensive and widely available (though you’ll typically find flooded lead acid instead of AGM). 6V batteries also have ticker lead plates, which can make them last longer and charge/discharge better than 12V batteries.

      I was curious about the cost/size difference, so I ran a quick comparison. Here’s a breakdown of 12V AGMs vs 6V AGMs:

      (2) 125ah 12V VMAX AGM Batteries (250ah total):
      Cost: $599.98
      Size: 13.6″ w x 12.9″ d x 8.7″ h

      (2) 225ah 6V VMAX AGM Batteries (225ah total):
      Cost: $559.98
      Size: 9.5″ w x 14.6″ d x 11″ h

      In this example, the cost and size are fairly similar (though you do get slightly more ah with the 12V batteries). 6V batteries are definitely worth considering, and sometimes the choice can come down to the dimensions you can accomodate in your van.

      Hope that helps!

      Thanks,
      John

  • Hi John.

    Finally I found a site after months of searching that makes since and in detail with photos and clear instructions.
    Very awesome!
    Thanks for taking time out of your schedule to post this.
    I am converting a cargo v-nose trailer into a camper and will keep you posted on my progress.
    Cheers, Wally

    • Hi Wally, glad we can be of help! Best of luck with your conversion, and let us know if you have any questions!

      ~John

  • I love this post! I’m a complete newbie when it comes to electric, and that’s been stressing me a bit about my upcoming build. I’m just going to do everything you’ve done here – easy peasy!

    I was making my Amazon list from your links, and I think some of them have got mixed up! The first link is a Renolgy 400 watt kit, but it links to a 50 watt. And next are the two 155ah batteries, but the link goes to a Y branch adaptor. Am I mixed up?

    • Hi Jasmine, sorry for the mixup! Everything seemed ok on this end. Are you by chance located in Canada or the UK? Our product links automatically redirect from Amazon US to Amazon UK/CA based on location, and things can get mixed up occasionally. Either way I’ll do some digging and try to figure out what’s going on. Thanks for letting us know!

      ~John

  • Hi John,

    I’m about to pull the trigger on solar for my own van build. I really appreciate the detailed product list and write-up. It’s exactly what I am looking for given my lack of knowledge on the topic. Would you do anything different in retrospect?

    Jason

    • Hi Jason, I’m glad you found this post helpful!

      As far as what we’d do differently, I often go back and forth on our capacity. We have a bigger system than most people we’ve met on the road (we’ve rarely met anyone with more than 200 watts), which at first made me question whether we bought too much. But unlike many of our road friends, we never have to worry about looking for somewhere to plug in, and we rarely have to worry about our batteries dipping too low. A system as big as ours is not strictly necessary depending on budget, but it gives us a whole lot of flexibility that’s really nice to have.

      From a more mechanical standpoint, I would install some sort of roof rack and attach the solar panels to that instead of mounting them straight to the roof. All in all, our system works great and we haven’t had any problems. I hope that answers your question!

      ~John

  • I am thinking about installing the Renogy 200 watt solar kit on my teardrop trailer, it is a Runnerway camper. Do I ground the battery underneath the camper’s metal frame like a vehicle’s frame mentioned in your article?

    • Hi George, thanks for reaching out! We love our Renogy kit and can’t recommend it highly enough. The negative ground point in a vehicle is the frame/chassis, so for a trailer it would likely be the metal frame. The idea is to have a common grounding point for all your electrical in order to complete the circuit, and the metal frame seems to me like it would be the best spot. Quick disclaimer that I am not an electrician, and this is my opinion based on my own knowledge and experience. I hope that helps, and let me know if you have any other questions!

      Thanks,
      John

  • Dude, this is beautiful work, the simplicity of your explanation makes all the difference, your electrical diagrams are awesome, I really enjoyed reading the whole article, thanks so much for sharing.

  • Thanks for the post. Amazing write up and descriptions. Exactly what I was looking for to start wrapping my head around this?
    Question for ya, as I am having trouble finding any info out there. You’ve wired directly to the controller, your lights, fan and outlets, I assume the lights and fan you purchased run directly on 12V DC current I thought regular lights needs AC, and I assume the outlets are for 12VDC appliances, like a refrigerator or appliances specific to RV’s?
    And I also assume the inverter would be for your laptop and iphone charging?
    Just trying to understand which is used for what?
    Thanks so much.

    • Hi Paul, the lights we have are 12V DC LED lights, and our fan and fridge also run on 12V DC. The outlets we have are a combination of 12V cigarette lighter outlets and 12V USB outlets, which we use to charge our phones and run our DC appliances. All of this is wired into a fuse block that connects directly to the charge controller. We only really use the inverter for laptop charging, our hand blender, and the occasional power tool.

      Hope that helps and let me know if you have more questions!

      ~John

  • You installed an inverter, but I did not see any 110v outlets in your instructions. Isn’t that what an inverter is for, to change dc to ac? What did I miss?

    • Hi Tom, thanks for reading! You’re correct, the inverter converts 12V DC to 110V AC. Most inverters, ours included, have 110V outlets on the unit itself, so there isn’t additional wiring needed. We do, however, run an extension cord to a 3-outlet power strip that we have mounted to the front of our bed frame. We are thinking about wiring the extension cord to a traditional 110V wall outlet over the winter – if we do we’ll be sure to write up instructions for any wiring involved!

  • This is a fantastic post thanks for the detail and diagrams. One question: Do you run your inverter into 120VAC wall sockets in your van or just use an extension cable. Any safety concerns with either of these?

    Another question: This system seems much bigger than I typically see in van conversions. Knowing what you know now, would you have sized the system (solar capacity, battery bank) any differently?

    Thanks again

    • Hi Daniel,

      Thanks for reading, we’re glad you like the post! Right now we just run an extension cord/power strip from the inverter, which we hang on a hook on the front of the bed support frame. It works fine so far, but dealing with an extension cord all the time can sometimes make things a bit disorganized. We originally did it this way because we just wanted to hit the road, and we figured we could always upgrade/change the configuration later. We’ll be back “home” for a couple months this winter to sell our house, and we’ll be doing a few upgrades to the van – so we’ll probably rethink this and install something more permanent like an outlet. As far as safety concerns with our setup, I think the biggest thing is just making sure the inverter is properly grounded and fused, and has plenty of space around it for ventilation. I haven’t looked too thoroughly into what installing an AC outlet entails, so I can’t comment on that, but we’ll definitely write about it on the blog if/when we install one! 🙂

      We definitely do have a larger system than most vans, but I don’t think we would do anything differently. We’ve met plenty of people on the road who get by with smaller systems, but they’re also constantly thinking about their power situation – especially when boondocking in one spot for several days, which mostly cuts out the battery isolator as a charging source. We recently spent a month living/working on a farm with a few other vanlifers, and we were the only van that didn’t need to run an extension cord to the house. Even with our setup, our battery voltage still got down to about 12.0 in the mornings after a few days of rainy/overcast weather, so I don’t think our system is overkill if you want to stay in one place for long periods. For us, it’s worth it knowing we can be fully off-grid and still run a fan and a fridge 24/7 without having to worry too much about it.

      That said, if you’re working with a smaller budget, then I would recommend starting smaller – you can always add to your system later. If you drive frequently enough, a good 125-150ah battery, a smart battery isolator, and an inverter should meet very basic power needs. From there, I would add Renogy’s 200-watt solar kit (with MPPT controller), and add additional panels and batteries as needed. If you have the budget, then installing a bigger system like ours will only make it easier to be fully off-grid, but if you have a smaller budget then start small and add on. I hope this helps!

      Thanks,
      John

  • Fantastic blog post guys! Quick question, did you guys run wiring for lights, speakers, etc. in the walls before putting the walls up? We’ve just finished insulating and are debating holding off on putting our walls up to run the wiring vs. doing the wiring post facto. How did you guys do it?

    • Hi Tim,

      Glad you enjoyed the post! We don’t have any wires running behind our walls, but we did run wiring for the lights before we put the ceiling up. The wires travel from the ceiling over to the passenger side, down through the hollow frame post next to the side doors, ending where we planned to put all of our electrical components. If you plan on having wire runs behind your walls/ceiling, it would probably be easier to do it ahead of time. Hope that helps, let us know if you have any other questions!

      Thanks,
      John

  • Did you ground both your batteries with 1 or 2 cables? In the grounding picture you showed two wires, but I could only see 1 with the shake proof washer. Much appreciated.

    • One of the grounding wires in the photo is for the batteries (1 wire for the batteries) and the other is for the inverter. There isn’t a shakeproof washer on both wires in the photo because we ran out of shakeproof washers that day, but since the van was stationary we hooked it up “for now” and snapped a photo. It definitely has a shakeproof washer on it now!

  • You mention talking to Renogy tech support in your “Designing Our Awesome System…” section before the wiring diagram but you never explained the resolution. From your wording and diagram it seems you may have a “positive ground” charge controller, hence the need for all your auxiliary wiring to be a complete loop back to the controller (as opposed to a negative ground which allows you to power accessories from the positive terminal and then ground to the chassis…as is typical in automotive applications).
    While it would require more wiring, I actually like the idea of grounding all accessory loads back to the battery/controller, it seems more “right” although it may be completely unnecessary. What did Renogy tech support say?

    • Hi Zach, thanks for the comment!

      Renogy was a little difficult to get a straight answer from, but they basically confirmed what we had been thinking about grounding the loads back to the charge controller. It does take more wiring than chassis ground, but the nice thing about it is it’s nice and tidy, and since everything’s in one place you don’t have to worry about hunting down a bad ground connection if something’s not working. Just wire everything to the fuse block/negative bus, then wire those directly to the charge controller and you’re good to go!

    • I’ve got to second Zach’s grounding preference. Boats, for instance have battery grounding separate from onboard metals which may be part of a different bonding connection, for reasons related to electrolysis. For an RV, the chassis does nothing by way of providing a true ground, although it does offer a fast and dirty common for negative wiring, if all circuits and batteries are so connected. It also makes possible voltage differentials between the starter battery circuits and the house battery circuits. While those differences are likely to be small, the associated current flows could have unexpected consequences. If running a little extra black wire avoids the issue, why not?

      • Thanks for the comment Bob! I’m in complete agreement. It also makes it a lot easier to hunt down any problems with your ground connections. We’re dealing with a bad ground on one of our brake lights right now, so I’m going to have to take off some of the wall paneling to find it and fix it. Much simpler to have a common ground area!

    • Hi Lara,

      You’re right, a battery monitor is not in the diagram! We’ll look at updating it soon.

      There are actually a couple of different battery monitor types: remote displays, and dedicated battery monitors. The MT-5 meter that we mention in the post is a remote display, which basically acts as a “screen” for your charge controller. Setting these up is really simple – they come with a data cable that plugs right into a dedicated port on the charge controller. However, we’ve found that much of the data it shows isn’t the most helpful (the state of charge % is woefully inaccurate).

      We’ve since bought a Victron BMV-700 dedicated battery monitor. Dedicated monitors are much more accurate and detailed, but they’re also more expensive and complex to install (they have to be wired directly to the battery). We’re planning on doing a future blog post about battery monitors, going over pros/cons and how to install a dedicated monitor.

      Let me know if you have any other questions!

      Take care,
      John

  • In your diagram there is nothing coming out of the inverter. I thought the purpose of the inverter is so that you can have normal mains power plug socket. If this is the case, where is this shown on the diagram ?

    • Hi Lara,

      Thanks for the comment! The purpose of the inverter is to convert 12V DC power to 110V AC power so that you can plug in things that need a regular three-pronged outlet – which for us is primarily our laptops, and occasionally a power tool. We didn’t include this on the wiring diagram because the inverter has outlets built into it, so that aspect isn’t really part of the wiring. We do have an extension cord running from ours to a more convenient place to have outlets. Perhaps we can update the diagram to make this a little more clear.

      As for mains power hookups, you can buy combination inverter/charger units that would allow you to hook up to mains power/shore power when staying at a campsite with electrical hookups. Ours is just an inverter, however, so we did not reflect this in the wiring diagram.

      I hope this helps. Let us know if you have any other questions!

      Thanks,
      John

  • should I connect my 12v fuse box to my batteries? Does connecting the fuse box to the charge controller allow the go from the solar panels directly to the fusebox? What happens when there is no sun do you lose power to the fuse box?

    • Hi Jabari,

      We actually include a complete wiring diagram in this blog post. If your system is anything like the Renogy system that we have, then everything wires into the charge controller. There are +/- inputs for the solar panels, +/- inputs for the batteries, and +/- inputs for the load (fuse box). The charge controller takes the current from you solar panels (which comes in at around 17-19V) and uses it to properly charge your batteries (usually at 14V or so), but it uses 12V current from the batteries to power your load.

      You certainly can hook up a fusebox directly to your batteries, but running it through the charge controller lets the CC regulate everything (most CC’s have a low-voltage shutoff if your batteries get too low). However, you would not want to hook your solar panels directly to a fusebox because the voltage will be completely different, which could cause problems. If you run everything though your charge controller and batteries, then the batteries will power the system when there’s both sun and no sun – but when there’s sun, your solar panels will add charge to the batteries.

      I hope this helps! Let me know if you have other questions!

      ~John

      • Hey John,

        Great write up, I’ve used it a great deal to assist in my Renogy Solar setup. I have two 100 watt panels, 20 MPPT Charge Controller, 100AH lithium battery and a 300 watt pure sine inverter. I’m curious about wiring the fuse block as referenced above. My fuse block positive and negative run into my charge controller, however I was curious about this and contacted Renogy which said that was correct but to wire the fuse block to the battery too. Can you elaborate a bit more on wiring the fuse block to only the charge controller -VS- wiring the fuse block to charge controller and battery. Renogy suggested the latter but I haven’t herd a detailed explanation of why yet.

        Big Thanks in advance!!

        • Hi Justin, that’s a mystery to me, and I’ve never seen a system with the fuse block wired to both the charge controller and the batteries. It seems to me like that would be redundant, and I’m not sure what you really gain there (in fact, you could lose out on some features of the charge controller). Running it through the charge controller allows you to get a read out on the charge controller as to the current draw and your usage, and you can cut power to the load through the charge controller. If you also wired it to the battery, I would imagine you would lose out on that data, and would also lose the ability to cut the load feed via the charge controller. You can wire your fuse block to your batteries, or you can wire it through your charge controller, but I don’t see the purpose of doing both at once.

          ~John

          • Yea, I didn’t understand why the tech suggested it but I agree, seems redundant. I’ll stick with only wiring to the charge controller.

            I’ve read through the comments and seen where the LEDs have been mentioned before but I’m still confused, most likely because I seen another wiring diagram where the LEDs are run in parallel, red wire of the LEDs connect to red wire of basic switch, then a separate red wire comes off the same switch runs to the positive terminal of the fuse block. The black wire from the lights connects to the negative terminal of the fuse block. In this diagram it’s not a dimmer switch.

            I’m running the same pod LEDs in parallel but using a Lutron Skylark CL dimmer switch, it has a green wire (ground), Red, black and red with a white strip (traveller wire?). I’m curious if I can apply the same method mentioned above or if I need to apply your method?

            Thanks for the quick response, I’m right in the middle of finishing my van build.

            • Hey John, I figured it out! My Lights are wired in parallel, which gives me a single black and red wire from the lights. I attach the black wire from said lights to the negative side of the fuse block. Then I attached the single red wire to the red wire of the dimmer switch. Then I attached the black wire from the dimmer switch to another black wire and ran it to the positive side of the fuse block. I attached the green wire from the dimmer switch to a black wire and ran that to the negative side of the fuse block. I capped the red wire with a white strip (traveler wire) on the dimmer switch. Woot Woot, they work!
              I really appreciate all the write ups, you’ve helped another van get on the road.