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Avoid These 5 Mistakes When Building Your Own Van

A van with wheels on fire

Building your own van is an exhilarating adventure for fellow van-lifers and road warriors like you! The freedom of the open road, waking up in new places every morning – it truly is a unique experience. But, let’s face it, the journey to a perfect van build can be as bumpy as a backcountry trail.

From wire crimping mishaps to running out of supplies halfway through, we’ve all been there. That’s why we’re here to talk about some common slip-ups in the van building process. Consider this post your friendly trail guide to avoiding electrical mishaps, insulation woes, and other mistakes new vanlifers often make.

In this post, we’ll cover five crucial mistakes to steer clear of while building your own van we made! From mismatched terminal sizes to underestimating wire needs, and even positioning solar panels incorrectly, we’ve got you covered. So, let’s jump right in and make sure you avoid these pitfalls!

Grab a cup of joe, settle into your swivel chair, and let’s explore these valuable lessons learned from the road. Just like a challenging climb or a tricky hiking trail, building your dream van is all about learning, adapting, and enjoying the ride.

Before we begin, be sure to check out our article on all you need to know about vanlife, where we discuss the good, the bad, and the ugly of living in a van full-time.

Now, let’s get started!

This post includes affiliate links, but rest assured that we only recommend items we would use ourselves. And if you choose to make a purchase, we receive a small commission. No sponsorships, just the truth about our favorite finds.

Mistake #1 – Not Matching Terminal Sizes

I feel I need to put a disclaimer right from the start. When we got into our van build, we knew nothing about anything. We had no carpenter, electrical, or engineering experience.

Some mistake are not as bad while building your own van.

We relied on youtube, google, my dad, and the grace of the gods to get us through this build!

That said, we’ve learned a TON, and we hope this article can help first-time van builders. We really wish we’d had something like this when starting out!

So, if you also know nothing about anything, we’re here to help!

Our first mistake was not matching the terminal sizes for our lugs. Lugs come in all different shapes and sizes, from ring terminals to spade connectors. If you aren’t in the electrical industry, this can be confusing.

Let’s break down how to match your lug to your terminal to ensure you have the perfect connection.

Matching The Lug To The Terminal

Lugs and terminals

M6 connector, M8 connector – what are all these different sizes?? To start, the ‘M’ stands for metric. The number after the M correlates with the measurement in millimeters. So, M6 = 6mm lug size, which is about 1/4 inch.

Here’s a handy table that lists the lug size and the associated metric measurement. I’ve also included the close equivalent in inches:

Lug SizeMetric MeasurementInch Measurement
M66mm~0.24 inches
M88mm~0.31 inches
M1010mm~0.39 inches
M1212mm~0.47 inches
M1414mm~0.55 inches
M1616mm~0.63 inches

Everyone’s electrical system is set up differently, but eventually, you have to connect your wires to something. This is where we made our first mistake. We had no idea that there were different terminal sizes on lugs!

Maybe this is common knowledge for most, but for newbies like us, we had no clue!

We bought a bunch of M8 lugs (3/8″) when we really needed M6 (1/4″). The 3/8″ worked on the 1/4″ terminals, but the connection wasn’t very secure, and we had to add a larger washer to create a stable connection.

As soon as we figured this out, we started matching our terminal sizes to our lug sizes, and everything fit tighter, which helped make a better connection for the electrical current.

This mistake wasn’t a huge deal, as we made it work, but it’s certainly something we wish we had known from the start!

How To Measure Your Terminal To Match Your Lugs

Whether you’re connecting your wire to a bus bar, a circuit breaker, or the fuse box, you will need something to connect the wire to the terminal.

This is where lugs come in! Once you match your lug to your wire size, it’s time to figure out how big the terminal needs to be.

To figure this out, measure the size of your terminal (what you will connect the lug to – this will typically look like the bottom of a screw). Bust out a tape measurer and measure the span of the terminal. Since it’s a circle, you can measure from anywhere.

Most terminals will be precise numbers that will match a lug size. For example, it might be 1/4″ or 3/8″, which you can match to the lug size.

For example, if you’re using a 10-AWG wire and measure your terminal to be 1/4″, you’ll need a 10-AWG 1/4″ lug! Simple, right?

Now, let’s move on to wiring your van!

Crimping a wire to connect it to the electrical system to avoid a van build mistakes

Mistake #2 – Buying Too Little Wire

For our van build, we bought a Ram Promaster 2500 High Roof. We got the 14-footer which we thought would give us plenty of room without feeling like driving a boat.

When we started wiring, we bought two 100-foot rolls of 14-AWG wire. One red, one black. We thought this would be PLENTY for all of our appliances. After all, we only had two sets of 6 lights, two switches, five charging ports, a fridge, a fan, and a toilet. And it’s such a small space, right?

We quickly went through the 100-foot rolls and bought 50-footers, thinking we’d never go through them. Then we purchased two more 100-foot rolls and barely made it with those!

The point is, your van is a lot bigger than you think! You put some mileage in when you start running wires all over the roof and walls.

If we could go back, we would buy two 500-foot rolls (one red, one black) and be done with it. Not only would it have been more convenient, but we would have saved a lot of money by buying in bulk.

For the larger wires required for the house batteries, solar, and DC-DC charger, we measured carefully and got them cut by the foot, which worked perfectly. However, buying in bulk would have been better for the smaller wire.

Having a basic outline of all your electrical components before you start your van build is an excellent way to avoid issues like this. We have a great informational article on the things to know before you start vanlife, where we discuss learning your electrical system before you start your build.

Mistake #3 – Buying Incorrect Size Circuit Breakers

Circuit breakers and wire size were two huge unknowns for us going into this build. We had no idea the difference between 6-awg and 12-awg wire. We didn’t know the difference between watts and amps. Basically, we knew nothing.

We soon learned about wire sizes and how to pair them with our different electrical equipment. But something we really didn’t understand was the circuit breaker sizes. And it didn’t seem like any Google searches or forums had the answer!

So, we went to a specialist! A friend of a friend of a family member was generous enough to let us bring our van to him and have him check out our electrical setup. He gave us some vital information, which we’ll share below!

Sizing Circuit Breakers To The Fuse Box

Your circuit breaker should closely match the amount of amps pulled through the wire. It should not necessarily match the wire size, especially since you can size up in wire without increasing your amps.

For example, all our appliances will never pull more than 35 amps. So, between our house batteries and our fuse box, we have 50-amp circuit breakers. However, we use a 6-awg wire between the batteries and the fuse box, rated up to 60 amps. So, we didn’t size our circuit breaker based on the wire size but instead on how many amps will be pulled if everything runs simultaneously.

A good rule of thumb is to buy a breaker equal to 125% of the max amps. So, 125% of 35 amps is 43.75. From there, round up to the next size, which would be 50. Learn more about it here!

Sizing Circuit Breakers For MPPT Controllers and DC-DC Chargers

Now, for the circuit breakers between chargers and controllers, it’s a little different. We bought a 40 amp MPPT charge controller for our solar panels and a 40 amp DC-DC Charger for the van batteries.

For these, we went with what the manuals told us, which was a 50-amp breaker for both. This will depend on how far your controllers are from the panels and batteries, so instead of sizing your breakers for the amps, size them according to the recommendations in the manual.

You can also contact the company where you bought them from and ask for guidance on sizing the circuit breakers and wires between these items. We went with Renogy for all our solar equipment, and their customer service answers pretty quickly about inquiries, usually within a day or two.

Mistake #4 – Not Painting Boards Before Installing

The walls or cabinets will cover many boards you put up at the beginning of your build, so you may not think you need to paint them.

We found out later in our van build that we should have painted everything. A few nooks and crannies show through even after you put up the walls and cabinets.

We had to go back and paint things after the cabinets were up, which was a pain. Once you choose the color for your van, paint everything before you put it up. Even if it’s getting covered up, it helps the van have a finished look once everything is complete, especially around those corners and weird-angled areas that are tough to cover.

Mistake #5 – Putting The Solar Panels Too Far Forward

Solar panels on a van

Choosing how you attach your solar panels to the roof is as varied between vans as hairstyles are between people. Some choose to use roof racks, and others drill directly into the ceiling of their van.

Whatever you decide to do, consider the wind resistance of your van and the associated gas mileage.

We attached our solar panels to a roof rack from Fiamma. We used all-thread and welded them into J-hooks and U-hooks to attach the panels to the frame. Unfortunately, we attached the solar panels at the front of the roof rack, slightly over the front edge.

It looked great and gave us plenty of room to add to our solar system if we wanted or to put other things on our roof (which we ended up putting our boulder pads up there!).

The downside is that our solar panels now catch the wind as we drive and lower our gas mileage because they increase our wind resistance. We could move them back, but we decided to leave them as they were because adjusting the J- and U-hooks was so tricky.

If we could go back, we would attach our solar panels further back for a more sleek design. Or, we would have opted for a low-profile roof rack instead of the higher-profile one we purchased.

Building Your Own Van, Happy Little Mistakes

So, there you have it. Five happy little mistakes we made while building our van. We had so much fun figuring out our van build, and we learned an incredible amount of knowledge about our electrical system and some carpentry skills!

Overall, we would have changed only a few things if we could go back and do it over again. The five mistakes discussed here were some of the more annoying things that would have made the build easier but never jeopardized any equipment or the overall finish of the van.

Having a celebration drink after completing the van build.

We hope this article helps you in your future or current van build! For more information about vanlife, check out the Dirtbags With Furbags blog!



  1. So much for the “hippy days” where you just threw the mattress in the back of a van and headed out. LOL

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