Van Build | Electrical

This may be the most daunting part of any van build. Even for me and I’m an electrician… Alright, I’ll admit, not a very good one.

You will have loads of questions.

What type and size of battery? How do I charge the battery? Do I need solar? What wiring do I need? How do I fuse everything? How do I connect wiring? Can someone please do this for me?

After googling these questions, you will probably still be as confused as before. Nevertheless, don’t let that stop you.

In my opinion, the best way to figure this out is to break it down into sections and work through them one at a time. Remember, experience is usually the best source. So ask friends or family who are more familiar with electrical work. And by all means, ask me!

I could babble on about Specs for ages, but that is not the point of this blog. Hopefully, I can supply enough info to help you make the correct decisions, without putting you to sleep.

Please remember, electricity is not a game and can be very dangerous. The last thing you need is an electric shock or fire starting. So be sure to follow manuals and ask the appropriate people before proceeding with electrical work.

Now all the doom and gloom is out of the way, let’s begin!

Battery Types

Let’s start with your batteries. Don’t think you can just throw an old car battery in and bobs your uncle. I mean, it will work but not for very long. The desired battery will be a form of deep cycle as these batteries are designed to be discharged and recharged many times, providing a steady output. There are several options available such as flooded, Gel, Lithium, and the most common AGM.

  • Flooded (not recommended)

This is basically lead-acid in a non-sealed container. Also, they need to be stored upright in a ventilated area, as hydrogen gas is produced when overcharging occurs. Another requirement is you must top them up with distilled water every so often. Yes, these are the cheapest option, however, I would not recommend to my worst enemy.

  • AGM (recommended)

Probably the most sought-after battery on the market for this specific use, in fact nearly every build we researched used this style of battery. Some of the pros; a sealed casing, can be stored in any position, is easy to charge, has a high power capacity and most importantly it’s safe to use in limited ventilation. For these reasons expect a higher price tag when compared to a flooded type. But the price comes in lower than the next two types below.

  • Gel

Gel-type batteries have very much the same traits as an AGM battery. However, they are more expensive, don’t have as high power capacity, and must be charged correctly to ensure the life of the battery. In comparison, I think the AGM takes the cake.

  • Lithium

While Lithium batteries are still a relatively new technology, they appear to be a solid choice for your van… if your budget allows it. We aren’t talking hundreds here, we are talking thousands for this so-called bee’s knees of batteries. I’m guessing this is out of nearly everyone’s budget, but let’s talk about them anyway. We already know they are pricey but this means they come with some very positive attributes. For instance, a high energy density (meaning a smaller battery can provide the same power compared with the other types) and a very low self-discharge rate. The choice is yours, just keep in mind there are better things to spend money on…

Battery Sizing

Battery sizes are measured in Ah (Amp-hours) To figure out your sizing, all you need is a rough idea of the amps (electric current) you will use and how long you intend on going without charging.

You should be able to find these (amp) ratings in product descriptions and these ratings are measured per hour. To figure out how much electricity you will use, first you must decide on how long you intend on using said appliance every day.

Yes, bring back the days of high school maths. Who would have ever thought you would need that again?

Here is a basic example of amps used in a day:

  • Lights – 2 amps x 4 hours of the day = 8Ah
  • Fridge – 2 amps x 24 hours of the day = 48Ah
  • Chargers – 3 amps x 4 hours of the day = 12Ah

Total = 68Ah per day

As always, nothing is ever easy. Deep cycle batteries don’t like being fully discharged. Essentially, the more depleted a battery gets, the less life you can expect. Taking this into consideration, you should follow one simple rule – ‘never drain the battery below 50%’. Unless unavoidable of course.

For instance, you may think 80Ah is more than enough to handle the above example. However, depleting the battery by 90% will cause drastic long-term effects if done repeatedly. In fact, it will reduce the battery life by 10 fold. In light of this, a 140Ah battery would be a much better choice.

Once you have your rough daily electricity usage, the next step is to decide how many days you intend on going without charging said batteries. Obviously the longer you intend, the bigger the battery bank will need to be. Using the above example again, say you want to go 2 full days without charging. All you need to do is double the 68Ah, giving you a total of 136Ah. Remembering to add your buffer, you would be looking at around a 260Ah battery bank. This is why selecting the correct charging system is so important. As you can see, the battery sizing would just become ridiculous without it.

Charging Batteries

The next two topics are perhaps the most important part of your electrical system.


First, we will tackle using your vehicle’s starter battery (alternator) as a source for charging. There are several different methods, below are the most common:

  • Battery Isolator

The most basic and cheap form of charging system. Using the simplicity of charging your auxiliary batteries by connecting straight to your van’s alternator. However, you will need to wire it in a way that only allows charging to occur when the vehicle is running. If this is overlooked, the end result will be unwanted discharge of the vehicle’s starter battery, and yep you guessed it… Your vehicle won’t start. For this method, and to correctly wire, you must connect your alternator to your auxiliary batteries via a relay controlled from the ignition switch. If this isn’t making much sense to you, skip down to the next isolator. As I mentioned, these are cheap and will only set you back up to $50.

  • Smart Isolator

Similar to a standard battery isolator but much more simple to install (no relays needed). This is achieved by the smart isolator sensing the voltage and when increased above 13.3V (vehicle started), charging will commence. When the voltage decreases below 12.8V (vehicle turned off) charging ceases. While they are slightly more expensive (between $50 and $200) they’re more user-friendly. I would recommend this as an entry-level charging system.

  • DC to DC Charger (recommended)

Here’s where the price takes a hefty jump, and for good reason. Providing a better charge, this charger prolongs the life of your batteries. In addition, most come with a built-in solar MPPT which allows all charging to be controlled via one common device. These all-in-one chargers can generally handle larger battery banks and are easy to install. Likewise, with the smart isolator, you connect the alternator to your batteries via the DC-DC charger, then it takes over and does all the rest.

Make sure you check the rating of the charger before purchase, as most have a lower output than what your alternator will provide. Hence, the better charging pattern. However, This can lead to extended periods of time required to charge large battery banks. A great bang for your buck charger ($300-$1000), especially if you intend on using solar.

  • Battery management system

Onto the mother of all systems. These are the top of the line in charging. Much like the DC-DC charger, they bring DC and solar charging into one device, with the added bonus of AC. This means you can charge straight from your home power, or plug straight in at a powered campsite. Being the top of the line, you would expect they look good. Most come with a digital display for you to gain access to information on charging state and battery health, along with a bunch of other stuff you probably won’t ever look at.

They are very good but as you can imagine, they are very expensive and probably out of most people’s budget. For example, Redarc (top brand in Australia) provides these systems and the cheapest option comes in at a whopping $2000.

Do I Need Solar?

This question is a broad one and will get different opinions from different people.

In my opinion, yes, solar is a great idea. Not only is having two means of charging smart, but it may also get you out of trouble in more ways than one.

Really, the big decision here is do you go all out and have a permanently mounted system integrated with a more advanced charger? Or do you just keep it simple and go with a portable camping panel?

The choice should come down to how long you plan to spend relying on only solar to charge. If you’re going to live in your van then, by all means, go all out. But if you’re just using it for quick trips, a portable system may be much easier. Not to mention, a lot cheaper!

One thing I will suggest is don’t only rely on solar. Incorporate solar with the DC-DC charger mentioned above.


Do you need an inverter? If you plan on using standard kitchen appliances, you might be in for a rude shock. You may be surprised to learn that a standard kettle will use about 1800 watts to boil. What this means is… don’t worry, I won’t bore you with more maths. All you need to know is a kettle will use around 140 amps on a 12V system! Yes, you read correctly. But what about the toaster, microwave and oh no… not the coffee machine! Unfortunately, all these items are in the same boat. A 2000 watt pure sign wave inverter is needed to meet the power requirements. By the way, if you’re not familiar, this is a big inverter and will be expensive!

If charging devices is all you’re worried about, it is more efficient and to be honest, easier to charge directly from a 12V system. All you need is the correct adapters.

Summing up, unless you can’t deal with instant coffee boiled on a gas cooker, you may want to reconsider. That being said, inverters aren’t out of the question, you will just need to be smart in how much you use these high-power appliances, and certainly take this into consideration when choosing battery size.

Size Of Wiring

This is an important one to get right as using wiring that is too small is a significant safety issue and can result in fires. I definitely recommend using automotive-specific wire, as solid stranded wire (your everyday household wire) may break under the heavy vibration of your vehicle.

The size of the wiring depends on the maximum current and length of the wire run. All of your electrical gear should come with a max load in amps, and this is the value to use for max current (same as the Amps rating we talked about earlier). As for the length of your run, measure the distance from your fuse panel to the appliance location and then double it, as you need to compensate for the return wire as well.

Put these values into a wire size calculator and this will tell you the correct size.

If there are any doubts in your mind, remember, it won’t hurt to choose the next largest size. It might be a bit more expensive but hey, it’s worth your life!


Remember, fuses are intended to be the weak link in a circuit. This means that if there is a fault, you want the fuse to blow as quickly as possible, not the cable. Consequently, your fuse sizing should be less than the rating of the cable, but more than the load of the circuit.

Load < Fuse < Cable.

Here’s an example; say you have a lighting circuit that draws 1A, you would want to use a fuse rated higher than 1A but not ridiculously high, let’s choose a 2A fuse. All you need now is a cable that is rated higher than 2A over the length of your cable run (this is where that cable size calculator will be your best friend).

Now for the parts. Automotive fuse boxes are great to use for your load circuits such as the fridge, lights, and outlets as it keeps everything neat and they are relatively cheap. On the other hand, fusing your batteries requires more heavy-duty gear and if you are in doubt, consult with a battery dealer or someone with more knowledge on the subject. I recommend getting quality gear such as Redarc (in Australia) for this application.

Terminating Cables

Most of your connections will and should be done using either insulated ring terminals or spade connectors. Don’t underestimate the value of using the correct tool, as creating a bad connection is one of the most common causes of a faulty system. The best tool for the job will be a ratchet-style insulated crimper. While these crimpers aren’t part of your standard tool kit, they are cheap and very easy to use. As an added bonus, there are many tutorials you can watch if you get stuck. For larger cables, you’re probably going to struggle without purchasing expensive gear such as a hydraulic crimper, however, this is just impractical and not to mention silly since you will probably never use them again.

A better option would be to figure out how long your cables need to be and buy pre-made ones. You could also ask a battery dealer, as most will make them for you on request.

My Design

Now you have all the gear and somewhat of an idea, Time to get to work!


The first step, run all the wiring. This cannot be stressed enough! The last thing you need is to install the linings and realise you’ve missed a cable, then have to rip your wall off to fix it! So be sure you have thought of everything before moving onto the ceiling and wall installation.

For my power circuit wiring, I used a heavy-duty 2.5mm cable (14AWG) as this is tough and also has two layers of insulation. As for the lights, I used a heavy-duty 1.5mm cable (16AWG).

The actual process of running the cables is very simple:

  • Measure the distance, remembering to double check!
  • Cut to appropriate length, giving yourself some margin for error.
  • Run the cable in a way it won’t get damaged. (If you can’t avoid sharp edges, use something like rubber to cover them)
  • Secure it so it won’t rub under vibration. (Cable ties are your best friend)

I used adhesive cable tie mounts to secure the cables in place and they worked great.

Pro tip: Do one cable at a time and label both ends to avoid confusion when connecting.

Dylan running cables


Next step, installing the batteries and control gear. The space underneath the passenger seat turned out to be perfect… to the millimeter! And was the closest possible point to the starter battery. I didn’t cover the importance of this specifically above, however, don’t underestimate the benefit of making this a priority. As the closer the Auxiliary batteries are to your starter battery, the smaller the cable will need to be and you won’t have high-powered cables running through your living space. After all, the mains cables don’t run under the dining room table in your house, do they? This obviously won’t be possible for every design but if practical, I recommend this method.

I’m sorry, but I’m not going to provide a wiring diagram, as different controllers require different wiring (also I didn’t do one). So to avoid confusion, be sure to follow manuals or seek help if needed. As I will keep saying, ask me if you’re in doubt because this is another thing you need to get right.

I am using two Full River 120Ah batteries connected in parallel to give me a total of 240Ah with a Redarc BCDC1240 charger. I chose this charger as it had the capability to connect solar easily. Turns out, this was a smart idea since we now have a solar blanket that can be plugged in and thrown on the roof when needed. As for the fuses, I bought the appropriate fuse kit through Redarc to match the charger. Here’s where installing the batteries close to the source comes in handy, I was able to use 6AWG wire as the largest gauge and corresponding ring lugs to suit. This is where being an electrician comes in handy, I had the luxury of accessing the appropriate hydraulic crimpers. Just the luck of the draw I guess.

To begin, Start by mounting all of your gear in a neat manner. I mounted mine to some plywood offcuts, which I then bolted to the walls.

Using the manual – yes even an electrician used the manual… told you I wasn’t a good one – connect the wires, making sure to double-check all are very tight. It is also good practice to use heat shrink in order to cover un-insulated lugs as a medium to remove points where you can touch live cables. A decent hair dryer should do the trick to shrink it. If needed, electrical tape can be used as a plan B.

After that, I installed a main Circuit breaker switch. This is so we can isolate (turn off) the power to my circuits when not in use. At the same time, I installed the fuse box and connected all load circuits. Remember, using ring lugs is the best practice. (Don’t install fuses at this point as you don’t want the wires to be live until everything is connected)

Space under passenger seat
Charging gear mounted
Gear mounted and wired up

Now it’s time to put a hold on the remainder of your electrical work and install your ceiling and walls, as all that’s left is to mount and connect your lights, outlets, and switches.


To finish off, I used slimline LED downlights. These were very simple to install and put out more than enough light. Actually, way more than I expected. 8 were installed to keep it neat, however, this was too many. I would suggest 4 maximum, especially if you have a smaller van. To install, I cut the wires quite short and crimped the spade-style lugs onto them. Next, I crimped the lugs onto the other cables, and finally, it was just a matter of plugging them in and screwing to the roof.

Screwing sownlights to roof

I didn’t want to overcomplicate things by running two-way switching and having 10 different connection points. So I went with an automotive switch panel. This panel came with light switches, USB chargers, and a cigarette lighter output. More than enough for such a small place.

Improvisation was needed to mount this panel, as we decided not to install walls in our van. So I made a small wall panel out of white MDF board. (Will delve into this a bit later on)

I do have some extra outlets throughout the van for things like our water pump. However, in a smaller van, this one switch panel is all you should need.

Hopefully, I have helped and this hasn’t just been a bunch of waffle. All jokes aside, I am a qualified electrician with 8 years of experience (just remember… not a very good one), so please don’t hesitate to get in contact if you need extra help!

Equipment used:

  • 2 x 120Ah Full River AGM Batteries
  • Redarc BCDC1240 charger with built in solar MPPT controller
  • Redarc fuse kit
  • 40A circuit breaker
  • Automotive fuse box
  • Industrial orange circular 2.5mm 2C+E flex cable
  • Industrial grey circular 1.5mm 2C flex cable
  • Adhesive cable tie mounts
  • Cable ties
  • Ring lugs (various sizes)
  • Spade style connectors
  • Heat shrink
  • Automotive switch panels
  • Led strip lighting
  • Fairy lights

Tools used:

  • Pliers
  • Side cutters
  • Ratchet insulation crimpers
  • Hydraulic crimpers
  • Various screwdrivers
  • Drill and drill bits
  • Spanners
  • Socket set
  • Electrical tape
  • Heat gun/Hair dryer

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