Alright, time to get stuck in to the electrical! Unlike the carpentry, I felt a little more at home when it comes to the electrical side of the build since this is an area I have delved in before and I really enjoy pulling components apart and seeing whats going on inside. That said, my adventures into this world have never taken me into vehicle electrics so this was something entirely new for me, which made it even better!
Like any project, having a good plan of attack before you dive into the guts of it is vital if you want to make the installation as smooth and as hassle-free as possible. This is especially important when it comes to pulling the cables, but more on that later. Let’s go through each planning step one-by-one.
Step 1 – Plan and design your circuit
If you are like me and have a hard time visualising the design of the circuit in your head, then you are going to want to get yourself in front of a mouse and keyboard (or pen and paper) and sketch up a the full circuit. Even if you do have a good idea of how it is all going to look without putting it on paper, it goes a long way to have something to refer to later if you need to troubleshoot some problem months or years down the track. I did a rough sketch with pen and paper and then used draw.io to create the final design.
I do not need to reinvent the wheel and talk about how these cables and fuses were sized up. Instead I will point you to this video by Greg Virgoe who explains it all better than anyone. Right now you don’t need to worry about sizing up the blade fuses for the appliances, but you do need to account for all the 12v appliances in your van so that you know what size blade fuse box you need to purchase and you do need to size up your cables so that you purchase the correct diameter conductor. The fuses between the split charge relay are standard 100 amp strip fuses that came with the split charge relay kit, which I will talk about further down. I highly recommend giving yourself some wiggle room when purchasing the blade fuse box. If you have six appliances and install a six-way blade fuse box then you will not be able to install any extra appliances in the future without having to replace the blade fuse box first. I recommend investing a few extra coins and get yourself a fuse box with at least one or two spare feeds.
In Greg’s video linked above he also talks about different types of cables and how to choose the appropriate conductor size, so be sure to watch it so you know how to properly size up your cables.
Step 2 – Sizing up your power source
In your van the power source is your leisure batteries and it is important to ensure you pick the right type of battery with enough capacity to provide power to your appliances and devices for the desired amount of time. When it comes to sizing up the battery, Greg Virgoe provides all the information you need in this video, and as a bonus he talks about sizing up for solar, if that floats your boat (or van ;))
There are a few different types of 12v batteries on the market, ranging from your cheap flooded lead-acid battery to the expensive lithium-ion battery. The main factor here is price and after you do a little bit of research it is quite clear that lithium-ion is by far the superior choice, but you are certainly going to pay for it. I will not go into details on each battery type here since there is a wealth of good information out there already, but I will say do not use flooded lead-acid batteries in your camper van. They pose significant health risks and should not be used in enclosed spaces (see 2.3.1).
The general consensus in the van life community is to use AGM batteries for the most bang for your buck, but if you are willing to throw a bit more money at your build then by all means go for lithium-ion. They are not only more efficient and have more usable energy, they are also much lighter and every kilogram counts when it comes to van conversions. This article, whilst a little old, provides a really good comparison between AGM and lithium-ion batteries.
Step 3 – Locations and cable measurements
At this stage in your build you should already have a pretty good idea of where your appliances are going to be located. What you may not have figured out is how you are going to get the cables from the power source to the load (the appliance). The location of the power source is also a deciding factor in how your cabling will be run. Most builds have the power source located at the rear or middle of the van up against one of the side walls. At a minimum you will need to take into account space for the batteries, fuses/circuit breakers, blade fuse box, and cabling. It is however very likely that you will also have things like a 230v inverter, solar charge controller etc, so make sure you have plenty of space for extras. Since you may need to do some troubleshooting from time to time you want to make sure all of this is easily accessible. A common location is under a bench or bed with a hinged lid. At the same time keep in mind that you will also need to ground the negative terminal of the battery to clean section of the vehicle chassis that has been sanded down to expose the aluminium underneath.
Once you know the location you can then figure out the best path to take your cables from the source to the load. This will usually be through the walls and ceiling of the van, but in some cases the most direct path is along the floor, which you can run at the same time you install your flooring. Most people will guesstimate how much cabling they require, but if you are on a tight budget or you just want to be really precise with your requirements then you can use some string to run from the source to each load and then take a measurement of the string.
Step 4 – How to charge your power source
Now obviously your leisure battery isn’t going to last forever on a single charge, so you need some way to recharge it. Solar is one popular choice amongst the van life community, the other is a voltage sensitive relay (or split charge relay) which you will see referenced in our circuit design diagram linked above. Whilst we do plan to install solar on our van eventually, right now we opted to just go with the VSR kit to keep the initial build cost down. If you are not familiar with VSR’s and how they work, see this video for a good overview. In short, a VSR allows you to connect your vehicle’s starter battery to your leisure batteries and will charge them while the car is running, without having to worry about the start battery ever getting drained by the leisure battery. There are a few VSR kits available for purchase which come with everything you need, including the 16mm cables. We chose this one here.
Another way to charge your leisure batteries is a 230v hookup point with a transformer down to 12v. Since we plan to mostly free-camp we will not be implementing this into our build, but there are many other blogs and videos out there that detail how to do this.
And that’s about it for the planning! Stay tuned for part two where we get stuck into the grunt work and start pulling some cables!