The complete electrical system in my DIY Ford Transit camper van.

This article was updated on 9/20/20 to reflect my final electrical configuration. The upgrades I made were swapping a Tripplite UPS / Inverter for a Renogy 700w Pure Sine inverter, swapping my two golf cart batteries for BattleBorn lithium iron phosphate batteries, and adding an AiLi battery monitor.

Planning a conversion’s electrical system is rather intimidating, but I’ve found that putting it down on paper helps. The diagram below was made on diagrams.net, but your first step should be writing down a few lists: what needs power? What feeds power? What stores power? From there, you can research power requirements, determine the proper wire gauge, etc.

My system has been in use for over a year, so by now I’ve gotten a pretty good idea of what works and what doesn’t.

I’m going to be listing all of the electrical products in my van that generate, consume, distribute, or store electrical energy. I’ll also provide some insight about each component, to hopefully guide you in your design and execution.

Updated-Electrical

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12v Battery Bank

I upgraded my van to Battleborn batteries when I got tired of watering the golf cart batteries I’d designed it with originally. I’ll expand on this in a later article, but if you can afford it — there’s no better choice. Only drawbacks: price, and charging in freezing temps is problematic. My heater takes care of that. A budget option would be VMax AGM GC2 Deep Cycle batteries (more expensive than flooded, but cheaper than LifePo4). With the VMAX batteries, I’d still get the benefits of golf cart batteries (designed for deep discharge, thicker plates, energy dense), with none of the downside of flooded lead acid (watering, offgassing, leaking acid).

100w Solar Panels

The panels I chose are affordable and have worked out great. I have them wired in series, which the MPPT charge controller can handle just fine. If you want four panels with this controller, you have to do series parallel wiring OR choose the 30 (or 40) amp upgrade model. I found myself wanting to add additional panels, but once I moved to LifePO4 batteries, 200w does a great job keeping them charged, even in less than optimal sunlight.

Solar Charge Controller

I went with this basic controller with a remote display. It’s capable of accepting 20 amps, and the load terminals on it can support 20 amps. As you can see in my diagram, all of my van’s loads are connected to a fuse panel. That fuse panel is connected to this controller, not the battery directly. As a result, I can use the remote display of this controller to see my real-time power usage with no extra monitoring components required.

Battery Monitor

This battery monitor was cheap, but highly effective. My original build (with lead acid batteries), I was able to use voltage as a rough estimate of battery life. With lithium batteries, you need a monitor like this that keeps track of amps in and amps out to truly get an idea of your charge percentage. I wrote an article on this monitor and how to install it here.

Disconnect Switch

The + load terminal on my charge controller runs to this switch, and then continues onto my fuse panel, where all my DC loads get their power. By turning this switch, I disconnect power to all loads connected to the fuse panel. My charge controller, as it turns out, lets you do the same thing by pressing the “OK” button on the remote display. Still, I like the physical switch option.

Inverter

I switched from an older UPS to this pure sine wave inverter in 2020. 700w is plenty for my purposes — the only A/C things I run are my laptop charger, toothbrush charger, and an external hard drive. You should look for DC chargers for as many items as you can, the conversion process through an inverter is inherently inefficient in comparison to something that would plug into an accessory outlet.

Shore Power Connection

This is simply a passthrough for me, I can plug in an extension cable beneath the van, and then connect my power strip / power center (below) to it on the inside. Similar to just running the extension cable in through a door or window. In my original build, I had a shore power charger that utilized this, but I found it unnecessary.

120v AC Receptacle

The inverter / converter (UPS) has two household outlets on the body of the unit. One of those I’ve left open, the other I have this plugged into. This unit is installed next to my bed and provides 2 additional household 120v outlets, as well as two USB charging ports.

Battery to Battery Charger

My wording here is not 100% accurate. This Sterling DC-to-DC charger only allows for connection to the Customer Connection Point when the voltage feeding it goes over a certain threshold. Typically, that’s a level that is only reached when the alternator is producing power. A huge advantage of this unit over a standard battery isolator is that the Sterling delivers clean and proper 4-Stage charging to your house batteries, rather than just allowing your vehicle’s alternator to connect to your house batteries.

12v + Fuse Panel

This fuse panel is where all of the DC loads in my van terminate. Pro-Tip: buy a fuse panel with a few extra slots than you need for unforeseen future expansion! This panel connects to my LOAD terminal on my charge controller, but could also be connected to your battery’s positive terminal. Use the appropriate DC circuit breaker on the supply line, in either case. Also: be sure to select the proper amperage fuses. Never replace a fuse with a higher capacity fuse, the result can be melted wires or worse.

12v – Bus Bar

There’s nothing particularly sexy to say about this. The negative/ground wires from all of my DC loads terminate here, and it connects directly to the negative post of my battery bank.

USB LED Strip

I can’t say enough good things about this little LED light strip. It’s controlled via an app on my phone, includes a little remote control, power draw is minimal, and I can change colors and patterns to suit my mood. Bright white helps when I’m cooking, strobe patterns when I’m showing off my van or listening to some funky tunes (just kidding, it’s always bluegrass), and I often use it on the dimmest setting when I need some light but don’t want to run the overhead puck lights. Powered by USB. Plugs into the 5v USB Step-Down below.

USB Cellular Booster

My van has always-on wifi, which my thermostat, phone, laptop, tablet, Chromecast, and sometimes friends are connected to. I wrote a full article about my connectivity here, so I won’t elaborate too much on this electrical article.

5v USB Step-Down

This is actually a recent addition to my van. This device provides me with two standard USB outlets. Connected to this device is my Jetpack Verizon hotspot (I wrote an article about it here) and my LED accent light strip. My hotspot is always on (or unplugged), and my LED strip is controlled via an app or remote, so I don’t have a power switch on this circuit at all.

Television

I really wanted to have an actual television in the van, but I wasn’t sure what size would work. I had issues finding TVs that ran off of a 12v supply. This one didn’t come with a 12v adapter, I just cut off the AC adapter brick and wired the plug to my 12v system. Biggest complaint: the speakers suck. I’m using this with a Chromecast without issue. There are larger units on the market that I’ve seen since, but a larger screen generally means more power usage.

Propane Alarm

If your build includes a propane tank, even in a sealed propane locker, this is a non-negotiable item. There are not a lot of propane alarms on the market. These have a 5-year service life, and the electrical draw is around .1 amps. I have it hard wired, with no switches. This is one device you want on, no matter what. You want to mount this as low as you can, and as closely to your propane and/or propane appliances as possible.

Refrigerator

I ordered two of these via EBay and both arrived with damaged plastic housing. It’s been running non-stop for over a year without issue, so overall, in a very expensive category (12v fridges), I still recommend this unit. I have been okay without a freezer, but do put some thought into what you need. This unit has been surprisingly spacious and cycles relatively infrequently.

MaxxAir Fan

Oh, MaxxAir… how I loathe thy company and adore thy product. This fan is great, has “ceiling fan” mode, “auto” mode (78 degrees F), fully motorized, can be used in the rain… the downside? My remote died and the company literally replied 4 months later, telling me that if you have an iPhone, it blocks the infrared sensor of the remote. Despite the fact that my remote works just fine if I use it in my friends’ vans. The upside is that you really don’t need a remote in a van. Pro tip: You may think you want this right over your stove, but I think I’d personally install it over my bed next time.

USB / Accessory Outlets

This is installed next to my bed for device charging. The Accessory outlet lets me plug in standard 12v automotive devices, like my 12v DJI drone battery charger.

Diesel Heater

This heater has been incredible. I’ve done a full article about it here. On the electrical front, few things to know: the heater will always pull at least 1.4 amps when it is powered on (the fan will always be on low, it doesn’t cycle on/off with temperature). Being a diesel burning heater, it has a glow plug. This glow plug pulls ten amps for up to two minutes on startup AND on shut-down. You do not want to put a switch on this circuit, a sudden power loss without the cool-down cycle will result in a bricked heater, from all accounts I’ve read.

Dimmer Switch

Rather costly for what it is, unfortunately I wasn’t able to find many 12v dimmer switches on the market. What I can say is: it works great with the 6 LED lights in my ceiling. Speaking of the LED lights in my ceiling…

Ceiling Lights

I wasn’t too sure about these, but I’ve been really happy with them on the road. Warm white is the way to go. I wired these up in parallel as was recommended by the manufacturer. I’d highly suggest wiring multiple “zones” via several switches or dimmers for two reasons: sometimes you don’t want 5+ lights on and it’s a waste of power to run them all simultaneously.

Switch

I didn’t actually have a purpose for both of the switches when I bought this! For 7 months, one of the switches was a killswitch for my water pump and the other was unused. Now, my cell booster is wired to the second switch. Always build a little room into your system for expansion!

Water Pump

I have had no issues with this pump, other than it being incredibly loud. I’ve read that this is the case with most pumps. Insulating your water lines and suspending the pump from a mount (rather than mounting directly) are supposed to significantly decrease noise, but I’ve not done this myself yet. I installed this with a switch inline (see below), the last thing you want is a pump that runs automatically whenever there’s a pressure drop with no killswitch. I turn this off anytime I don’t need water. If there were a pipe or hose leak at some point, it would run indefinitely.

Cell Booster

Absolute necessity if you camp outside of cities. I wrote a full article about my van’s connectivity here. This unit comes with a standard 12v cigarette lighter style adapter (with an integral power switch). I cut off the cigarette-lighter plug and wired the remaining cable into my van through the two-switch panel above.

DC Circuit Breakers

The listing above has numerous choices from 20-60a. This is a fantastic way to provide protection to your circuits AND provide for an easy way to disconnect components. I have one of these (20 amp) on my panel input cable – so I can disconnect my panels before servicing the charge controller. I have another (40 amp) on the positive line from my Sterling Battery to Battery charger so I can easily disable charging from the Transit alternator. A 60 amp can disable my UPS from charging the batteries (and protect against catastrophic failure in the event the APS-750 fails, per the manual). Lastly, a 30 amp allows me to quickly disconnect the charge controller from my house batteries for service. These breakers protect the lines from overvoltage (while allowing for easy reset without any kind of fuse replacement) and allow you to isolate issues in your system by easily disconnecting entire systems. Highly recommended!

Closing Thoughts

There’s a ton of wiring to be done, and you must do some research on exactly what type of terminations you need– along with what gauge cables to run. It’s not one-size fits all for this system. I encourage you to utilize a cable gauge calculator like this one at WireBarn and always err on the side of caution. For gauges larger than 6, I opted to measure and then order pre-terminated cables from Amazon and EBay. Once the wires are too large, you’ll need special crimps to make the terminations. For a project this size, I didn’t want to invest the time and money into learning to do this and purchasing the tools.

I highly recommend ordering the tools and supplies I’ve laid out in my article titled “My Basic Automotive / Van Build Electrical Tool Kit“.

Crimp connections should be made with proper crimpers, all solder joints should be heat-shrunk. I only use heat shrinkable crimp-on terminals. The shrink adds another layer of security to your crimp, in addition to preventing potential shorts and water intrusion.

Consider whether or not you need to remove a device when choosing terminations. For a propane alarm, a permanent solder joint is appropriate. For something that may wear out or break, like my USB outlets, I chose to use m/f quick disconnect crimp terminals.

I could likely go on for days, but please feel free to reach out to me via Instagram if you have any questions about my setup (or your future one).

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