Update September 2020. It’s been a bit over a year since I installed this electrical system into my third build (Miles Van Camper v3). It has performed very well out there on the road and I’m quite happy with it. However, I’m always learning and always looking for better means and methods. I also work with tons of individuals building their own van. And, over the summer of 2020, we began work on our Vanlife Outfitters store which required us to carefully consider what products we wanted to sell to other DIY van builders. This lead to even more research. The end result is this new electrical system that I consider the best approach for most van builds.
Disclaimer: this is not electrical advise. Rather, this is an illustration of an example electrical system that we use in our vans and customize as needed. Always do your own research and use this information at your own risk.
I detailed the electrical system in Miles Van Camper v3 in this PDF wiring diagram.
Components and Materials Used
2x Renogy Lithium-Iron Phosphate Batteries. Each battery has 100 amp hour of capacity and they are wired in parallel to provide a total of 200 amp hours of usable capacity. I left space for a third battery in case I wanted to grow the system in the future.
Many people also use the 100 amp hour Battleborn batteries which are slightly better but also more expensive.
Renogy 2000 Watt Pure Sine Inverter/Charger. This “newer” (at the time of this post in September 2019) supports charging lithium batteries. Inverters take the 12 volt DC power from your battery(s) and convert (invert) that to standard household voltage which is 120 volt AC so that you can operate household electronic appliances. In my case it powers things like the microwave, computer chargers and the rooftop air conditioner for short periods of time. Anytime you connect to “shore power” (plug your van into an outlet at a campground or host), the inverter will automatically transfer any loads to that shore power connection and it will use that electrical connection to charge your batteries.
Note: this inverter ONLY charges lithium batteries when the voltage drops below 12.5 when using the lithium charging settings. In other words, unlike AGM or other lead acid batteries which get charged anytime you’re connected to shore power, this only charges the lithium batteries when they are fairly drawn down. I wrote to Renogy about this and after a few weeks of “checking with their engineers” I received this in their response “please note the inverter/charger will recharge Li batteries but as stated in the manual; you will only be able to recharge the Li batteries when the battery voltage drops below 12.5 volts and charging will be suspended once the batteries reach 14.7-volts.”.
Renogy 40 Amp DC to DC Charger. These are also known as “battery to battery chargers”. Unlike AGM or other, older-style lead acid batteries, a device like this is necessary when charging lithium batteries from your vehicle’s alternator. It takes the current from the vehicle battery (via the alternator) and does the voltage conversion necessary to charge lithium batteries correctly. Notes on the installation of this unit below in this post.
Note: there is also a 60 Amp version of this which I intend to upgrade to in the future. It should be a direct swap out since I used 2 AWG wire for the run between the Promaster battery and the DC to DC charger!
Renogy Rover, 40 amp MPPT Solar Charge Controller. Your solar panels connect up to this charge controller to ensure that batteries are charged correctly from the panels. It also supports the charging profile required by lithium batteries.
Victron BMV-712 Battery Monitor. This allows you to track how much charge you have left in your battery bank, any charging input coming in (from solar, driving, etc.) and any draws from the battery. It can also transmit all this information via Bluetooth to a mobile device.
Progressive Dynamics 30 Amp AC and DC Load Center. This unit combines both your 12 volt DC fuses and your 120 volt AC circuit breakers into one integrated load center.
Wire / Fuses / Circuit Breakers / Etc.
Fastronix 3/8″ 4 Stud Bus Bar with Cover. I used a red one for the positive bus and a black one for the negagive bus.
2/0 AWG wire for connecting the batteries to each other in parallel as well as connecting the batteries to the inverter and to the positive and negative bus bar. I ordered black for the 12 volt negative connections and red for the 12 volt positive connections.
2/0 AWG lug connectors for 3/8″ studs. These are crimped onto the 2/0 wire to connect things together.
2 AWG wire for connecting the van battery to the DC to DC charger and from that device to the positive bus bar. Also used this wire to connect the positive bus bar to the DC input on the load center.
2 AWG lug connectors for 3/8″ studs. These are crimped onto the 2/0 wire to connect things together.
2x 200 amp circuit breakers. One is installed between the batteries and the positive bus bar and the other between the batteries and the inverter.
80 amp circuit breaker. This is installed between the positive bus bar and the DC input to the load center.
50 amp circuit breaker installed between the DC to DC charger and the positive bus bar. If you do upgrade to the 60 amp version of the DC-DC charger you can still use the 2 AWG wire but you’ll need an 80 amp circuit breaker.
2x 20 amp circuit breakers installed on the positive wire between the solar panels and the solar charge controller and between the solar charge controller and the positive bus bar.
50 amp mega fuse. This fuse is connected to the terminal on the van battery that feeds the DC to DC charger wire run from the van battery for alternator charging. If you do upgrade to the 60 amp version of the DC-DC charger you can still use the 2 AWG wire but you’ll need an 80 amp mega fuse.
Solar panel cable entry. This allows the solar panel wires to come through the roof through the waterproof “glands”.
Hydraulic crimper for terminating the heavy duty 2/0 and 2 AWG wires.
LED puck lights installed throughout the van.
Goosneck LED reading lights installed in the bed/loft area.
14 AWG extension cord. I remove the ends on this and use the wire for 120 volt AC branch circuits (outlets, microwave, etc.).
12 AWG flexible marine wire for 12 volt branch circuits (lights, refrigerator, charging ports, etc.)
30 amp shore power inlet installed on the driver side of the van near the rear wheel to connect the van up to shore power. Incidentally, the white plastic on this inlet tends to yellow in the sun quickly so I recommend you paint it white (or whatever color) with a high quality spray paint before installing. I considered some of the more expensive models but that really is the only down side to this one that I’ve found and it’s quick to paint.
15 amp to 30 amp adapter to use plug the van into a standard household outlet with with 30 amp shore power cable.
Holding tank heating pad. I used this on the grey water tank as well as a few of these on the sink drain – both underneath the van. They are wired together through a switch that I can turn on to keep the drain lines and tank from freezing in cold weather.
Connecting the Renogy DC to DC Charger to Ignition Switch and DIP Switch Configuration
Unlike some other battery-to-battery charging products that sense voltage and trigger the charging based on that, the Renogy DC to DC charger (or battery-to-battery charger) that I used requires you to connect up a 12 volt positive “signal wire” from the vehicle’s ignition switch so that it only charges from the van (vehicle) battery when the ignition is turned on. Without this ignition trigger on this unit or the voltage sensing on others, the battery-to-battery charger could easily drain the van battery since the battery-to-battery charger would be pulling current without the alternator providing a charge.
After some research I discovered that Promaster vans have a “Upfitter Connector” on the passenger side “pillar” which is that area just behind the passenger seat where the seat belt connects tot he van wall. If you remove the black plastic trim at the bottom of this “pillar” you’ll see a white multi-pin connector (photo below). This is the “upfitter connection” that provides a variety of connection points for the Promaster in one spot. This PDF file (Promaster Upfitter Connector Diagram PDF) details this connector including what each pin on the connector is/does. Turns out that pin #13 is an “ignition feed” that has 12 volt positive when the ignition switch is on. So, I used this to be the “trigger” for the Renogy DC to DC charger.
Close Up Shot of Promaster Van Upfitter Connector with Pin #13 Connected:
In order to do this, I had to order the correct, “male” version of this connector as well as the “pin” itself. The way this works is that you solder the correct wire to an empty pin and then insert that pin into the correct position on the connector thus allowing you to access and wire up a variety of things to this upfitter connector. These parts are pretty inexpensive so I bought a few with the expectation that I’d destroy a few figuring out how this all works. I’m glad I did because I did indeed destroy a few experimenting. Ultimately, it’s not difficult but finding the right parts and how they fit together took some time. So hopefully this saves you that time!
Soldering the Wire to the Pin:
The wire coming out of pin #13 on the Upfitter Connector runs back to the rear passenger side wheel well where the primary electrical system is installed and is connected to the Renogy DC to DC charger on a terminal labeled “D+”. Below is a photo of this connection:
Next I had to configure the Renogy DC to DC charger to correctly charge the lithium batteries using the DIP switches pictured above. The manual for this Renogy DC to DC charger is really bad and the section on setting up the DIP switches is complete gibberish. I gave up on it pretty quickly and called into Renogy support. The correct DIP switch settings for charging lithium batteries with the Renogy DC to DC charger is:
- Switch #1: Off
- Switch #1: On
- Switch #3: On
- Switch #4: On
- Switch #5: Off
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