Solar and Battery Upgrades

Solar and Battery Upgrades

As we plan to do a fair amount of boondocking, we wanted to install a solar array and upgrade the battery bank. The rig came to us “Solar Ready” which simply means there are wires pre-run to an entry gland on the roof with MC-4 connectors for connecting a single 100W panel. In addition there is a small GoPower PWM solar charge controller preinstalled along side the step well. Thor provided 4 6V lead acid golf cart batteries that I believe were rated for 200Ah in their series+parallel 12V configuration. Being lead acid, we could only use 50% of that capacity without damaging the batteries. In the weeks leading up to this project we clocked nearly 24hrs of genset runtime just to maintain the batteries. Our plan is to remove the lead acid batteries and replace with 6 100Ah Lithium Iron Phosphate (LiFePO) batteries from Battleborn. That will give us a full 600Ah of useable capacity while also saving some weight and maintenance headaches. Here is what we are installing:

  • 6 100Ah 12V Battleborn batteries wired in parallel. (600AH Total useable)
  • 6 160W Renogy Solar Panels wired 3 pairs in parallel (960W total)
  • 1 Victron MPPT 150/85 Solar Charge Controller
  • 2 Victron Multiplus 12/3000/120-50 120V Inverter/Chargers wired in Split phase 180º
  • 1 Victron BMV-712 Smart Battery Monitor
  • 1 Victron Color Control GX
  • 1 Precision Circuits LiFePO4 Battery Isolation Manager
  • 1 Precision Circuits Battery Guard

All of the above connected via Victron VE Direct bus and/or VE Net wireless bluetooth network.

I removed the stock lead acid golf cart batteries from the drivers side battery bay and cleaned up that compartment a bit. That space still holds the pump for our leveling jacks, the propane distribution manifold and the breakers for the house systems, generator and jacks. With the batteries removed, there is ample room for a tote with our septic hoses and accessories. This is a good place for such things as this bay is open to the outside air. Also installed here is the ventilation fan and filter for the new battery and electronics bay located behind the back panel of this bay on the camp side.

The new Battleborn battery bank is located above the frame rails in a space accessible from the forward camp side compartment. That space is ideal as it will center the battery weight and is the perfect size and shape to hold the batteries. I made up a plywood base covered it with some outdoor carpet and added some aluminum angle stock to keep the batteries positioned on the base.

New battery bank
Test fitting of the 6 new Battleborn batteries in their planned location.

The walls of this bay are “Rotocast” ABS plastic. While nice and watertight, they are not the best for mounting heavy equipment. All of the gray carpet I installed on 1/2 plywood panels to line the compartment and give me good mounting surfaces for the rest of the equipment. I think this looks nicer than the black plastic as well.

I mounted the inverters and solar charge controller in the larger section of this bay, then laid out the positions of the fuses, breakers and disconnect switches. I had to make 2 long runs of 6/3 Rome from this bay back to the distribution panel under the master bed. I added a Square-D sub panel with a 50A double pole breaker next to the existing 12/12v distribution panel. I moved the 6/3 feed from the transfer switch to the new sub panel. From the new panel, one of my 6/3 runs feeds shore/genset power to the multiples inverters (One leg each). The AC Out of the Multiplus units runs back to the original 12/120 distribution panel via the second run of 6/3. Thor provided a 200W pure sine wave Xantrex inverter that is set up to run the residential fridge, the TV’s and one or two outlets. When on shore power, genset or running off the Victron Multiplus units, the Xantrex unit just passes the AC through. I decided to keep the Xantrex inverter installed. This way if I take the Victron units offline for any reason, the Xantrex unit will keep my fridge running.

Beneath the MPPT charge controller are 3 DC Circuit Breakers. 200A between the charge controller and the battery bank, 100A between the solar panels and the charge controller and 300A to feed the house systems including the Xantrex inverter. These breakers also act as disconnect switches. Hiding in the shadows beneath the Multiplus units are 400A ANL Fuses and a disconnect switch for each inverter. Along the bottom of the rear panel is the Battery Protect module. This will auto-disconnect the house loads if the battery bank voltage drops to a preset level. I could wire a remote house disconnect switch to this but haven’t felt the need yet so it is currently jumpered into the always on state and will disconnect if the voltage gets too low. The LiFePO Battery Isolation Manager is installed in the old battery bay replacing the one provided by Thor trat was designed for the lead acid battery bank. On the righthand wall holds the shunt, negative buss bar, a small 12 fused distribution panel for the gauges and panels installed in the coach, the 12V outlets in this bay and the bilge fan system. This was also a convenient place to mount a 12V battery charger for my Ryobi One+ power tools.

This bay was not ventilated at all. The Multiplus units and the MPPT charge controller all generate a fair bit of heat when in use. I ended up cutting 2 3″ holes in the rear panel behind the battery bank and installed a bilge fan with an air filter on one of the openings and a screen to cover the other. I added a cheap electronic thermostat controlled relay and programmed it to turn the fan on at about 90ºF. The fan blows fresh air from the open air compartment on the opposite side of the coach into this bay and forces the hot air out of the other opening. So far this seems to be keeping things at a reasonable temperature.

Inside the coach, I installed the display for the Victron BMV-712 Battery Monitor, the Victron Color Control GX panel and two Blue Sea Systems OLED meters – One for Battery Voltage and the other to monitor the electronics bat temperature.

Victron Color Control GX, Victron BMV-712 Battery Monitor, Blue Sea Systems OLED Voltage and Temperature Gages installed. Original GoPower PWM Charge controller (unused) and Xantrex Inverter remote panel visible across the bottom.
The display of the Victron Color Control GX via the Victron Portal.

I mounted the 6 Renogy 160W Solar Panels on the roof and wired them into 3 pairs in series then those pairs parallel to the entry gland that Thor provided. The other end of those wires went to the GoPower PWM charge controller that came with the coach. The is located directly above the bay were I installed the Victron charge controller so and the wires actually were routed through that bay. All I needed to do was disconnect them from the GoPower unit and pull them back into the bay. Quite convenient! I toyed with the idea of building a combiner box on the roof for all of the panels to run into but got lazy and just used come MC-4 Y adapters to gang everything together right before the entry gland. Not the prettiest work I have done but quite effective and very easy to change if I need to.

I made my own mounts for the panels out of some 6160 structural aluminum T and angle stock. My plan was to make the panels tiltable to optimize their angle for spring and fall use. This also allowed me to keep the panels as low profile as possible when laying flat so as not to impact our already excessive clearance of 13’3″. I haven’t yet made the lift rods to tilt the panels with but I hope to get those done before fall.

As of the writing of this post, the system has been installed and running for a little over a month now. The system is proving to be very capable. The only time we have needed to run the generator since installing the system was to warm it up for an oil and filter change. This system allows us to run the coach as though we were plugged into a full 50 service and provides a full 220VAC across both legs. With the dual inverters each handling their own leg of the AC service we can run several high draw appliances simultaneously. While we “can” run the air conditioners from our batteries they would consume our battery capacity fairly quickly so those will most likely only be run while on shore power or running the 5.5KW geneset. I do plan to run a test in full sunlight to see if the solar array can offset the air conditioner enough to not impact the batteries. We will certainly have more to say about this as we get to spend more time boondocking and taking advantage of the capabilities offered by these upgrades. As of now I highly considering a system like this if you plan to be off grid for any length of time.

I spent more on this project than I had originally planned. Much of the excess was the cost of the heavy 4/0 and 2/0 gage wire necessary to interconnect the batteries, Multiplus units and the MPPT charge controller along with the lugs and tooling necessary to work with these materials.

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