I’ve always had trouble with sealed lead acid coach batteries dying after a season or two. The new RV came with two wet lead acid 67 AH marine batteries that were pretty much shot. So I did some research and decided to make the expensive jump to lithium batteries.
This project required a lot of new equipment. Not only the two 105 AH LION Safari lithium batteries with the built in BMS but the new charger/converter, the DC to DC charger, a 30 amp transfer switch, a surge protector, and then for good measure a 3000 watt inverter.
I bought the LION batteries because two of them fit in the under stair battery compartment. Many 100 amp lithium batteries are 13 inches long and the compartment is only 12 inches. I saw these were for sale previous years at Costco but they were not being offered when I looked. I ordered them from another company but it turned out they were not in stock and they were waiting for a shipment from the manufacturer. In the meantime they came back to Costco so I cancelled the first order and bought the two with the special price of $799 each for two. They arrived almost immediately and I started buying the other components.
After much research on rv.net and other sites I decided to buy the new Progressive Dynamics 60 amp converter/charger to replace the WFCO 55 amp that came with the unit. This is the new version from the company and it has two stages, a bulk stage of 14.6 appropriate for lithium batteries and a float stage for when the batteries read full.
I removed the WFCO under the distribution panel but I installed a Progressive Industries surge protector there instead and installed the charger closer to the batteries. The refrigerator is located next to the entry in this 25b and the batteries are in the entry step. I learned there was enough space under the refrigerator by reading the answers to someone’s question about the location of the water tank. Of course using this area was no easy task with the tiny spaces to run wiring and place the new unit. I put it in and took it out multiple times before I was able to close it up and install the ventilation grate. In fact I completely installed the first unit only to have it not operate. It was an Amazon warehouse item and I think it was broken. So I returned it and bought a new one that did work.
The charger is wired with #2 wire and I bought the flexible type because I had to run them under the RV through a hole I drilled in the floor and over to the battery box. The charger connections are for #4 wire. I thought I would have to use pigtails between the #4 and #2 but someone on rv.net suggested wire reducers that clamped the wire to a rigid connector that fit in the #4 clamp on the charger. You can see them in the charger wiring photo.
The battery monitor wiring and the ground for the whole unit also go through that hole in the floor. I was out of room for the inverter remote wires and had to drill a new hole next to the first one. I also decided to go up the wall between the entry and the refrigerator for the wired remote so I would not have to bend over to turn on the inverter. I started a hole under the refrigerator and hit styrofoam so I moved it over to the wood.
The two new batteries were shorter than the battery box so I had enough room for the wiring and the DC to DC charger that is supposed to provide the correct voltage to the batteries while also protecting the truck alternator from burning out. Although most commentors say burning out a modern inverter is unlikely, the DC to DC charger still modulates the charge to the lithiums so that they get the proper charge routine.
The solenoid and incoming power are connected in the smaller box in the step. I had to drill a hole through the metal to insert the positive wire and connect it to the ANL fuse. I also had to run a wire (yellow) from the solenoid ignition signal connection to the charger as this tells the charger to operate. It won’t run without this signal. In this photo the battery studs are clearly visible. I removed the battery tie down and replaced it with the battery shipping foam.
It took me several weeks to figure out the components and how they should be wired. I downloaded several articles and diagrams to help me understand what was going on. In the beginning I used this one to get a general idea of the system.
The diagram is missing a DC to DC charger but it seems it might be a lead acid system. It also helped to download the Winnebago wiring diagrams so I could tell which wires were performing which tasks. In the battery box I had to figure out which connection was the incoming power to attach the DC to DC wiring and where the solenoid got the signal from the ignition to turn on alternator charging.
The instructions for the devices were pretty straightforward although I watched You Tube videos of people discussing a new charger install and took screen shots of the steps to remind me of the process.
After finishing the wiring for the chargers, the next step was installing the inverter. When I had all the recommended #00/2 wiring installed, the first inverter I ordered was damaged. I tried Amazon Warehouse again to save money but it was not a tested unit and just looked good to the eye. I had to spring for a full price unit and send that one back. Maybe I have learned my lesson about used electronics.
The battery wiring is rather crowded with the 00/2 gauge wiring on the smart shunt and the battery. The smart shunt is a Victron bluetooth battery monitor so it is not such a big deal that the monitor is below the refrigerator, I can connect to it with my smart phone. I put the inverter remote control in a higher position. The inverter is in the dinette seat literally next to the battery box in the step. The wired remote is in the entry at eye level from the steps.
After I had all the new equipment wired I installed a Renogy 30 amp transfer switch. Luckily there was room for the transfer switch in the basement compartment where there is other wiring and plumbing. It is right next to the distribution box under the bed. I already had a hole drilled through the distribution box into this compartment for the charger wiring. When I put in the transfer switch I had to remove the wiring in the distribution box and lengthen the wire from the surge protector to reach the new transfer switch. I also had to rewire the extension cord that I used to plug in the new charger/converter to the transfer switch. Because the switch connector only took one wire, I cut a short pigtail for the charger cord. Then the transfer switch was wired back into the the main power breaker. This removed the charger from its normal breaker and essentially put it on the main breaker. Now the refrigerator is on the old breaker by itself.
I had a difficult time understanding how the switch would work for the inverter instead of working between the generator and shore power which is one of the main applications. I have always used the manual method to make this switch. When we unplug from shore power we plug into the generator power outlet in the external power compartment. I could put in a separate transfer switch for this but I don’t think we need it.
This diagram helped me understand how to wire the transfer switch for the inverter. Both the shore power which is also the generator and the charger power are on the same side of the switch. This means that the charger will only run when getting power from either source. When the inverter runs it should not also be trying to charge the batteries. That is an endless loop that won’t go anywhere. It will deplete the batteries rather than charge them.
Figuring this out was rather complicated but it was also fun to read the manuals, study the diagrams and then look at my notes to digest the information and understand it. I’m hoping this equipment lasts for the life of the RV.