Harvestmoon
Senior Member
We have a 10 day off grid trip that we do annually, so prior to purchasing our 2023 22MLE in late fall, we started researching what we would need to meet our electrical needs, and particularly the 12V compressor fridge. Overall, I like the compressor fridge over the absorption fridge in our previous camper because it just works better. But it does change the energy budget when off grid. Our 22MLE came from the factory with the 165W Furrion solar panel, 25A MPPT controller, and lithium auto-detect converter. So that is a pretty good start. We had the dealer add on a second 165W Furrion panel. For sure, the Furrion panel is overpriced, but I wanted the panels to match and also knew I would not be able to stomach drilling holes in the roof of our brand new camper myself. I wasn’t sure yet what we wanted to do for batteries, but I knew the dealer’s standard FLA wasn’t it, so we took a credit for no battery. I temporarily threw on a spare FLA battery I already had on hand for the couple of short shakedown trips (with shore power) that we did in October, prior to putting the camper to bed for the long Wisconsin winter.
After exploring the 22MLE stock configuration, the vacant space under the rear dinette seat seemed like the obvious place for a couple of sealed batteries and an inverter. It gets the batteries over the axles, in a heated space, and right next door to the camper power center. I searched the forums and indeed found other 22MLE owners doing similar installs. In particular, SailorDan’s installation on his 22MLE was very similar to what I was planning. From a high level, the batteries are installed under the rear dinette seat and tie into the DC system at the converter. The inverter fits in the same space as the batteries, making those connections short and simple. The inverter 120V AC output ties into the outlet circuit by cutting into the wire where it leaves the 120V distribution panel and installing an auto transfer switch. This powers up all of the 120V outlets throughout the camper, which is the only AC power we intend to use when off grid. (For any heavy AC power needs such as microwave or air conditioner, we run a small portable generator.) For keeping the LFP batteries properly charged from the TV while on the road, I repurposed the original battery box to house a DC-DC charger.
Here are my main components:
2x LiTime 100aH LFP $300 each
Renogy 1000W pure sine wave inverter $190
Renogy 20A 12/12V DC-DC charger $110
Victron SmartShunt 500 amp Bluetooth battery monitor $130
Xantrex Prowatt auto transfer switch $70
Cables, circuit breakers, connectors, hardware, battery straps, etc. ~$200
So, all in all about $1300 in parts. I lucked out a bit with the LiTime batteries (formerly sold under the name AmpereTime). A couple of weeks after I bought the LiTimes, they raised their price from $300 to $350, reversing the trend of falling LFP prices over the last couple of years, at least in the cheap knock-off segment. So far, I’m fairly impressed with the LiTime batteries. On receiving them, they both had the exact same resting voltage of 13.17V, which (per the included tables), put them right around the 50 percent recommended long term storage state of charge. I had also purchased a 10A LFP specific charger, and the first task was charging up the batteries one at a time. After charging the first one, I discharged it through the Victron shunt to verify the 100Ah capacity. Since I needed to charge the second one, I amused myself by charging the second battery from the first one through the inverter and AC charger and also via the DC-DC charger just to test everything out. Both batteries reached 100Ah of discharge at just under 12V. I was satisfied with reaching 100Ah, so I stopped the discharge test before the BMS shut down. Then I fully charged both again, allowed them to rest until the voltages were stable and equal, and then connected them in parallel. To stress test, I connected the paralleled pair to the inverter and discharged through a 750W space heater for 30 minutes. The system handled this no problem. I fully charged the pair again and then plugged my full-size kitchen refrigerator into the inverter and ran it for 36 hours. That used about 150Ah. Satisfied everything was working, it was time to move off the kitchen table and into the camper.
I mounted the inverter, Xantrex ATS, Victron shunt, and a 150A DC breaker to a piece of plywood and then attached this assembly on edge to the front wall of the dinette seat. To pull cables through to the converter closet, I drilled a 2” hole through the wall. At the back of the converter, I tied #6 wire into the converter DC output positive and negative. This is also where the original cables from the front of the camper were tied into the converter. With this many heavy cables coming together, I replaced the factory wire nuts with split bolt type lug connectors and then wrapped the connections with insulation and electrical tape. The negative cable is connected to the Victron shunt, and the positive cable connects to the battery terminal through a 50A breaker with push button trip. For the inverter, I ran #2 cables. The negative goes through the shunt and the positive through a 150A breaker and then to the battery. The shunt negative is tied to the battery with 1/0 cable, and the batteries are tied in parallel with a pair of #4s. The positives are connected to one battery and the negative to the other battery in order to balance the resistance of the parallel ties. For physical mounting, the batteries are pushed into the corner against the seat framing and then blocked in with boards that are screwed to the floor. A pair of cam buckle straps loop over the top of both batteries and through cleats screwed into the framing to securely hold the batteries in place.
For the AC side, I found the 120V wire for the outlet circuit and cut this about a foot behind the AC distribution panel. At the cut ends, I connected a 15A extension cord type round receptacle on the source side and the matching plug on the load side. I installed the same type of connectors on the ATS primary input and output. Then I used short extension cords to span the distance between the ATS and the connections to the outlet circuit behind the distribution panel. The ATS secondary input plugs directly into the inverter. When on shore power, everything works seamlessly as normal. When on generator power, I leave the outlet circuit breaker turned off, because this circuit also powers the converter. Our generator is fairly small (2500/2000W), so when running on generator power, I leave the DC system running on solar/battery power so that the generator power can be dedicated to either the microwave or the air conditioner.
For charging while towing, I intercepted the hot wire from the vehicle 7-pin connector and routed that with #10 wire through a fuse and then to the DC-DC charger, which I mounted in the front battery box. The negative side of the DC-DC charger input is tied to a frame ground. For the charger output, I connected the original cables that would have been connected to the battery terminals in the stock configuration. For the DC-DC charger ignition sense wire (which turns on the charger), I connected this through a fuse and toggle switch to the TV input power. So any time the TV wire is hot, it will activate the DC-DC charger, unless the toggle switch is off. The TST tire pressure sensor repeater is also connected on the charger input side, so this will also power up when the TV is connected. I hard wired from the ignition sense terminal to the charger “low current” terminal, a feature which limits the charger output to half its rated current, so 10A on this 20A charger. I am limiting the TV charging to 10A, since I don’t want to over stress the factory trailer wiring and don’t really count on a lot of charging while driving. Mainly I just want to more or less break even with running the refrigerator while driving, in case there isn’t enough sun for the solar panels to keep up. The toggle switch allows turning off the DC-DC charger in case we are towing in sub-freezing weather, since the BMS in the low price LiTime batteries does not have cold charging protection. For this same reason, I put a 2 pole DC breaker/switch on the solar input to the solar charge controller, so that I can turn off solar charging as well.
I’ve tested charging the LFP batteries from the converter on shore power and also via the DC-DC charger by simulating TV power with a spare battery connected to the 7-pin. I have not been able to test solar charging yet since the camper is stored indoors and won’t be rolled out into the sun for a couple of more weeks yet. When working on the solar disconnect switch, I was surprised to find a decent amount of open circuit voltage on the panels just from some very filtered and indirect light coming through a skylight. Since I didn’t want to wait until dark, I put some heavy blankets over the panels for that part of the work.
Everything went pretty much as expected, except I uncovered some very poor quality crimp connections done by the factory where the DC circuits going out to the coach loads connect up at the back of the converter. I was gently moving some of the rat’s nest around just to figure out what was what, and one wire pulled right out of its crimp. It was a source wire and managed to touch something grounded and pop the fuse. So I killed all of the power and started figuring out what the heck happened, and found 3 of the 5 DC circuits had bad crimps. The wires were not fully into the connectors and a couple had stray copper strands poking out just waiting to find a ground. Needless to say, it was “off with their heads” and I redid these crimps. I’m glad I found these bad crimps during this project instead of having wires pull out on the road somewhere. The wire that pulled out was the power for the control panel, so that would have been fun rolling into a campsite in the dark to find a dead control panel and no idea why. I pray that the rest of the wire crimps buried in the walls and ceiling were not done by the same idiot who wired the converter. So far, all of the other visible crimps I have been able to see are good.
Overall, I’m really happy with how this turned out and can’t wait to hit the road with it as soon as it stops snowing. I welcome your questions and comments.
After exploring the 22MLE stock configuration, the vacant space under the rear dinette seat seemed like the obvious place for a couple of sealed batteries and an inverter. It gets the batteries over the axles, in a heated space, and right next door to the camper power center. I searched the forums and indeed found other 22MLE owners doing similar installs. In particular, SailorDan’s installation on his 22MLE was very similar to what I was planning. From a high level, the batteries are installed under the rear dinette seat and tie into the DC system at the converter. The inverter fits in the same space as the batteries, making those connections short and simple. The inverter 120V AC output ties into the outlet circuit by cutting into the wire where it leaves the 120V distribution panel and installing an auto transfer switch. This powers up all of the 120V outlets throughout the camper, which is the only AC power we intend to use when off grid. (For any heavy AC power needs such as microwave or air conditioner, we run a small portable generator.) For keeping the LFP batteries properly charged from the TV while on the road, I repurposed the original battery box to house a DC-DC charger.
Here are my main components:
2x LiTime 100aH LFP $300 each
Renogy 1000W pure sine wave inverter $190
Renogy 20A 12/12V DC-DC charger $110
Victron SmartShunt 500 amp Bluetooth battery monitor $130
Xantrex Prowatt auto transfer switch $70
Cables, circuit breakers, connectors, hardware, battery straps, etc. ~$200
So, all in all about $1300 in parts. I lucked out a bit with the LiTime batteries (formerly sold under the name AmpereTime). A couple of weeks after I bought the LiTimes, they raised their price from $300 to $350, reversing the trend of falling LFP prices over the last couple of years, at least in the cheap knock-off segment. So far, I’m fairly impressed with the LiTime batteries. On receiving them, they both had the exact same resting voltage of 13.17V, which (per the included tables), put them right around the 50 percent recommended long term storage state of charge. I had also purchased a 10A LFP specific charger, and the first task was charging up the batteries one at a time. After charging the first one, I discharged it through the Victron shunt to verify the 100Ah capacity. Since I needed to charge the second one, I amused myself by charging the second battery from the first one through the inverter and AC charger and also via the DC-DC charger just to test everything out. Both batteries reached 100Ah of discharge at just under 12V. I was satisfied with reaching 100Ah, so I stopped the discharge test before the BMS shut down. Then I fully charged both again, allowed them to rest until the voltages were stable and equal, and then connected them in parallel. To stress test, I connected the paralleled pair to the inverter and discharged through a 750W space heater for 30 minutes. The system handled this no problem. I fully charged the pair again and then plugged my full-size kitchen refrigerator into the inverter and ran it for 36 hours. That used about 150Ah. Satisfied everything was working, it was time to move off the kitchen table and into the camper.
I mounted the inverter, Xantrex ATS, Victron shunt, and a 150A DC breaker to a piece of plywood and then attached this assembly on edge to the front wall of the dinette seat. To pull cables through to the converter closet, I drilled a 2” hole through the wall. At the back of the converter, I tied #6 wire into the converter DC output positive and negative. This is also where the original cables from the front of the camper were tied into the converter. With this many heavy cables coming together, I replaced the factory wire nuts with split bolt type lug connectors and then wrapped the connections with insulation and electrical tape. The negative cable is connected to the Victron shunt, and the positive cable connects to the battery terminal through a 50A breaker with push button trip. For the inverter, I ran #2 cables. The negative goes through the shunt and the positive through a 150A breaker and then to the battery. The shunt negative is tied to the battery with 1/0 cable, and the batteries are tied in parallel with a pair of #4s. The positives are connected to one battery and the negative to the other battery in order to balance the resistance of the parallel ties. For physical mounting, the batteries are pushed into the corner against the seat framing and then blocked in with boards that are screwed to the floor. A pair of cam buckle straps loop over the top of both batteries and through cleats screwed into the framing to securely hold the batteries in place.
For the AC side, I found the 120V wire for the outlet circuit and cut this about a foot behind the AC distribution panel. At the cut ends, I connected a 15A extension cord type round receptacle on the source side and the matching plug on the load side. I installed the same type of connectors on the ATS primary input and output. Then I used short extension cords to span the distance between the ATS and the connections to the outlet circuit behind the distribution panel. The ATS secondary input plugs directly into the inverter. When on shore power, everything works seamlessly as normal. When on generator power, I leave the outlet circuit breaker turned off, because this circuit also powers the converter. Our generator is fairly small (2500/2000W), so when running on generator power, I leave the DC system running on solar/battery power so that the generator power can be dedicated to either the microwave or the air conditioner.
For charging while towing, I intercepted the hot wire from the vehicle 7-pin connector and routed that with #10 wire through a fuse and then to the DC-DC charger, which I mounted in the front battery box. The negative side of the DC-DC charger input is tied to a frame ground. For the charger output, I connected the original cables that would have been connected to the battery terminals in the stock configuration. For the DC-DC charger ignition sense wire (which turns on the charger), I connected this through a fuse and toggle switch to the TV input power. So any time the TV wire is hot, it will activate the DC-DC charger, unless the toggle switch is off. The TST tire pressure sensor repeater is also connected on the charger input side, so this will also power up when the TV is connected. I hard wired from the ignition sense terminal to the charger “low current” terminal, a feature which limits the charger output to half its rated current, so 10A on this 20A charger. I am limiting the TV charging to 10A, since I don’t want to over stress the factory trailer wiring and don’t really count on a lot of charging while driving. Mainly I just want to more or less break even with running the refrigerator while driving, in case there isn’t enough sun for the solar panels to keep up. The toggle switch allows turning off the DC-DC charger in case we are towing in sub-freezing weather, since the BMS in the low price LiTime batteries does not have cold charging protection. For this same reason, I put a 2 pole DC breaker/switch on the solar input to the solar charge controller, so that I can turn off solar charging as well.
I’ve tested charging the LFP batteries from the converter on shore power and also via the DC-DC charger by simulating TV power with a spare battery connected to the 7-pin. I have not been able to test solar charging yet since the camper is stored indoors and won’t be rolled out into the sun for a couple of more weeks yet. When working on the solar disconnect switch, I was surprised to find a decent amount of open circuit voltage on the panels just from some very filtered and indirect light coming through a skylight. Since I didn’t want to wait until dark, I put some heavy blankets over the panels for that part of the work.
Everything went pretty much as expected, except I uncovered some very poor quality crimp connections done by the factory where the DC circuits going out to the coach loads connect up at the back of the converter. I was gently moving some of the rat’s nest around just to figure out what was what, and one wire pulled right out of its crimp. It was a source wire and managed to touch something grounded and pop the fuse. So I killed all of the power and started figuring out what the heck happened, and found 3 of the 5 DC circuits had bad crimps. The wires were not fully into the connectors and a couple had stray copper strands poking out just waiting to find a ground. Needless to say, it was “off with their heads” and I redid these crimps. I’m glad I found these bad crimps during this project instead of having wires pull out on the road somewhere. The wire that pulled out was the power for the control panel, so that would have been fun rolling into a campsite in the dark to find a dead control panel and no idea why. I pray that the rest of the wire crimps buried in the walls and ceiling were not done by the same idiot who wired the converter. So far, all of the other visible crimps I have been able to see are good.
Overall, I’m really happy with how this turned out and can’t wait to hit the road with it as soon as it stops snowing. I welcome your questions and comments.
