Below is my latest diagram to install off-grid power in my RV which is a 5th Wheel camper.
Setup
tow vehicle: F350 with 2kW Pro Power Onboard
MultiPlus-II 2x120V
2 x 320Ah 12V LiFePO4 batteries in parallel
Cerbo-S GX
GX Touch to monitor all sensors
50A surge protector
This will provide sufficient power for 120V and 12V appliances. I will charge from the towing vehicle’s 2kW inverter while driving. To do that I will need to reduce the MultiPlus draw to avoid overloading the 2kW power and then change back when I have shore power. I could use a DC-to-DC charger but that will require a 22 foot (6 meter) 4-gauge wires from the front of the truck which will incur voltage drop. I will use the 2kW for now and if that does not work out can go the other route.
The green labels in the diagram represent wire gauge and I believe this is sufficient for the load. The batteries and all other equipment will be located close together, so distance will not be a huge factor.
Let me know if anyone can spot a flaw in this design or have recommendations. Also let me know if you would do it the same way as that will help me understand that I am on the right path.
Looks good from my recliner, though I’d probably run power to the cerbo so it’ll work
I went with a pretty similar setup but chose to go with a 24v multiplus and kept my existing 12v system separate. Saves a bit on wiring and unit cost, though a little more complex. It just uses the original 100a converter in the trailer to charge/supply the 12v
In your setup I think the only other thing I would suggest is a second disconnect switch that would allow you to isolate the multiplus and the rv 12v separately should you find yourself in a scenario where one or the other needs to be taken offline, you can still retain function on the other.
Your ac wire gauge is pretty overkill and likely wouldn’t fit the connections, definitely not on the multiplus. 4awg is sufficient for the 50a 120v rating. I would also personally keep the jumpers between batteries sized to 4/0 as under sizing there could lead to potential issues in the future as batteries become imbalanced, you could end up pulling more amps than intended through the 1/0
Thanks Dave, great idea about the disconnect switches, I will add that to the design. It makes sense to keep the jumpers between batteries at 4/0, that way I only need to buy one size wire, so I am good on amps and save money. I will check Victron specs again for the MultiPlus, I thought that was where I got the size, but there will be many other diagrams also to cross-check before I purchase anything.
