Would just a 2 way switch do the trick? Your solar charger output can be switched between your batteries.



On edit I am curious if an isolator should be added between the truck battery and solar charger so that you wouldn't be back feeding the solar charger when you were running the engine.

Battery Selector Switch 2 Position 12V might be what need

Oh that looks perfect! Thanks! That should still keep the 2 electrical systems isolated as well correct?

Yes I do believe so I have on to bypass my battery's to a grid tie unit .

I used one of the switches RV Solar recommended to isolate two battery banks back when I was still had the OEM RV 12V battery and added 2 6V golf cart batteries for boondocking power. I'd use the switch to charge them separately, then keep the single 12V as an extra reserve battery. Worked great. https://www.loveyourrv.com/trojan-battery/

Thanks Ray. That's similar to what we have. 2 6v fur the coach and 1 12v for the engine. I think what's killing it is the radio. We use it a lot and I think it's not wired into the living area but to the engine electrical. But I'll definitely be getting that switch!

Who wired the system may I ask?

On our motorhome? I'm not sure - we are the third owners. I'm thinking the original owner as the previous owners only owned it for a year and took it out only a few times. As far as we know the original owner has passed, but he was full time for many years in it.

I keep finding weird little things that need to be fixed. Nothing serious. Just things like switches in the dash that don't do anything. The electric element to the water heater was disconnected. Little stuff like that.

when you switch from one battery system to the other, should you make sure that the solar charger has the battery connection before solar panels are connected?

On solar chargers I have worked with they recommend connecting the 12v power before engaging the panels. Best bet is to read the manual for your charger. I installed a circuit breaker between the panels and the charger which allows me to disconnect the panels easily.

I have a followup question now. I got my switch and will install it soon. Is it OK to have all the ground wires connected to each other? IE the ground from the starting battery, the RV batteries and solar ground all grounded together?