Farmer Folly
I had my dealership install an emergency battery jump start from the coach batteries to the chassis battery so if my chassis battery were dead, I could add a charge from the coach batteries to "jump" start the chassis battery. You have to add a solenoid to the circuit between the two battery setups and the switch. If that is what you are looking to do. It has saved me a few times in the past. I also have a 100 watt solar panel on the roof connected to my coach batteries.
Paul
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