1. It's easy to check for parasitic draw by disconnecting a cable and placing ammeter between terminal and cable. I suppose the question would be whether disconnecting the power source would cause loss of important memory in any of the boards.
2. I'm new to RV ownership, but have been a motorcycle owner for over fifty years. A great battery aid is a conditioning trickle charger. BMW makes a good one, and there are others. When I bought our RV the house battery was low, apparently from sitting on the dealer's lot. I charged on a 30 amp charger until it was fairly well up but did not register as fully charged, then attached my old motorcycle trickle charger which brought it up to full charge in about 12 hours.
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