Cells?
Peter -
I had trouble with my coach batteries of my 2015 Sprinter Chateau right out of the chute. It being brand new and all I failed to suspect the most basic thing - condition of the batteries. When I finally got around to them I discovered they were mostly dry. Adding electrolyte didn't help; they were already too far gone.
Sorry, I can't begin to imagine what might drain them if the battery disconnect switch is in the off position.
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