[Foldbak]

You are correct however the breakaway switch is a no load circuit in the normally open position. Therefor no drain. See below. The only thing connected to the positive side of the batteries before the disconnect switch is the (no load) breakaway switch and the positive side of the auxiliary solar port which if a panel were connected would charge the batteries. So there is no drain with both inverter and battery disconnect switches off. Now if the positive side of the battery were corroded to the battery case there would be a drain to ground.