well the only battery the charger is near is the starting battery. I do not think the charger is hooked up at all. The neg wire that should run to the neg battery post is off but the red wire is hooked up. I talked to Nobles MArine and they said they just forgot to hook up the neg wire when they were hooking up the batterys. But up front there is a box in the floor thats has the batterys for the 24v t/m, and a ac plug. I am not sure if it is hooked up or what???? I mean whats the worst that can happen? So I go ahead and hook the neg wire coming off the charger to the neg post wich is on the cranking battery but i am not sure if there are any wires hooked up to the front batterys to charge......