Re: Dual batteries
What will be the purpose of the second battery. If its for a trolling motor or house battery, that battery should be a deep cycle. When you say "adding a charging system" what do you mean. The second battery can be charged from the engine electrtical system however if it becomes deeply discharged, it will not get recharged in short runs. This is especially true if its used to power a trolling motor. If you mean you are adding an on-board smart charger that works from shore power, thats a separate issue. If you will use the second battery as a house battery and back-up for the starting battery, you should install a battery switch. Make sure its a make-before-break style. You can then shut off both batteries, start on BAT 1 or BAT 2 or BOTH. When anchored you can switch from BAT 1 (start battery) to BAT 2 (house) so you don't discharge the starting battery. You can then switch back to BOTH or 1 for the trip back to the dock. Both batteries will charge in the BOTH position. Only the selected battery will charge in BAT 1 or BAT 2. You could also add an isolator so both batteries are charged regarless where the battery switch is set.
