I decided to expand the battery system on our C30 Mark 2.
In addition to the G27 and starter battery in the battery box under the Starboard Settee,
I had an extra deep cycle G27, from a previous boat.
Without getting into inverters, isolators, -combiners, etc, I just wanted to add ampacity to the house bank, and keep the starter battery topped off for turning over the motor.
Wiring the 2 deep cycle batteries in parallel makes it appear as a single big battery with twice the amps. The ‘1-both-2-off’ switch on the panel works as before; charger has its own leads, so charging at the dock will charge both banks (all 3 batteries).
I choose to locate the starter under the aft quarterberth. I figured the wire length (voltage drop) would be no worse than the current configuration. I only had to add the ground cable (#2 welding cable from the electrical supply store; they crimped on the ends) from the starter battery to the engine block, and the platform to hold the battery.
The platform is plywood, coated in epoxy. It has 3 legs made from bolts from the hardware store. Once I had the platform level, I mixed up some epoxy and glued the bolt heads to the hull. I already had the battery box, and I bought the battery strap from WM.
Last summer I was working for GE Transportation Systems, so I couldn’t swing a cat without hitting an electrical engineer. Several engineers sprinkled the plan (diagrams) with holy water, so I had high confidence.
After one season, it works. Now on the hard, I took some pictures (which match, but don’t look like, the diagram).
Any questions, you can contact me.
1990 C30 #5805
433 Lincoln Avenue
Erie, PA 16505
814 456 6469