Adding a Starting Battery…

The attachments describe a change from 2 batteries (Group27 + Starter battery) to house bank of 2 grp27 plus one starting battery.  The change was made to our Mark 2 (1990), with minimal cost for materials.

In addition to the G27 and existing 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 quarter berth.  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.

Joe Orinko 1990 C30 #5805 433 Lincoln Avenue Erie, PA 16505 814 456 6469 unicorn@velocity.net

Power Diagram old
Power Diagram new
House Bank under Strbd Settee
Open Battery Box

 

Power Diagram old
Power Diagram new
House Bank under Strbd Settee
Open Battery Box

 

Power Diagram old
Power Diagram new
House Bank under Strbd Settee
Open Battery Box

 

Power Diagram old
Power Diagram new
House Bank under Strbd Settee
Open Battery Box

 

Power Diagram old
Power Diagram new
House Bank under Strbd Settee
Open Battery Box

 

Power Diagram old
Power Diagram new
House Bank under Strbd Settee
Open Battery Box

 

Power Diagram old
Power Diagram new