J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Ignition switch replacement?

The J/30 original installation uses a battery switch that does battery 1, battery 2 or both. I use a very complicated algorithm to determine which battery to use. If it is an odd day, I leave the battery switch on 1 after the engine is shut down. If it is an even day, I leave the battery switch on 2 after the engine is shut down. This evenly uses the batteries over their life. I start the engine on both batteries, leave it there while running to charge both, and periodically will start on just 1 battery to see how it is working.

So what works for me is two of the same type battery. Some do a battery with high cranking amps for starting, and a second deep cycle battery for the house loads. Depending how you plan on using your boat, this may be a more preferred alternative. When I've done overnight deliveries, I just start the engine and top off the batteries after 6 hours running the navigation lights - that's the biggest current draw. The instruments are negligible compared to the lighting.

There are aftermarket voltage regulator and charging circuits that negate the requirement to use the battery switch for battery selection and charging like the Blue Sea Systems Automatic Charging Relay.

Probably way more info than you were looking for