Dual Battery Question

[Jim H]

The new boat has dual batteries with a Perko dual battery switch (the one that has OFF - 1 - ALL - 2). Previous owner said he always ran the boat in the ALL position.

If I do that, doesn't both batteries get put in parallel? I don't think that this is the best way to run/charge the batteries. I've read that you should select one (or the other!) battery and then use a different battery each trip to keep both in good shape. Only use ALL when one battery won't start the motor. What is the proper procedure?

I also know that you NEVER want to move the switch to OFF when the motor is running. This will create an infinate load situation and blow the alternator.

Also wondering how you manually charge a battery with a battery charger. Do you put the switch to OFF and connect the charger to the battery you need to charge? Can this damage the alternator? Should I disconnect the battery prior to manual charging?

Thanks,

Jim