Originally Posted by
Hotboat
Honestly I don't think leaving your perko on in any position is a good idea. Too many bad things can happen to a unmonitored boat or RV or anything for that matter.
You can use diodes to charge both batteries with the switch off and that will keep the batteries separate with the switch in the one batt position. But I would fuse the tender as well.
As far as trickle charging, I'm not a fan. But then again its been too long since I was in the battery business, so things may have changed, but I doubt it.
Trickle, float, tender, whatever they want to call it is still causing current flow in the battery. Current flow, over time, will age the cells. Batteries age even without a charge, so even a float charge will age them a little faster. I prefer to switch mine completely off and if they die, charge them back up when I need them. In the past 5-6 years I think I've had to use a charger 1 or 2X. And the boats have sat for upwards of 2-3 months.