How should a trickle-charger be used on a dual battery setup?

[kaulbr]

This winter I had a second battery and switch installed on my boat so that I could listen to tunes while anchored without worrying about killing my battery. I typically put a trickle-charger on my boat when not in use to keep the batteries fully charged. I'm just wondering how I should do that now that there are two batteries? Just charge one and it'll charge the other?

 

[alldodge]

I would disconnect (battery switch's) bats from each other and everything except 2 separate maintenance charges. Other opinions will be along shortly

 

[dingbat]

Trickle chargers in the scheme of day to day operation are pretty useless. They are designed to compensation for small, self discard rates during long term battery storage.

They should not be used (in an attempt) to charge a battery or compensate for parasitic drains.

Having said that, if you need to charge the batteries between outing get a really battery charger. At that point you could combine both batteries at the switch (both) and connect the charger to one or the other batteries. Or....you could turn switch to off and charge each battery individually.

Ultimately, you may want to install an “add a battery” kit with an ACR. Turn the switch on when you get in the boat, turn it off when you leave.