I have a three battery set up for my boat ( 2 for my trolling set up and 1 for the boat obviously )  I bought the boat used and it has a 2 bank charger for the trolling batteries which means I use a small battery tender on my 12 volt when not in use. My question is will a 3 bank charger be the way to go? Maybe a dumb question but this is my first boat and I want to keep the batteries as nice as I can this winter.  Thanks, Lee

yes

a three bank charger is the way to go. It's also worth the effort to climate control your batteries during the winter months. If you park your boat outdoors bring the batteries in during the freeze.