Battery Charger Question

I have a Guest 2 bank battery charger that i no longer use off of one of my boats, i went to a 24 volt trolling motor and had to go with a 3 bank charger.

So my question is can i take the 2 bank battery charger and use both of the 12 volt leads on one 12 volt battery on my small boat, the charger is 2 bank 10 amp on each bank, i noticed when i used only one of the banks the lights on the charger would not work right, and will this charge the battery at 20 amp rate.

Thank in advance
Speck

Yes to all your questions, for the most part. You can hook both to a single battery. You'll get most of the benefit of the 20A rate, although one bank will probably shut down a little earlier than the other. It won't be enough to notice.