I'm upgrading from a 2 bank charger to a 3 bank charger and I'm having issues getting with charging the boat battery. I have 2 trolling motor batteries that charge just fine but it does not appear to be charging the starting battery so I don't know if there is a trick to hooking up to the starting battery. I connected both + and - leads directly to the battery. I do have a cutoff switch so I'm not sure if maybe I should be connecting to the cutoff switch instead of the battery. I would appreciate any tips anyone has to get all 3 banks charging correctly. Thanks.

If it has a fuse check them.

Connect directly to the battery not the cutoff switch. Check the fuse if still not charging return/replace it. Is the starting battery dead, if so it may be ruined and can't take a charge.

read all of your instruction material. some 3 bank chargers put out different amps on each lead, or two will be alike and one will be higher or smaller. you may have the cranking battery hooked to the wrong lead. just a guess----from experience. good luck.

Swap the leads with another bank see if problem follows the lead then problem is with charger. But check as previously suggested. Blown fuse and directly connected to charger.

Thanks for all the comments. i'll be playing with it again in a few days when I'm back at the lake.