Trolling motor batteries should be recharged as soon as possible after use. They will last much longer if you do that. The starting battery may need to be charged once in a while if you only run the big motor for short periods of time. First step is to determine how the batteries are being used. Usually with 3, one is used for starting and 2 for the trolling motor. Normally the motor just charges the starting battery. Check and be sure the motor is charging. A simple voltage check with the motor off and then compare it with the motor running. You should see a slight increase in voltage at about 1500 rpm. Of course you water to have water hooked up to it if not in the water. So tell us, what did you get?
Fair Winds and Following Seas
Bill H. PTC USN Ret
Chesapeake, Va