Seems like he could use a 2 bank 12V and hook up both leads . Just saw the other day the new Lowrance TM has a switch that can take it from 24V to 36V , depending on how many batteries you want to use .
I just bought a small riverboat and it has big,new battery for the trolling motor.
I think I misread it as 24 volt,but that is the battery class,not the voltage.
My mistake...thanks for the replies,anyway.