Sounds like you need a little explanation of battery technology. You can wire batteries together for two purposes, these are called series and parallel. Wired Parallel means connecting the positive terminals together and connecting the negative terminals together. With this wiring your voltage stays the same but the amps double. So two 12 volt batteries wired parallel still give off 12 volts but capacity (amps) increase. The other wiring method called Series involves wiring the positive terminal of battery 1 to the negative of battery 2, then wiring the positive of battery 2 to the negative of battery 3. Series multiplies the voltage available. Two 12 volt batteries wired in series give off 24 volts, three batteries in series give off 36 volts. So a 12 volt motor needs one 12 volt battery, a 24 volt motor needs 2 batteries wired in series, and a 36 volt motor needs three batteries wired in series. In addition to these, you need one other seperate battery to crank your motor and run your other 12 volt devices from. So you need a charger that has the same number of banks as the number of batteries you have. Each bank is wired to a specific battery and charges that battery. A multibank charger is actually seperate chargers all contained in a single device. Hope that helps.