Step 7: Powering the Motor Control System
The motors will be powered by either one or two 12V lead acid battery(ies) OR buy two 6V batteries. The battery(ies) that you buy must be able to provide at least 20AH each. If you decide to go with two 12V batteries you wire the batteries in parallel, if they are two 6V batteries then you wire them in series. If its only one 12V battery then obviously you just directly connect wires to the battey without any hitch.
The relays need their own separate supply of 12V to actuate them . The relays will be actuated by the the main 12 volt power supply of the motors. The reason we can't connect them directly to the computer switching circuit ( we will deal with that in the next step) is because that circuit can only handle 4 amps , and our motors draw 11 amps each . The relays draw less than 4 amps and can therefore control the motors easily.