Which of the following are correct concerning series parallel electrical systems? Other electrical devices using large amounts of power benefit from 24 volts, as their size and the gauge of electrical wire supplying current is smaller. Series parallel electrical systems, or spilt load as it is generally called, use two, four, or six 12-volt batteries connected in series through an equalizer to supply most of the vehicle's electrical systems. All of these are correct. Large engines with high starter torque requirements will use 24-volt starters