An electrical system control for a vehicle having a charging source, a first battery connected in series with a second battery to form a primary power supply that is connected to the charging source, and a third battery forming a secondary power supply. The system comprises a first bidirectional battery equalizer connected to the charging source and further connected to the second battery, a second bidirectional battery equalizer connected to the charging source and further connected to the third battery, and a controller adapted to monitor the state of at least one of the charging source and the first, second and third batteries. The controller also controls the operation of at least one of the first and second bidirectional battery equalizers in a predetermined manner, effective to control the charge and discharge of at least one of the first, second and third batteries.