Abstract: The preferred embodiment of the invention disclosed in this application includes a vehicle having an engine and carrying a lift apparatus including a boom assembly and hydraulic motors operatively associated with a hydraulic control system for selectively operating the motors to raise and lower the boom. Included in the hydraulic control system is an electric motor and a pump, the former driving the latter and being energized by an electric power system including battery means in series with the motor. Between the battery and the motor there is provided switch means operatively associated with valve actuating members used for the selective operation of the hydraulic control system so that when any valve actuating member is moved to a position operating the hydraulic control system, it simultaneously actuates the switch means closing the circuit between the battery and the motor.