An uninterruptible power supply system includes power converter circuitry configured to convert AC input power to a first DC power and a second DC power to the first DC power, a battery pack configured to provide the second DC power, a power relay mechanism coupled to the power converter circuitry and to the battery pack that selectively moves between an open position and a closed position, the power relay mechanism coupling the battery pack to the power converter circuitry when in the closed position and isolating the battery pack from the power converter circuitry when in the open position, and control circuitry configured to provide a control signal, where the power relay mechanism includes a motor actuator coupled to the control circuitry, the motor actuator being responsive to the control signal to change the power relay mechanism from the open position to the closed position.