A modular battery and power control system provides a range of electrical power to high voltage and low voltage power demand systems in a hybrid vehicle. The modular battery and power control system provides a dual voltage modular battery pack that provides both a high voltage output and a low voltage output. The modular battery pack is selectively connected to high voltage and low voltage demand systems by a switch system. The switch system is controlled by an ignition switch module which determines the electrical demands of the hybrid vehicle.