A military vehicle including an engine coupled to the chassis for providing mechanical power to the military vehicle, a motor/generator coupled to the engine, and an energy storage system including a battery electrically coupled to the motor/generator. The military vehicle is operable in a silent mobility mode with the engine inactive and the energy storage system providing power to the motor/generator to operate the military vehicle. The motor/generator and the battery are sized such that electrical power generation through engine drive of the motor/generator is greater than the power depletion through operation of the military vehicle in the silent mobility mode. The motor/generator can charge the energy storage system while the military vehicle is driving or stationary.