A power management system is disclosed. Embodiments of the power management system may be configured for use with an electric generator that produces AC or DC voltage from an energy source, which may be intermittent or fluctuating. One embodiment of the power management system includes an energy storage reservoir configured to be electrically coupled to the electric generator. The energy storage reservoir includes at least one ultracapacitor and at least one rechargeable battery. The power management system also includes an electronic controller configured to control storage in the reservoir of energy generated by the electric generator and to control power usage from the reservoir and the generator. The electronic controller is configured to control energy storage and power usage in response to one or more control signals.