One embodiment of a power management system includes a reservoir configured to collect energy. The system also includes a voltage regulator coupled to the reservoir via an input terminal and configured to convert the energy to an output voltage via an output terminal when enabled. A threshold detector is coupled to the reservoir and is configured to sense the energy and enable the voltage regulator when the energy exceeds a threshold. The system further includes a feedback circuit coupled between the output terminal and the threshold detector, and configured to feedback the output voltage to the threshold detector to compensate for a voltage drop across the threshold detector due to an output current drawn by the load.