Abstract: A power energy supply system includes a power generating device, at least one ultracapacitor, and an electronic control module (ECM) for supplying power energy to electric loads coupled to a vehicle circuit system under control of the ECM. The ECM includes a reference voltage value, a voltage-boosting circuit, and a voltage-stabilizing circuit. When the output voltage supplied from the ultracapacitor is smaller than the reference voltage value, the output voltage of the ultracapacitor is boosted by the voltage-boosting circuit and regulated by the voltage-stabilizing circuit before being supplied to the electric loads of the vehicle circuit system. And, when the output voltage from the ultracapacitor is larger than or equal to the reference voltage value, the output voltage of the ultracapacitor is regulated by the voltage-stabilizing circuit before being supplied to the electric loads of the vehicle circuit system.