The present invention provides a high current pulse generator for DC powered devices. The generator includes batteries as the power source that charges supercapacitors as well as provides power to the loads as required. During charging, the supercapacitors are connected in parallel, but they are switched to series connection by relays at the moment that the loads demand large currents. No other controlling means except for relays in the circuit is employed, so that the electric arrangement is simple, reliable, and cost-effective. As the batteries are designed to deliver currents at low discharge rates, the effective use-time of batteries is prolonged. Furthermore, due to the high power densities of supercapacitors, the readily available alkaline batteries can be utilized in the power unit for electric power tools.