To solve the problem, wherein for charging a rechargeable battery by rotating a generator by the revolution of wheels of a wheelchair that is so slow as to be unsuitable for power generation, at least a voltage of 1.2 V or more must be generated, and that the output power from the generator must be 3.0 V or more that is a practical voltage for operating a device using a dry battery, such as a remote controller.

Since it is necessary to prepare a rotor having a greater number of poles of magnets to generate a high voltage through a low number of revolutions, a stepping motor is used in the generator which is equipped with a voltage amplifying circuit that uses a transformer. When the power generated is output, six rechargeable batteries connected in parallel at power generation are reconnected in series, through a serial/parallel connection switching circuit to output a voltage of 3.0 V or more.