A power module is configured to provide power to an electronic device. The module includes a rechargeable battery, an electrical generator, and a driving member. The electrical generator includes a rotor. The driving member is used to drive the rotor to rotate, and includes a mainspring, a receiver to receive the mainspring, and a shaft including one end connected to the mainspring and an opposite end connected to the rotor, enabling the rotor to rotate in union with the shaft. A cable includes one end attached to the shaft with a portion of the cable wound around the shaft. When an opposite end of the cable is pulled, the shaft rotates in a first direction, compressing the mainspring, when the mainspring rebounds, the shaft rotates back in a second direction, and the unwound part of the cable is wound back onto the shaft.