Abstract: A spring power device is provided which includes a multiturn coil spring having its inner end anchored to a rotatable shaft and its outer end anchored to a large drive gear which is mounted to rotate freely on the shaft. An electric motor is connected to rotate the shaft. Whenever the coil spring winds down, a microswitch senses the radial outward movement of the outermost turn thereof and connects a battery to energize the motor to wind up the inner end of the coil spring at a fast rate. The drive gear is controlled to release the power stored in the coil spring to drive a load.