Charging or recharging a capacitor powers a USB key. The capacitor is connected to the USB plug. Inserting the key in a powered device charges or recharges the capacitor. Alternatively, the capacitor is connected to the USB plug and a rotatable generator electrically is connected to the capacitor. A sliding gear having teeth engages with complimentary teeth of the generator. A spring disposed at each end of the sliding gear to restrain the sliding movement of the gear. Movement of the sliding gear kinetically charges or recharges the capacitor. The USB key can include the capacitor alone or the kinetic arrangement or the combination of the capacitor and the kinetic arrangement.