apparatus for applying energy to the outside of the skin for penetrating the skin , a transducer for converting the energy penetrating the skin to a form of energy utilizable by a device implanted in the body , and a member for transmitting the skin penetrating energy to the transducer . preferably the applied energy is infrared light or heat with the transmitting member being optical fibers or a heat pipe , respectively , and the implanted device is a pacemaker for the heart , the battery of the pacemaker being rechargeable by the converted energy and the pulse generator of the pacemaker being controllable by the converted energy .