Presented herein are techniques for protecting an implantable component of a medical device from the buildup of excessive heat following a charging process. In one embodiment, the implantable component includes a resonant tank circuit that includes an implantable coil that receives power from the external charging device via an inductive link. The implantable component includes a rechargeable battery that is electrically connected to the resonant tank circuit and that can be recharged using the power received from the external charging device. A controller in the implantable component is configured to determine when charging of the rechargeable battery should be terminated and, in response, detune the resonant tank circuit in accordance with a predetermined pattern to signal to the external charging device that charging of the rechargeable battery should be terminated.