In an implanted medical device system, an internal controller, external power transmitter and methods for monitoring and dynamically managing power in an implanted medical device system are disclosed. According to one aspect, an internal controller is configured to provide power to a motor of an implanted medical device, the power being drawn from at least one of an internal battery and an internal coil, the at least one of the internal battery and the internal coil providing a supplied voltage. The internal controller includes processing circuitry configured to switch to one of the internal battery, the internal coil and a combination of the internal battery and the internal coil, based on a comparison of the supplied voltage to a threshold.