Power source longevity monitor for an implantable medical device. An energy
counter counts the amount of energy used by the implantable medical device. An
energy converter converts the energy used into an estimate of remaining power source
longevity and generating an energy longevity estimate. A voltage monitor monitors
the voltage of the power source. A voltage converter converts the voltage monitored
by the voltage monitor into an estimate of remaining longevity of the power source
and generating a voltage longevity estimate. A calculator is operatively coupled
to the energy converter and to the voltage converter and predicts the power source
longevity using the energy longevity estimate early in the useful life of the power
source and using the voltage longevity estimate later in the useful life of the
power source.
