Patent ID: 6901293

Claim:
An implantable medical device for delivering a therapeutic output to a patient, comprising: an electrical power source having a useful life and a voltage which declines over said useful life; a therapeutic delivery device operatively coupled to said power source and adapted to deliver said therapeutic output to said patient; and a power source longevity monitor operatively coupled to said power source and said therapeutic delivery device, comprising: an energy counter for counting the amount of energy used by said implantable medical device; an energy converter for converting said energy used into an estimate of remaining power source longevity and generating an energy longevity estimate; a voltage monitor for monitoring said voltage of said power source; a voltage converter for converting said voltage monitored by said voltage monitor into an estimate of remaining longevity of said power source and generating a voltage longevity estimate; and a calculator operatively coupled to said energy converter and to said voltage converter, said calculator predicting said power source longevity using said energy longevity estimate early in said useful life of said power source and using said voltage longevity estimate later in said useful life of said power source.