Patent ID: 6167309
Filing Date: 2000-12-26
Classification: A61N,G01R,H02J

Abstract:
A process for estimating a level of power depletion in a cardiac pacing system having a lithium battery, a first cardiac pacing device electrically connected to said lithium battery and said first cardiac pacing device operating in an episodic manner and powered by said lithium battery, and a charge storage capacitor electrically connected to said lithium battery, said cardiac pacing system having at least one second device attached to said charge storage capacitor, and the second device:a) reads a rate of charge storage within said storage capacitor without disconnecting the electrical connection between said charge storage capacitor and said lithium battery orb) measures both charge added to said charge storage capacitor and a time during which said charge is added to said charge storage capacitor, said measuring of both charge added to said charge storage capacitor and a time during which said charge is added to said charge storage capacitor being performed without disconnecting the electrical connection between said charge storage capacitor and said lithium battery, and calculating a rate of charge storage in said charge storage capacitor,said process comprising the steps of adding charge to said charge storage capacitor from said lithium battery and:i) finding a relatively quiescent period in powering of said first device in said episodic manner,ii) determining a rate of said charge storage in said charge storage capacitor during said relatively quiescent period, andiii) correlating said rate of charging in said charge storage capacitor to a value of internal resistance in said lithium battery to determine a value for the internal resistance of said lithium battery,said internal resistance estimating a level of power depletion in the cardiac pacing system having said lithium battery.