Patent ID: 6631293
Filing Date: 2003-10-07
Classification: A61N,G01R,H02J

Abstract:
A process for estimating a level of power depletion in a system having a lithium battery, a cardiac pacing device powered by said lithium battery in an episodic manner, and a charge storage capacitor, said system having attached to said charge storage capacitor a device or devices capable of:reading the rate of charge storage; or measuring both time and charge stored or added to said charge storage capacitor and calculating a rate of charge storage, said process comprising: finding a relatively quiescent period in powering of said cardiac pacing device in said episodic manner; determining a rate of charging in said storage capacitor during said quiescent period, including determining said rate of charging over a time period beginning when the capacitor is not fully discharged and has a predetermined minimum charge differential across the capacitor so that the storage capacitor is discharged to at least said predetermined minimum upon initiation of an episodic charging event; and determining a value for an internal impedance of said battery using known relationships with respect to said rate of charging for said battery.