Method for monitoring end of life for battery
First Claim
1. 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.
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Accused Products
Abstract
A system is described which has a battery, a device which is powered by the battery in an episodic manner, and a charge storage capacitor. The system has attached to the 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 the charge storage capacitor so that a rate of charge storage may be calculated. The estimated replacement time for the battery, particularly for a lithium battery in a pacing device, is easily estimated. Also described herein is a process for estimating a level of energy depletion in the system. The process comprises: finding a relatively quiescent period in powering of the device in the episodic manner; determining a rate of charging in the storage capacitor during the quiescent period; and correlating the rate of charging in the storage capacitor to a value of internal impedance in the battery through a comparison with known relationships for the battery and rate of charging to determine a value for the internal impedance of the battery.
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Citations
36 Claims
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1. 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:
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reading the rate of charge storage;
ormeasuring 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A process for estimating a level of energy depletion in a system having a battery, a device powered by said 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:
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reading the rate of charge storage;
ormeasuring 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 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
correlating said rate of charging in said storage capacitor to a value of internal resistance in said battery through a comparison with known relationships for said battery and rate of charging and determining a value for the internal resistance of said battery. - View Dependent Claims (17, 18)
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19. 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 a charge storage capacitor electrically connected to said lithium battery, said first cardiac pacing device operating in an episodic matter and powered by said lithium battery, said cardiac pacing system having at least one second device attached to said charge storage capacitor, and the second device:
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reads a rate of charge storage within said storage capacitor without disconnecting the electrical connection between said charge storage capacitor and said lithium battery;
ormeasures both charge added to said charge storage capacitor and a time when said charge is added to said charge storage capacitor, said measuring of both charge added to said charge storage capacitor and a time when 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; finding a relatively quiescent period in of said first device in said episodic manner;
determining a rate of said charge storage in said charge storage capacitor during said relatively 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
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 impedance of said lithium battery, said internal impedance being used to estimate a level of energy depletion in the cardiac pacing system having said lithium battery. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A process for estimating a level of energy depletion in a battery in a system having a lithium battery, a first device operating in an episodic manner electrically connected to and powered by said lithium battery, and a charge storage capacitor electrically connected to said lithium battery, said system having at least one second device attached to said charge storage capacitor to determine a rate of charging of said charge storage capacitor, and the process comprising said at least one second device:
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reading the rate of charging of said charge storage capacitor;
ormeasuring both charge added to said charge storage capacitor and a time when said charge is added to said charge storage capacitor, said measuring of both charge added to said charge storage capacitor and a time when 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 said rate of charging, said process further comprising the steps of adding charge to said charge storage capacitor from said lithium battery and; finding a relatively quiescent period in powering of said first device in said episodic manner;
determining said rate of charging in said charge storage capacitor during said relatively 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;
correlating said rate of charging in said charge storage capacitor to a value of internal impedance in said lithium battery to determine a value for internal impedance of said battery; and
comparing said value for internal impedance of said lithium battery with known relationships between said internal impedance of said lithium battery and depleted charge from said lithium battery to estimate the level of depletion of said lithium battery. - View Dependent Claims (35, 36)
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Specification