Method for monitoring end of life for battery
First Claim
1. A pacemaker, including:
- a battery power terminal for a pacemaker battery;
a capacitor electrically connected to the battery power terminal;
pacemaker control circuitry electrically connected to the battery power terminal and the capacitor for controlling current flow from the battery power terminal to the capacitor to charge the capacitor and to discharge the capacitor to a discharge voltage level (Vd) before beginning a time charge measurement; and
charge time measurement (CTM) control circuitry electrically connected to the pacemaker control circuitry and adapted to;
access a predetermined set of charge time measurement set-up parameters and a predetermined elective replacement time (ERT) charge time limit associated with an AC impedance target for the battery;
determine a rate of charge storage in the capacitor using the predetermined set of charge time measurement set-up parameters; and
declare an ERT using the determined rate of charge storage in the capacitor and the ERT charge time limit,wherein the predetermined set of charge time measurement set-up parameters to be accessed by the CTM control circuitry include;
a final capacitor voltage (VF) to end the charge time measurement for determining the rate of charge storage in the capacitor; and
an initial capacitor reference voltage (VI) to begin the charge time measurement for determining the rate of charge storage in the capacitor, VI being greater than Vd.
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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
20 Claims
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1. A pacemaker, including:
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a battery power terminal for a pacemaker battery; a capacitor electrically connected to the battery power terminal; pacemaker control circuitry electrically connected to the battery power terminal and the capacitor for controlling current flow from the battery power terminal to the capacitor to charge the capacitor and to discharge the capacitor to a discharge voltage level (Vd) before beginning a time charge measurement; and charge time measurement (CTM) control circuitry electrically connected to the pacemaker control circuitry and adapted to; access a predetermined set of charge time measurement set-up parameters and a predetermined elective replacement time (ERT) charge time limit associated with an AC impedance target for the battery; determine a rate of charge storage in the capacitor using the predetermined set of charge time measurement set-up parameters; and declare an ERT using the determined rate of charge storage in the capacitor and the ERT charge time limit, wherein the predetermined set of charge time measurement set-up parameters to be accessed by the CTM control circuitry include; a final capacitor voltage (VF) to end the charge time measurement for determining the rate of charge storage in the capacitor; and an initial capacitor reference voltage (VI) to begin the charge time measurement for determining the rate of charge storage in the capacitor, VI being greater than Vd. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A system, comprising:
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a battery power terminal for a battery; a capacitor electrically connected to the battery power terminal; means to control current flow from the battery power terminal to charge the capacitor; means to access a predetermined set of charge time measurement set-up parameters and a predetermined elective replacement time (ERT) charge time limit associated with an AC impedance target for the battery, the predetermined set of charge time measurement set-up parameters including; a charged capacitor voltage reference (VF) to end a charge time measurement for determining the rate of charge storage in the capacitor; an initial capacitor voltage reference (VI) to begin the charge time measurement for determining the rate of charge storage in the capacitor; and a discharge voltage reference (Vd) to which the capacitor is discharged prior to beginning the time measurement for determining the rate of charge storage in the capacitor, Vd being less than VI; means to determine a rate of charge storage in the capacitor using the predetermined set of charge time measurement set-up parameters; means to compare the determined rate of charge storage in the capacitor to the predetermined ERT charge time limit for the predetermined set of charge time measurement set-up parameters; and means to declare an ERT based on a number of comparisons between the determined rate of charge storage in the capacitor and the ERT charge time limit. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification