Method for monitoring end of life for battery
First Claim
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1. A system comprising:
- a lithium battery having an internal resistance;
a charge storage capacitor electrically connected to the lithium battery;
a first device electrically connected to the lithium battery and adapted to be powered by the battery; and
at least one second device electrically connected to said charge storage capacitor,wherein the at least one second device is adapted to perform a charge time measurement, the at least one second device being adapted to;
access a predetermined set of charge time measurement set-up parameters and a predetermined elective replacement time (ERT) charge time limit determined from a battery resistance ERT target that corresponds to a battery charge depletion target wherein the predetermined set of charge time measurement set-up parameters include;
an initial reference voltage (VI) to begin the time measurement for determining the rate of charge storage in the capacitor, VI being larger than a discharge voltage for the capacitor (Vd); and
a physician-programmed final voltage (VF) to end a time measurement for determining the rate of charge storage in the capacitor;
determine a rate of charge storage in the capacitor when the capacitor is charged from VI to VF;
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
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.
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Abstract
A system is described. The system includes a lithium battery, a charge storage capacitor electrically connected to the lithium battery, a first device, and at least one second device. The first device is electrically connected to the lithium battery and is powered by the lithium battery. The at least one second device is attached to the charge storage capacitor and adapted to read a rate of charge storage in the charge storage capacitor or to calculate the rate of charge storage by measuring both a time of charging and a charge stored or added to the charge storage capacitor during the time of charging.
249 Citations
20 Claims
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1. A system comprising:
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a lithium battery having an internal resistance; a charge storage capacitor electrically connected to the lithium battery; a first device electrically connected to the lithium battery and adapted to be powered by the battery; and at least one second device electrically connected to said charge storage capacitor, wherein the at least one second device is adapted to perform a charge time measurement, the at least one second device being adapted to; access a predetermined set of charge time measurement set-up parameters and a predetermined elective replacement time (ERT) charge time limit determined from a battery resistance ERT target that corresponds to a battery charge depletion target wherein the predetermined set of charge time measurement set-up parameters include; an initial reference voltage (VI) to begin the time measurement for determining the rate of charge storage in the capacitor, VI being larger than a discharge voltage for the capacitor (Vd); and a physician-programmed final voltage (VF) to end a time measurement for determining the rate of charge storage in the capacitor; determine a rate of charge storage in the capacitor when the capacitor is charged from VI to VF; 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 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 (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system comprising:
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a lithium battery having an internal resistance; a charge storage capacitor electrically connected to at least the lithium battery; a first device electrically connected to said lithium battery and adapted to be powered by the battery and to select a discharge voltage (Vd); at least one second device electrically connected to said charge storage capacitor, wherein the at least one second device includes; a comparison circuit, wherein the comparison circuitry includes;
a first comparator electrically connected to the lithium battery andadapted for comparing a battery terminal voltage (Vbatt) to a brownout voltage (Vstop), the first comparator having a first comparator output; and a second comparator electrically connected to the charge storage capacitor and adapted for comparing a storage voltage (Vcs) to at least one reference voltage (Vx), the second comparator having a second comparator output, wherein the first comparator output and the second comparator output are adapted to control current flow from the battery power terminal to the charge storage capacitor, and a charge time measurement (CTM) control circuit connected to the comparison circuit to perform a charge time measurement, wherein the charge time measurement (CTM) control circuitry is adapted to; access a predetermined set of charge time measurement set-up parameters and a predetermined elective replacement time (ERT) charge time limit determined from a battery resistance ERT target that corresponds to a battery charge depletion target; determine a rate of charge storage in the capacitor using the predetermined set of charge time measurement set-up parameters, 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 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 (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification