Battery charge indicator such as for an implantable medical device
First Claim
1. A method comprising:
- measuring a first battery voltage of a first battery that is connected to an actual load impedance;
calculating the actual load impedance;
if the actual load impedance differs from a characterizing test load impedance for which capacity vs. voltage characterizing battery data was obtained for a second battery, then computing a translation between the first battery voltage and voltages in the capacity vs. voltage characterizing data for the second battery, the computing the translation including using a logarithmic ratio of the characterizing test load impedance and the actual load impedance; and
computing a corresponding battery capacity of the first battery, using the translation and the capacity vs. voltage characterizing data for the second battery.
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Abstract
This document discusses, among other things, a system providing a battery charge indicator for an implantable medical device, such as using a lithium/carbon monofluoride (CFx) or other battery. Capacity vs. voltage data from a separate characterizing battery into a characterizing load impedance is stored in memory, such as in a lookup table or as a regression equation fitted to the data. For the actual battery of interest, then, a battery terminal voltage and a corresponding load current are measured, and a load impedance is calculated. A translation is performed to make the measured battery voltage and the characterizing capacity vs. voltage data comparable, so that a capacity reading can be obtained.
149 Citations
43 Claims
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1. A method comprising:
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measuring a first battery voltage of a first battery that is connected to an actual load impedance;
calculating the actual load impedance;
if the actual load impedance differs from a characterizing test load impedance for which capacity vs. voltage characterizing battery data was obtained for a second battery, then computing a translation between the first battery voltage and voltages in the capacity vs. voltage characterizing data for the second battery, the computing the translation including using a logarithmic ratio of the characterizing test load impedance and the actual load impedance; and
computing a corresponding battery capacity of the first battery, using the translation and the capacity vs. voltage characterizing data for the second battery. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A system comprising:
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a load impedance;
an implantable first battery, coupled to the load impedance;
a battery terminal voltage measurement circuit, coupled to the first battery to measure a first battery voltage;
a load impedance measurement circuit, coupled to the load impedance to measure an actual load impedance; and
a processor circuit, communicatively coupled to the battery terminal voltage measurement circuit and the load impedance measurement circuit, the processor associated with a separate or integral memory circuit to store capacity vs. voltage characterizing data obtained from a second battery under a characterizing test load impedance, the processor including instructions to compute a translation between the first battery voltage and voltages in the capacity vs. voltage characterizing data for the second battery, including using a logarithmic ratio of the characterizing test load impedance and the actual load impedance, and using the translation to compute a corresponding battery capacity of the first battery using the capacity vs. voltage characterizing data for the second battery. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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Specification