Method and apparatus for determining depleted capacity of a battery
First Claim
1. A method for determining depleted capacity of a battery of CFx type used in an implantable medical device, characterized in that average values of battery voltage and current drawn from the battery (2) are measured during a measurement time, the length of which exceeds a battery voltage recovery time after a load change, and in that predetermined relations between, on one hand, combinations of average values of voltage and current and, on the other, depleted battery capacity are used for determining depleted capacity of the battery from said measured average voltage and current.
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Abstract
A method of detecting the status of the battery of an implantable heart stimulator comprises the steps of measuring the impedance of the battery, detecting an increased value of the measured impedance, determining an impedance based value of the remaining capacity of the battery from the detected impedance increase, combined with the steps of measuring the total charge depleted from the battery, and determining a charge depletion based value of the remaining capacity of the battery. A battery status detecting circuit for an implantable heart stimulator includes a first measurement means (12) for measuring the impedance of the battery (6), a detection means (14) for detecting an increased value of the measured impedance, a first determination means (16) for determining an impedance based value of the remaining capacity of the battery from the detected impedance increase. A second measurement means (22) is provided for measuring the total charge depleted from the battery, and a second determination means (24) is provided for determimng a charge depletion based value of the remainig battery capacity.
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Citations
16 Claims
- 1. A method for determining depleted capacity of a battery of CFx type used in an implantable medical device, characterized in that average values of battery voltage and current drawn from the battery (2) are measured during a measurement time, the length of which exceeds a battery voltage recovery time after a load change, and in that predetermined relations between, on one hand, combinations of average values of voltage and current and, on the other, depleted battery capacity are used for determining depleted capacity of the battery from said measured average voltage and current.
- 9. An apparatus for determining depleted capacity of a battery of CFx type used in an implantable medical device, characterized in that averaging means (10,12) are provided to determine average values of battery voltage and current drawn from the battery during a measurement time, the length of which exceeds a battery voltage recovery time after a load change, and in that a determining means is provided for determining actual depleted battery capacity from predetermined relations between, on one hand, combinations of average values of voltage and current and, on the other, depleted battery capacity.
Specification