Indicator of remaining energy in storage cell of implantable medical device
First Claim
1. A method comprising:
- drawing a substantially constant first current pulse from an energy storage cell during a first time period between a starting time and an ending time;
measuring a first change of a terminal voltage across the cell during the first time period; and
comparing the measured first change to first stored data to determine the energy remaining in the cell.
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Accused Products
Abstract
A manganese dioxide (MnO2) or silver vanadium oxide (SVO) or other battery of an implantable medical device having a relatively flat quiescent battery voltage during a beginning portion of the battery'"'"'s useful life, makes it difficult to use quiescent battery voltage as an indicator of remaining battery energy during this portion of the battery life. A substantially constant load current pulse is drawn from the battery and a pair of loaded battery terminal voltage measurements is taken during this pulse. A difference between the voltage measurements is computed. This difference can be expressed as a rate of change, a slope, or a polarization angle, and can be used with stored data from similar batteries to determine remaining energy of the battery. A quiescent battery voltage can also be used in combination with this technique, and/or for distinguishing between different remaining energies corresponding to the same difference, slope, or polarization angle.
110 Citations
29 Claims
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1. A method comprising:
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drawing a substantially constant first current pulse from an energy storage cell during a first time period between a starting time and an ending time;
measuring a first change of a terminal voltage across the cell during the first time period; and
comparing the measured first change to first stored data to determine the energy remaining in the cell. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method comprising:
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drawing a substantially constant first current pulse from an energy cell during a first time period;
measuring a first change in a terminal voltage across the cell during the first time period;
drawing a substantially constant second current pulse from the cell during a different second time period;
measuring a second change in the terminal voltage across the cell during the second time period; and
comparing the measured second change to first stored data to determine an energy remaining in the cell, including comparing the first and second changes to distinguish between two different stored capacity values that correspond to a single change in the terminal voltage across the cell. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A system comprising:
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an energy storage cell;
a current source/sink circuit, coupled to the cell, to draw a substantially constant first current pulse;
a voltage measurement circuit, coupled to the cell, to measure first and second voltages during the first current pulse;
a difference circuit, coupled to the voltage measurement circuit, to compute a difference between the first and second voltages; and
a processor circuit, coupled to the difference circuit, the processor circuit including a memory circuit to store first data relating cell capacity to the difference between the first and second voltages, the memory circuit also including a cell capacity indicator storage location to provide an indication of cell capacity, the processor configured to use the difference between the first and second voltages obtained from the difference circuit and the stored first data indicative of cell capacity to provide the indication of cell capacity. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification