Battery state of charge determination with plural periodic measurements to determine its internal impedance and geometric capacitance
US5369364A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 26, 1993 |
| Grant date | Nov 29, 1994 |
| Priority date | — |
| Expiry date | Apr 26, 2013 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61N1/3708
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for measuring the depletion level (depth of discharge) of a lithium-iodine battery in an implantable medical device. A first set of measurements are made to determine the internal impedance of the battery, and a second set of measurements are made to determine the geometric capacitance of the battery, which has been found to correlate closely to the depth of discharge of the battery. The measurements are all made while the pacemaker is first temporarily decoupled from the medical device circuitry. The first measurements are made during a time window following a known change in resistive load across the terminals of the battery, and are capable of being correlated with 1-kHz qualification testing data made on the battery at the time of manufacture. The second measurements are made when the known load is periodically coupled and decoupled to the terminals of the battery at a rate of 80-kHz. The resulting data can be used to monitor depth of discharge throughout the operable life of the battery.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.