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TI develops accurate gas gauge technology for lithium batteries

Posted: 17 Sep 2004 ?? ?Print Version ?Bookmark and Share

Keywords:texas instruments? lithium battery packs? four-cell battery packs?

Texas Instruments Inc. has developed a gas gauge technology the company says calculates remaining capacity in lithium-based battery packs with up to 99 percent accuracy throughout the entire life of a battery.

Called Impedance Track, the technology gauges changes in impedance, or resistance caused by battery age, temperature and cycle patterns, to accurately predict run-time of two-, three- and four-cell battery packs. It enables designers and users of portable medical, industrial appliances and notebooks to prolong battery use and know the exact amount of potential energy left inside the battery, said the company.

The technology uses a dynamic modeling algorithm to learn how much a battery has degraded through age, temperature or usage, and then correlates typical chemical properties of the anode/cathode system in the battery's cell no matter what brand of battery cell used. The algorithm allows different manufacturers' cells to be mixed in a single pack, providing flexibility and continuity of supply.

The technology determines an exact starting position for an instant state of charge, and calculates total capacity from the amount of capacity that exists, eliminating the need for a full charge and discharge cycle.

For applications such as heart defibrillators or back-up battery packs in telecom systems that never fully charge and discharge, Impedance Track will ensure instant and accurate capacity information on a continual basis, according to TI.

The company said the technology saves OEMs and manufacturers time characterizing battery systems because its algorithms do not rely on modeling techniques requiring the creation of large databases in order to measure each attribute of hundreds of available battery parameters.

Texas Instrument is initially implementing Impedance Track inside its Flash-based bq20z8x gas gauge chipset for applications involving multi-cell lithium battery packs. However, the company expects Impedance Track in the future to support nickel-metal hydride (NiMH) and nickel-cadmium (NiCd) batteries, as well as single-cell lithium applications such as smart phones, digital still cameras and PDAs.

- Spencer Chin

EE Times

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