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THERMAL COMPENSATION CIRCUITS FOR ENHANCED BATTERY PERFORMANCE IN HOSTILE ENVIRONMENTS

IP.com Disclosure Number: IPCOM000006295D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2001-Dec-21
Document File: 1 page(s) / 72K

Publishing Venue

Motorola

Related People

Adnan Aksoy: AUTHOR [+2]

Abstract

The battery charging methods used by many prod- ucts employ a temperature sensing circuit to disable the charge current if batteries are extremely hot or cold. The present specifications allow for charging only in the temperature range of +S"C to +45"C. This invention utilizes a circuit internal to the battery which extends the charging temperature range beyond those normally spec- itied, while utilizing existing chargers in the field with- out catastrophic damage to either battery or charger.

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MOTOROLA INC. Technical Developments Volume 14 December1991

THERMAL COMPENSATION CIRCUITS FOR ENHANCED BATTERY PERFORMANCE IN HOSTILE ENVIRONMENTS

by Adnan Aksoy and Niko M. Savovic -

  The battery charging methods used by many prod- ucts employ a temperature sensing circuit to disable the charge current if batteries are extremely hot or cold. The present specifications allow for charging only in the temperature range of +S"C to +45"C. This invention utilizes a circuit internal to the battery which extends the charging temperature range beyond those normally spec- itied, while utilizing existing chargers in the field with- out catastrophic damage to either battery or charger.

  This invention utilizes placement of a heating ele- ment in conjunction with circuitry inside the battery to warm the energy cells to a suitable temperature before charging in ambient temperature below +S". This proc- ess is totally transparent to the charger, but total charge time will be increased due the warming cycle prior to charge. A resistor RI and a thermostat TI, connected in parallel to the existing thermistor Rthermistor, will lower circuit resistance and enable the charge current to flow. A thermostat Tz is open at cold temperatures, causing the charge current to flow through heating ele- ment HE, in series with thermostat Tz, which gener- ates heat to warm the battery. Once the predetermined temperature is reached, TI and T, open, and T2 closes, allowing all current to flow through the cell pack to charge the battery and returning the thermistory cir- cuitry to...