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DYNAMIC RADIO LOW VOLTAGE BATTERY THRESHOLD AND CHARGER RADIO ON/OFF RECOGNITION SCHEME

IP.com Disclosure Number: IPCOM000007783D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2002-Apr-23
Document File: 2 page(s) / 122K

Publishing Venue

Motorola

Related People

Joseph PatiƱo: AUTHOR [+4]

Abstract

Today's radios are not able to determine the chemistry type battery connected and as such can not adjust the radio low voltage threshold indicator accordingly. This is especially a problem with new chemistry types such as Li Ion which have a lower and flatter discharge curve than NiCad. The use of the existing NiCad low voltage threshold for a Li Ion battery will cause the radio to prematurely indi- cate low battery. Hence a need exists to allow the radio to dynamically adjust the low voltage thresh- old corresponding to chemistry battery type.

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M-LA Technical Developments

DYNAMIC RADIO LOW VOLTAGE BATTERY THRESHOLD AND CHARGER RADIO ON/OFF RECOGNITION SCHEME

by Joseph Patitio, Patrick Koskan, Thomas Fitzgibbons and Kevin Mayginnes

  Today's radios are not able to determine the chemistry type battery connected and as such can not adjust the radio low voltage threshold indicator accordingly. This is especially a problem with new chemistry types such as Li Ion which have a lower and flatter discharge curve than NiCad. The use of the existing NiCad low voltage threshold for a Li Ion battery will cause the radio to prematurely indi- cate low battery. Hence a need exists to allow the radio to dynamically adjust the low voltage thresh- old corresponding to chemistry battery type.

  In addition, today's chargers trickle charge bat- teries at C/20 for cycle life requirements. If a radio is left on during trickle, the amount ofcurrent being supplied to the charger is actually less than that being drawn from the battery. Hence the battery is actually being discharged. Therefore a need exists to determine the state ofthe radio to allow for stand by current compensation to assure proper battery charging while yet not sacrificing cycle life.

  This invention accomplishes both these capa- bilities by adding a contact to the radio and allow for the charger to selectively switch the pull up resis- tor onto the Rc line. The invention allows for: l-The charger to determine the battery's chemistry/capacity type (Rc) as always, 2-The charger to determine if the radio is on or off to allow for enhanced stand by compensation current capability in a desk top charger, and 3-The radio to determine the battery's chemistry/capacity type to determine the proper low voltage threshold and set it dynamically to allow for optimized low voltage indication performance.

  Refer to "Existing Block diagram" attached. Existing batteries use two battery connections to determine the battery's temperature (Rt) and bat- tery type/capacity (Rc). This is done by reading the resistor divider voltage presented to the corresponding A/D inputs.

Refer to "Proposed Block Diagram" attached.

The radio can determine the proper low voltage threshold by reading the voltage at its A/D4 port on the radio's pp. The voltage is comprised by battery's Rc resistor and radio's pull up resistor R4. This volt- age determines the battery chemistry/capacity type. The voltage read at A/D4 correspond to a unique battery chemistry/capacity type, which is then cross- referenced to a look up table in the radio software where the desired low voltage threshold as deter- mined by the battery chemi...