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MAXIMUM CHARGE RATE ALGORITHM FOR PORTABLE BATTERIES

IP.com Disclosure Number: IPCOM000009429D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-22
Document File: 2 page(s) / 85K

Publishing Venue

Motorola

Related People

Joseph PatiƱo: AUTHOR

Abstract

Presently rapid chargers charge batteries at a 1C rate while Ultra fast chargers charge at a fixed rate such as 3C or 4C. Portable batteries have special requirements that do not allow for the Ultra fast charging. This is true because: l- the radio has a maximum input voltage after which the radio trans- mit and receive amplifiers can be damaged, and 2- me portable battery has a reverse discharge protec- tion diode which has a maximum current limit asso- ciated to it. Hence a unique algorithm is needed that allows the battery to be charged in the shortest amount of time while still protecting the radio and battery. This is accomplished by determining the maximum allowable current for the battery based on the diode and by monitoring the battery voltage to assure that the radio maximum input voltage is not exceeded. This invention takes advantage of the existing capabilities of the charger to monitor bat- tery voltage and apply different charge currents and as such requires no new hardware.

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Developments Technical 0 M MOTOROLA

MAXIMUM CHARGE RATE ALGORITHM FOR PORTABLE BATTERIES

by Joseph Patiiio

  Presently rapid chargers charge batteries at a 1C rate while Ultra fast chargers charge at a fixed rate such as 3C or 4C. Portable batteries have special requirements that do not allow for the Ultra fast charging. This is true because: l- the radio has a maximum input voltage after which the radio trans- mit and receive amplifiers can be damaged, and 2- me portable battery has a reverse discharge protec- tion diode which has a maximum current limit asso- ciated to it. Hence a unique algorithm is needed that allows the battery to be charged in the shortest amount of time while still protecting the radio and battery. This is accomplished by determining the maximum allowable current for the battery based on the diode and by monitoring the battery voltage to assure that the radio maximum input voltage is not exceeded. This invention takes advantage of the existing capabilities of the charger to monitor bat- tery voltage and apply different charge currents and as such requires no new hardware.

  Refer to existing and proposed flowcharts on next page. Present day rapid chargers apply a 1C rate to the battery while present day ultra fast charg- ers apply a fixed 3C or 4C rate. What is needed is a hybrid charger that allows for the maximum charge current (Imax = diode current rating) allowable to

the battery without exceeding its reverse protection diode rating. This...