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A SYSTEM TO RAPIDLY CHARGE DIODE ISOLATED BATTERY OPERATED DEVICES

IP.com Disclosure Number: IPCOM000006967D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2002-Feb-13
Document File: 2 page(s) / 82K

Publishing Venue

Motorola

Related People

Mark Libner: AUTHOR [+2]

Abstract

One method to efficiently and effectively fast charge nickel cadmium and nickel hydride batteries is using multiple cycles which include periods of high forward charge current followed by short discharge pulses. This charging process is sometimes referred to as "burping the battery" or "negative pulse charging? The primary purpose of the discharge pulse is to prevent the accumulation of gas bubbles on the surface of the cell plates which reduces the plate area. Oxygen also causes the internal impedance to go up and causes hot spots to develop on the remaining exposed area. The discharge pulse acts to "burp" the battery by strip- ping the bubbles away from the plates and assist in the recombination of oxygen at the negative plates. The charge/discharge pulse cycling also helps to restore the crystal structure of the cell plates by breaking down crys- tal formations, eliminating "memory" problems.

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0 MOIOROLA INC.

Technical Developments Volume 19 June 1993

A SYSTEM TO RAPIDLY CHARGE DIODE ISOLATED BATTERY OPERATED DWICES

by Mark Libner and Dick Wendt

  One method to efficiently and effectively fast charge nickel cadmium and nickel hydride batteries is using multiple cycles which include periods of high forward charge current followed by short discharge pulses. This charging process is sometimes referred to as "burping the battery" or "negative pulse charging?

  The primary purpose of the discharge pulse is to prevent the accumulation of gas bubbles on the surface of the cell plates which reduces the plate area. Oxygen also causes the internal impedance to go up and causes hot spots to develop on the remaining exposed area. The discharge pulse acts to "burp" the battery by strip- ping the bubbles away from the plates and assist in the recombination of oxygen at the negative plates. The charge/discharge pulse cycling also helps to restore the crystal structure of the cell plates by breaking down crys- tal formations, eliminating "memory" problems.

  Although there are prior systems covering the charge/discharge method of charging nickel cadmium batteries, the use of this charging method has not been incorporated for short circuit protection of the external, end product charging terminals. On most hand held units

the charging terminals are exposed through the back or bottom of the battery case. This allows the end user to place the product into a battery charger without remov- ing the battery pack from the unit. The exposed battery terminals...