Electricity: battery or capacitor charging or discharging – Parallel connected batteries
Reexamination Certificate
1999-02-17
2001-07-24
Wong, Peter S. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Parallel connected batteries
C320S128000
Reexamination Certificate
active
06265847
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a control device to control charging and discharging of rechargeable cells for a battery operated device which consumes power from the cells.
BACKGROUND
Rechargeable batteries are commonly used in electrical appliances such as mobile phones, electric shavers and portable music systems. It is well known that to maximise battery performance and to prolong the life of the battery, as measured by the number of charge/discharge cycles, that the battery must be fully discharged before being fully charged. However, for convenience, it is preferable to keep the battery in a state of constant readiness, that is, always fully charged. Therefore, it is common practice to charge a partially drained battery. This causes the battery performance to deteriorate, and the battery is said to exhibit a “memory effect”.
SUMMARY OF THE INVENTION
The present invention seeks to prevent the deterioration of rechargeable batteries due to improper charging.
According to the present invention there is provided a battery charge/discharge control system comprising a battery operated device, to be driven by a discharge current from a rechargeable cell, and a battery control device, to control charging and discharging of rechargeable cells, comprising charging control circuitry to select a discharged cell and permit charging of said cell to a maximum charging level, and discharging control circuitry to select a partially charged cell and permit it to discharge so as to drive the battery operated device, and permit it to discharge to a discharged level.
The system may include measuring circuitry to measure the level of charging of a cell. The measuring circuitry may be a voltmeter.
Accordingly, the system may comprise a comparator to compare levels of charging of cells.
Preferably, the system includes switching circuitry to switch between the cells.
According to the present invention, there is provided a method of controlling charging and discharging battery cells that drive a battery operated device comprising selecting a discharged cell and permitting charging of said cell to a maximum charging level and selecting a partially charged cell and permitting it to discharge so as to drive the battery operated device and permitting it to discharge to a discharge level, prior to recharging.
Thus, only full charging and discharging of the battery cells are performed which maximises their lifetime.
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Standards Coordinating Committee 10, Terms and Definitions, Jane Radatz, Chair, “the IEEE Standard Dictionary of Electrical and Electronics Terms,” pp. 82 and 141.
ICO Services Ltd.
McDermott & Will & Emery
Toatley , Jr. Gregory J.
Wong Peter S.
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