Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells – With discharge of cells or batteries
Patent
1994-10-31
1996-07-23
Wong, Peter S.
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
With discharge of cells or batteries
320 5, H02J 706
Patent
active
055392997
ABSTRACT:
A battery pack 12 for powering a device 14 sensitive to input voltage contains a protection switch 28 and a control circuit 26. When the battery pack 12 is charged by a charger 10 and the voltage of the battery pack approaches the maximum safe level of the device 14, the control circuit 26 causes the protection switch 28 to electrically switch open to protect the device 14 from excessive voltage potentially output by the charger. Where the cells 16 are lithium ion cells or a type having a maximum safe voltage, a safety switch 49 is included to interrupt charge current 52 through the cells 16. The safety switch 49 is delayed by resistor/capacitor network 51, 53 so that it switches after the protection switch 28. The safety switch 49 includes a diode 58 to allow the device 14 to remain powered while the safety switch is blocking charge current. Further, diodes 40 and 42 are required to eliminate measurement error of the control circuit 26 if the battery pack 12 is charged through the device contacts 20 and 24.
REFERENCES:
patent: 4291266 (1981-09-01), Portmann
patent: 5039928 (1991-08-01), Nishi et al.
patent: 5371456 (1994-12-01), Brainard
patent: 5402056 (1995-03-01), Ketterling
patent: 5471128 (1995-11-01), Patino et al.
patent: 5477124 (1995-12-01), Tamai
Fernandez Jose M.
Garrett Scott M.
Meadows Vernon
Garrett Scott M.
Law Patrick B.
Massaroni Kenneth M.
Motorola Inc.
Wong Peter S.
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