Overcharge current protection circuit and battery pack using same
First Claim
1. A battery pack for use with a charger having a charge current level and providing a first charge current level in excess of an optimum charge current level and switchable to a second charge current level not exceeding said optimum charge current level upon indication of said battery pack reaching an undesirable temperature, said battery pack having a positive and a negative charging terminal, said battery pack comprising:
- at least one battery cell through which charge current flows;
a temperature sensing element for sensing the temperature of said at least one battery cell and providing a signal to said charger indicating said temperature;
temperature signal switch means coupled parallel with said temperature sensing element for simulating an undesirable battery temperature to said charger when actuated; and
temperature signal switch control means for sensing said charge current level and actuating said temperature signal switch means when said charge current level exceeds an optimum charge current level.
4 Assignments
0 Petitions
Accused Products
Abstract
A battery pack (62) comprises cells (74), and is charged by a charger (64) providing a current level. The charger (64) is a typical nickel-cadmium battery charger providing a first charge current level in excess of an optimum charge current level. The battery pack (62) further comprises a thermal sensing element (76) and an overcurrent charge protection circuit having an overcurrent switch (78), current sense circuit (80), comparator circuit (82), and temperature signal switch (84). If the current level through the cells (74) exceeds the optimum charge current level, the current sense circuit (80) provides a signal to comparator circuit (82) which actuates the temperature signal switch (84), simulating a hot battery pack. The charger (64) then switches to a second charge current level which does not exceed the optimum charge current level. If the charger (64) does not change current levels, a switch delay (86), after a brief period, accumulates enough voltage to actuate a driver switch (88) which opens the overcurrent switch (78), disconnecting the cells (74) from the charger (64).
45 Citations
26 Claims
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1. A battery pack for use with a charger having a charge current level and providing a first charge current level in excess of an optimum charge current level and switchable to a second charge current level not exceeding said optimum charge current level upon indication of said battery pack reaching an undesirable temperature, said battery pack having a positive and a negative charging terminal, said battery pack comprising:
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at least one battery cell through which charge current flows; a temperature sensing element for sensing the temperature of said at least one battery cell and providing a signal to said charger indicating said temperature; temperature signal switch means coupled parallel with said temperature sensing element for simulating an undesirable battery temperature to said charger when actuated; and temperature signal switch control means for sensing said charge current level and actuating said temperature signal switch means when said charge current level exceeds an optimum charge current level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An overcharge current protection circuit for a battery pack having at least one battery cell for use with a charger having a charge current level and providing a first charge current level in excess of an optimum charge current level and switchable to a second charge current level not exceeding said optimum charge current level upon indication of said battery pack reaching an undesirable temperature, said battery pack having a positive and a negative charging terminal, said circuit comprising:
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a temperature sensing element for sensing the temperature of said at least one battery cell and providing a signal to said charger indicating said temperature; temperature signal switch means coupled parallel with said temperature sensing element for simulating an undesirable battery temperature to said charger when actuated; and temperature signal switch control means for sensing said charge current level and actuating said temperature signal switch means when said charge current level exceeds an optimum charge current level. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification