Rechargeable battery having overcharge protection circuit and method of charging rechargeable battery
First Claim
1. A rechargeable battery pack for use with a charging adapter having first and second electrical terminals for charging the battery pack, the charging adaptor including means for changing between high and low charging rates in response to a voltage change detected at the first and second contacts, the battery pack comprising:
- at least one rechargeable cell having first and second poles;
a first electrical contact positioned for contacting the first terminal of the charging adapter, said first electrical contact being electrically coupled to said first pole of said rechargeable cell;
a second electrical contact positioned for contacting the second terminal of the charging adapter, said second electrical contact being electrically coupled to said second pole of said rechargeable cell;
a voltage adjusting circuit for increasing the voltage across the first and second electrical contacts upon receipt of a first command and for decreasing the voltage across the first and second electrical contacts upon receipt of a second command;
a timing means for measuring time; and
a control means coupled to said timing means and said voltage adjusting circuit for communicating said first command to said voltage adjusting circuit, and for communicating said second command to said voltage adjusting circuit after a predetermined amount of time.
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Accused Products
Abstract
A rechargeable battery is provided with an overcharge protection circuit which is particularly adapted for nickel metal hydride battery packs to be used in conventional charging adapters suitable for NI-CAD battery packs. The battery pack includes a microprocessor which measures the voltage across the electrical contacts of the battery pack. Upon reaching peak charge, the microprocessor increases the voltage appearing across the battery pack contacts. After a predetermined time period as measured by the microprocessor, the microprocessor decreases the voltage appearing across the battery pack terminals to exceed the change in voltage to which the charging adapter responds to terminate a high rate of charging.
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Citations
17 Claims
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1. A rechargeable battery pack for use with a charging adapter having first and second electrical terminals for charging the battery pack, the charging adaptor including means for changing between high and low charging rates in response to a voltage change detected at the first and second contacts, the battery pack comprising:
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at least one rechargeable cell having first and second poles; a first electrical contact positioned for contacting the first terminal of the charging adapter, said first electrical contact being electrically coupled to said first pole of said rechargeable cell; a second electrical contact positioned for contacting the second terminal of the charging adapter, said second electrical contact being electrically coupled to said second pole of said rechargeable cell; a voltage adjusting circuit for increasing the voltage across the first and second electrical contacts upon receipt of a first command and for decreasing the voltage across the first and second electrical contacts upon receipt of a second command; a timing means for measuring time; and a control means coupled to said timing means and said voltage adjusting circuit for communicating said first command to said voltage adjusting circuit, and for communicating said second command to said voltage adjusting circuit after a predetermined amount of time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of recharging a battery having first and second electrical contacts using a charging adaptor having first and second electrical terminals for charging the battery pack, the charging adaptor including means for changing between high and low charging rates in response to a voltage change detected at the first and second contacts, the charging adapter also being responsive to detect the voltage across the first and second electrical contacts of the battery pack to change between first and second charging rates for charging the battery pack, the method comprising the steps of:
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charging the battery pack at the first charging rate; increasing the voltage across the first and second electrical contacts of the battery pack; measuring the commencement of time after the voltage is increased across the first and second electrical contacts of the battery pack; decreasing the voltage across the first and second electrical contacts of the battery pack a predetermined amount of time after first increasing the voltage appearing across the first and second electrical terminals of the battery pack; and charging the battery pack at the second charging rate in response to the decrease in voltage across the first and second electrical contacts. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification