Method and apparatus for charging a rechargeable battery
First Claim
1. A method of charging a rechargeable battery, the method comprising:
- (a) providing a battery pack comprising;
(1) a plurality of terminals for accepting a charging current, a first voltage being developed across the terminals;
(2) a rechargeable battery, coupled to the terminals, a second voltage being developed across the rechargeable battery, the rechargeable battery operating according to a model comprising;
(A) an ideal battery, a third voltage being developed across the ideal battery, the third voltage reaching an end-of-charge voltage when the rechargeable battery is fully charged, and(B) an internal resistance, a voltage differential between the second voltage and the third voltage being developed across the internal resistance in proportion to the charging current; and
(3) a protection circuit, coupled to the rechargeable battery, for causing charging current to be stopped whenever the second voltage reaches a threshold voltage; and
(b) supplying charging current so as to maintain the second voltage to be above the end-of-charge voltage and to be below the threshold voltage during at least part of the charging process;
whereby the rechargeable battery is charged without the protection circuit causing charging current to be stopped.
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Accused Products
Abstract
In a system and method for charging a rechargeable battery having a protection circuit, the rechargeable battery operates according to a model that includes an ideal battery and an internal resistance. In the model, an electrode voltage develops across the ideal battery. An internal voltage drop equal to the difference between this electrode voltage and the battery voltage is developed across the internal resistance. The battery is charged with a charging voltage that may exceed the threshold voltage and the electrode voltage. The charging system and method ensures that (1) the voltage at the protection circuit is kept below the threshold voltage and (2) the electrode voltage is kept below the end-of-charge voltage.
113 Citations
48 Claims
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1. A method of charging a rechargeable battery, the method comprising:
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(a) providing a battery pack comprising; (1) a plurality of terminals for accepting a charging current, a first voltage being developed across the terminals; (2) a rechargeable battery, coupled to the terminals, a second voltage being developed across the rechargeable battery, the rechargeable battery operating according to a model comprising; (A) an ideal battery, a third voltage being developed across the ideal battery, the third voltage reaching an end-of-charge voltage when the rechargeable battery is fully charged, and (B) an internal resistance, a voltage differential between the second voltage and the third voltage being developed across the internal resistance in proportion to the charging current; and (3) a protection circuit, coupled to the rechargeable battery, for causing charging current to be stopped whenever the second voltage reaches a threshold voltage; and (b) supplying charging current so as to maintain the second voltage to be above the end-of-charge voltage and to be below the threshold voltage during at least part of the charging process; whereby the rechargeable battery is charged without the protection circuit causing charging current to be stopped. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of charging a rechargeable battery, the method comprising, in sequence:
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(a) providing a battery pack comprising; (1) a plurality of terminals for accepting a charging current, a first voltage being developed across the terminals; (2) a rechargeable battery, coupled to the terminals, a second voltage being developed across the rechargeable battery, the rechargeable battery operating according to a model comprising; (A) an ideal battery, a third voltage being developed across the ideal battery, the third voltage reaching an end-of-charge voltage when the rechargeable battery is fully charged, and (B) an internal resistance, a voltage differential between the second voltage and the third voltage being developed across the internal resistance in proportion to the charging current; and (3) a protection circuit, coupled to the rechargeable battery, for causing charging current to be stopped whenever the second voltage reaches a threshold voltage; (b) supplying charging current at a constant current rate of about 1-2 times the amount of current that would charge the rechargeable battery in one hour; (c) supplying charging current so as to maintain the first voltage to be at or below a maximum charging voltage; (d) supplying charging current so as to maintain the second voltage to be above the end-of-charge voltage and to be below the threshold voltage; (e) supplying charging current to maintain the third voltage to be at or below the end-of-charge voltage; and (f) terminating charging when the charging current falls below a lower limit, the lower limit being in the range from about 5% to about 20% of the constant charging current; whereby the rechargeable battery is charged without the first voltage exceeding the maximum charging voltage, the second voltage exceeding the threshold voltage of the protection circuit, or the third voltage exceeding the end-of-charge voltage. - View Dependent Claims (16, 17, 18, 19, 20, 23, 24, 25)
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21. A system for charging a rechargeable battery, the system comprising:
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(a) a battery pack including; (1) a plurality of terminals for accepting a charging current, a first voltage being developed across the terminals; (2) a rechargeable battery, coupled to the terminals, a second voltage being developed across the rechargeable battery, the rechargeable battery operating according to a model comprising; (A) an ideal battery, a third voltage being developed across the ideal battery, the third voltage reaching an end-of-charge voltage when the rechargeable battery is fully charged, and (B) an internal resistance, a voltage differential between the second voltage and the third voltage being developed across the internal resistance in proportion to the charging current; and (3) a protection circuit, coupled to the rechargeable battery, for causing charging current to be stopped whenever the second voltage reaches a threshold voltage; and (b) a charger for supplying charging current in a charging process, the charging process comprising maintaining the second voltage to be above the end-of-charge voltage and to be below the threshold voltage during at least part of the charging process; whereby the charger charges the rechargeable battery without the protection circuit causing charging current to be stopped. - View Dependent Claims (22, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A system for charging a rechargeable battery, the system comprising:
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(a) a battery pack comprising; (1) a plurality of terminals for accepting a charging current, a first voltage being developed across the terminals; (2) a rechargeable battery, coupled to the terminals, a second voltage being developed across the rechargeable battery, the rechargeable battery operating according to a model comprising; (A) an ideal battery, a third voltage being developed across the ideal battery, the third voltage reaching an end-of-charge voltage when the rechargeable battery is fully charged, and (B) an internal resistance, a voltage differential between the second voltage and the third voltage being developed across the internal resistance in proportion to the charging current; and (3) a protection circuit, coupled to the rechargeable battery, for causing charging current to be stopped whenever the second voltage reaches a threshold voltage; (b) a charger for supplying charging current in a charging process, the charging process comprising; (1) supplying a constant charging current at a rate of about 1-2 times the amount of current that would charge the rechargeable battery in one hour; (2) supplying charging current so as to maintain the first voltage to be at or below a maximum charging voltage; (3) supplying charging current so as to maintain the second voltage to be above the end-of-charge voltage and to be below the threshold voltage; (4) supplying charging current to maintain the third voltage to be at or below the end-of-charge voltage; and (5) terminating charging when the charging current falls below a lower limit, the lower limit being in the range from about 5% to about 20% of the constant charging current; whereby the charger charges the rechargeable battery without allowing the first voltage to exceed the maximum charging voltage, without allowing the second voltage to exceed the threshold voltage of the protection circuit, and without allowing the third voltage to exceed the end-of-charge voltage. - View Dependent Claims (36, 37, 38, 39, 40, 41)
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42. A system for charging a rechargeable battery, the system comprising:
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(a) a battery pack including (1) a plurality of terminals for accepting a charging current specified not to exceed a maximum charging current, a first voltage specified not to exceed a maximum charging voltage being developed across the terminals; (2) a rechargeable battery, coupled to the terminals, a second voltage being developed across the rechargeable battery, the rechargeable battery operating according to a model comprising; (A) an ideal battery, a third voltage specified not to exceed an end-of-charge voltage being developed across the ideal battery, the end-of-charge voltage being developed across the ideal battery when the rechargeable battery is fully charged, (B) an internal resistance, a voltage differential between the second voltage and the third voltage being developed across the internal resistance in proportion to the charging current, and (C) an information storage device for storing a plurality of charging parameters; and (b) a battery charger for charging the rechargeable battery, the charger including an information receiver for receiving the charging parameters, the charger controlling the charging of the rechargeable battery in accordance with the plurality of charging parameters. - View Dependent Claims (43, 44, 45, 46, 47, 48)
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Specification