Method and apparatus for determining when to terminate charging of a battery
First Claim
1. A method for charging a battery comprising the steps of:
- generating repetitive charging cycles having charging and multiple depolarization pulses and including at least two rest periods during which there is neither a charge nor a discharge current;
measuring the open circuit voltage of the battery during at least an extended second or later rest period of charge cycles separated in time;
comparing measured open circuit voltages; and
terminating the charging cycles when the comparison step yields a negative change in the open circuit voltage in excess of a predetermined amount.
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Abstract
An apparatus and method for charging a battery are described in a technique wherein charge pulses are followed by discharge pulses and then first rest periods and other discharge pulses followed by second rest periods. Selected ones of the second rest periods are extended in time to enable a battery equilibrium to be established and the open circuit voltage of the battery to settle down and reflect an overcharging condition of the battery. By comparing the open circuit voltages measured during different extended second rest periods small voltage decreases can be reliably detected and used to determine an overcharging condition such as when gases are generated and affect the open circuit voltage. Once overcharging is detected the battery charging is stopped.
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Citations
33 Claims
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1. A method for charging a battery comprising the steps of:
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generating repetitive charging cycles having charging and multiple depolarization pulses and including at least two rest periods during which there is neither a charge nor a discharge current; measuring the open circuit voltage of the battery during at least an extended second or later rest period of charge cycles separated in time; comparing measured open circuit voltages; and terminating the charging cycles when the comparison step yields a negative change in the open circuit voltage in excess of a predetermined amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for charging a battery comprising the steps of:
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generating repetitive charging cycles having charging and single depolarization pulses and including single rest periods during which there is neither a charge nor a discharge current; measuring the open circuit voltage of the battery during an extended single rest period of charge cycles separated in time and at times in the rest period when the battery is in a state of equilibrium; comparing measured open circuit voltages; and terminating the charging cycles when the comparison step yields a negative change in the open circuit voltage in excess of a predetermined amount. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A method for charging a battery comprising the steps of:
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generating repetitive charging cycles having charging and multiple depolarization pulses and including at least two rest periods during which there is neither a charge nor a discharge current; measuring the open circuit voltage of the battery during at least an extended second or later rest period of charge cycles separated in time and at a time when the battery is in a state of equilibrium; comparing measured open circuit voltages; reducing the average charging current when the comparison step fails to yield a drop in the measured open circuit voltage; and terminating the charging cycles when the comparison step yields a negative change in the open circuit voltage. - View Dependent Claims (21, 22, 23, 24)
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25. A method for charging a battery comprising the steps of:
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generating repetitive charging cycles having charging and single depolarization pulses and including single rest periods during which there is neither a charge nor a discharge current; measuring the open circuit voltage of the battery during the rest periods of charge cycles separated in time and at a time when the battery is in a state of equilibrium; comparing measured open circuit voltages; reducing the average charging current when the comparison step fails to yield a drop in the measured open circuit voltage; and terminating the charging cycles when the comparison step yields a negative change in the open circuit voltage. - View Dependent Claims (26, 27, 28, 29)
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30. An apparatus for charging a battery comprising the steps of:
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means for forming repetitive charging cycles having charging and depolarization pulses and including at least two rest periods during which there is neither a charge nor a discharge current; means for measuring the open circuit voltage of the battery during at least the second or later rest period of charge cycles separated in time; means for comparing measured open circuit voltages; and means for terminating the charging cycles when the comparison step yields a negative change in the open circuit voltage in excess of a predetermined amount.
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31. An apparatus for charging a battery comprising the steps of:
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means for forming repetitive charging cycles having charging and single depolarization pulses and including single extended rest periods during which there is neither a charge nor a discharge current; means for measuring the open circuit voltage of the battery during the rest period of charge cycles separated in time and at times in the rest period when the battery is in a state of equilibrium; means for comparing measured open circuit voltages; and means for terminating the charging cycles when the comparison step yields a negative change in the open circuit voltage in excess of a predetermined amount.
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32. An apparatus for charging a battery comprising the steps of:
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means for generating repetitive charging cycles having charging and multiple depolarization pulses and including at least two rest periods during which there is neither a charge nor a discharge current; means for measuring the open circuit voltage of the battery during at least an extended second or later rest period of charge cycles separated in time and at a time when the battery is in a state of equilibrium; means for comparing measured open circuit voltages; means for reducing the average charging current when the comparison step fails to yield a drop in the measured open circuit voltage; and means for terminating the charging cycles when the comparison step yields a negative change in the open circuit voltage.
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33. An apparatus for charging a battery comprising the steps of:
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means for generating repetitive charging cycles having charging and single depolarization pulses and including single rest periods during which there is neither a charge nor a discharge current; means for measuring the open circuit voltage of the battery during an extended rest periods of charge cycles separated in time and at a time when the battery is in a state of equilibrium; means for comparing measured open circuit voltages; means for reducing the average charging current when the comparison step fails to yield a drop in the measured open circuit voltage; and means for terminating the charging cycles when the comparison step yields a negative change in the open circuit voltage.
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Specification