Battery management system and method
First Claim
1. A method for managing a battery having a string of units electrically connected in series, each of the units having positive and negative terminals, the method comprising the steps of:
- supplying charge selectively to a selected single unit of the string of units electrically connected in series with a charging circuit;
measuring the voltage across the terminals of the selected unit of the battery with a single voltage detector circuit;
recording an output of the voltage detector; and
detecting a discharge knee characteristic of the battery based on the output from the voltage detector for the unit, detecting the discharge knee including the steps of;
periodically sampling a voltage of the selected unit;
comparing a sum of sampled voltages for a first selected time interval to a sum of sampled voltages for a second selected time interval; and
determining a knee discharge characteristic if a difference between the compared sums exceeds a threshold value.
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Abstract
A battery management system is disclosed for control of individual cells in a battery string. The battery management system includes a charger, a voltmeter, a selection circuit and a microprocessor. Under control of the microprocessor, the selection circuit connects each cell of the battery string to the charger and voltmeter. Information relating to battery performance is recorded and analyzed. The analysis depends upon the conditions under which the battery is operating. By monitoring the battery performance under different conditions, problems with individual cells can be determined and corrected.
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Citations
13 Claims
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1. A method for managing a battery having a string of units electrically connected in series, each of the units having positive and negative terminals, the method comprising the steps of:
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supplying charge selectively to a selected single unit of the string of units electrically connected in series with a charging circuit; measuring the voltage across the terminals of the selected unit of the battery with a single voltage detector circuit; recording an output of the voltage detector; and detecting a discharge knee characteristic of the battery based on the output from the voltage detector for the unit, detecting the discharge knee including the steps of; periodically sampling a voltage of the selected unit; comparing a sum of sampled voltages for a first selected time interval to a sum of sampled voltages for a second selected time interval; and determining a knee discharge characteristic if a difference between the compared sums exceeds a threshold value. - View Dependent Claims (2, 3, 4, 6, 7, 8, 9)
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5. A method for managing a battery having a string of units electrically connected in series, each of the units having positive and negative terminals, the method comprising the steps of:
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supplying charge to a selected unit of the battery with a charging circuit; measuring the voltage across the terminals of the selected unit of the battery with a single voltage detector circuit; recording an output of the voltage detector; detecting a discharge knee characteristic of the battery based on the output from the voltage detector for the unit, detecting the discharge knee including the steps of; periodically sampling a voltage of each unit in the battery; summing together the sampled voltages over selected time intervals; comparing a sum of sampled voltages for a first selected time interval to a sum of sampled voltages for a second selected time interval; and determining a knee discharge characteristic if the difference between the compared sums exceeds a threshold value.
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10. A method for detecting a discharge knee of a battery using an apparatus including storage and a processor coupled to the storage, the method comprising the steps of:
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periodically sampling, by the processor, a voltage in the battery; comparing, by the processor, a sum of sampled voltages for a first selected time interval to a sum of sampled voltages for a second selected time interval; and determining, by the processor, a knee discharge characteristic if a difference between the compared sums exceeds a threshold value. - View Dependent Claims (11, 12, 13)
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Specification