Battery charger and method of charging batteries
First Claim
1. A method of charging a rechargeable battery comprising:
- measuring an initial temperature Ti of the battery;
charging the battery with a charging current;
sensing a charging temperature T of the battery;
comparing the charging temperature T of the battery to the initial temperature Ti of the battery to derive a temperature factor which indicates a need to adjust the charging current;
sampling an open circuit voltage VOCV of the battery;
compiling values for the open circuit voltage VOCV with respect to charging time t elapsed;
analyzing the compiled values for VOCV and t to identify one or more VOCV points which indicate a need to adjust the charging current;
continuing charging if the temperature factor or VOCV points are not identified; and
adjusting the charging current if the temperature factor or VOCV points are identified.
1 Assignment
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Accused Products
Abstract
A battery charger and method of charging a rechargeable battery which comprises charging the battery with an initial charging current and measuring and comparing the charging temperature to an initial temperature to identify a temperature factor which either identifies a need to lower the current or terminate the charging current. The temperature factor may be a temperature gradient ΔT. The open circuit voltage may be monitored from the beginning or may begin when ΔT is identified. VOCV is plotted with respect to time t elapsed to identify a point or points on the VOCV (t) curve, such as an inflection point in the dVOCV /dt data or a transition point in the d2 VOCV /dt2 which indicate the onset of overcharge. If the open circuit voltage VOCV of the battery is sampled from the beginning of charging the second order differential information should be ignored until a predetermined temperature gradient is realized. If a point indicating onset of overcharge is not recognized then charging is continued and the steps above are repeated until a point or points indicating onset of overcharge are identified. As a safeguard against overcharge, the inflection point on dVOCV /dt curve is utilized to indicate onset of overcharge even if the inflection point on the d2 VOCV /dt2 curve is not identified and the negative slope--dVOCV /dt is utilized to indicate onset of overcharge if the inflection point on the dVOCV /dt data is not identified.
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Citations
45 Claims
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1. A method of charging a rechargeable battery comprising:
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measuring an initial temperature Ti of the battery; charging the battery with a charging current; sensing a charging temperature T of the battery; comparing the charging temperature T of the battery to the initial temperature Ti of the battery to derive a temperature factor which indicates a need to adjust the charging current; sampling an open circuit voltage VOCV of the battery; compiling values for the open circuit voltage VOCV with respect to charging time t elapsed; analyzing the compiled values for VOCV and t to identify one or more VOCV points which indicate a need to adjust the charging current; continuing charging if the temperature factor or VOCV points are not identified; and adjusting the charging current if the temperature factor or VOCV points are identified. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A battery charger for charging a rechargeable battery comprising:
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a power supply to provide charging current to said battery or cell; a temperature sensor for sensing an initial temperature Ti and a charging temperature T of the battery; a temperature comparator for comparing the charging temperature T to the initial temperature Ti to derive a temperature factor which indicates the need to adjust the charging current; a charge interrupter for periodically interrupting the charging current; a voltage sensor for sampling an open circuit voltage VOCV of the battery; a data compiler for compiling and analyzing the values of VOCV with respect to charging time t elapsed to identify a VOCV point indicating a need to adjust the current; a charging current adjuster for adjusting the charging current when the temperature factor or VOCV points are identified. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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Specification