Method and apparatus for charging batteries
First Claim
1. An apparatus for charging a rechargeable battery, said apparatus comprising:
- generator means for generating a charging current having a variable level, and during a first charging period said current having a level to rapidly charge the battery at a rate in amperes greater than the capacity in ampere-hours of the battery;
controller means for controlling said generator means, said controller means including,(a) means for varying said charging current for a predetermined variation interval and during said variation interval said charging current being maintained at a non-zero, non-negative value;
(b) means for determining a resistance free voltage value for the battery during said variation interval;
(c) means for comparing a reference voltage to said resistance free voltage value for the battery;
(d) means for controlling the level of said charging current in response to said resistances free voltage.
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Accused Products
Abstract
A charger for charging a rechargeable battery. The charger comprising a circuit for producing a charging current having a variable level and a control circuit for controlling the charging current. During a first charging period the current is maintained at a level to rapidly charge the battery at a rate in amperes which is greater than the capacity of the battery in ampere-hours. The controller includes means for interrupting the charging current for a predetermined interruption interval. During the interruption interval, the charging current is maintained at a non-zero value. The controller also includes means for determining a resistance free voltage for the battery. During a subsequent charging period, the charging current is controlled in response to the value of the resistance free voltage.
69 Citations
33 Claims
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1. An apparatus for charging a rechargeable battery, said apparatus comprising:
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generator means for generating a charging current having a variable level, and during a first charging period said current having a level to rapidly charge the battery at a rate in amperes greater than the capacity in ampere-hours of the battery; controller means for controlling said generator means, said controller means including, (a) means for varying said charging current for a predetermined variation interval and during said variation interval said charging current being maintained at a non-zero, non-negative value; (b) means for determining a resistance free voltage value for the battery during said variation interval; (c) means for comparing a reference voltage to said resistance free voltage value for the battery; (d) means for controlling the level of said charging current in response to said resistances free voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for charging a rechargeable battery comprising the steps of:
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(a) generating a charging current having a variable level; (b) maintaining said charging current during a first charging period at a level to rapidly charge the battery at a rate in amperes greater than the capacity in ampere-hours of the battery; (c) changing said charging current for a predetermined variation interval; (d) maintaining said charging current at a non-zero, non-negative value during said variation interval; (e) determining a resistance free voltage value for the battery after said change; and (f) varying the level of said charging current in response to said resistance free voltage value determined in step (e). - View Dependent Claims (20, 21, 22, 23, 24, 25, 27, 28)
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28. The method as claimed in claim 27, wherein said step for determining a resistance free voltage value for the battery comprises calculating a value for the resistance free voltage according to the expression:
space="preserve" listing-type="equation">V.sub.RF =V.sub.Hi -R I.sub.Hi.
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26. The method as claimed in claimed 19, wherein said step for determining a resistance free voltage value for the battery comprises inputting high and low voltage readings and high and low current readings for the battery during said variation interval, and calculating a resistance free voltage value from said input voltage and current readings according to the expression:
- ##EQU4##
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29. A method for determining a resistance free voltage value during the charging cycle when a charging current is applied to a rechargeable battery, said method comprising the steps of:
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(a) varying said charging current for a predetermined interval; (b) inputting high and low voltage readings and high and low current readings for the battery during said predetermined interval; and (c) calculating a resistance free voltage value from said input voltage and current readings according to the expression;
##EQU5## - View Dependent Claims (30, 31, 32, 33)
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Specification