Battery recharging system with state of charge detection that initially detects whether a battery to be charged is already at or near full charge to prevent overcharging
First Claim
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1. A method of charging a battery comprising:
- detecting the state of charge prior to charging;
initiating charging while monitoring the battery voltage variation with time;
terminating charging in accordance with the following;
(a) if the detected state of charge prior to charging is above a predetermined level, terminating charging in response to a fall in the value of the first derivative of the voltage variation with time; and
(b) if the detected state of charge prior to charging is below a predetermined level, terminating charging in response to a change from a rising to a falling value of the first derivative of the voltage variation with time.
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Abstract
A state of charge test is first performed on the battery by applying a current pulse and then observing the voltage decay characteristics which result. Batteries which are initially nearly fully charged exhibit a larger voltage decay than batteries which are not as fully charged. The result of this initial state of charge test is used to determine how to best terminate battery charging. In this way battery overcharging is prevented regardless of the initial state of charge of the battery.
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Citations
47 Claims
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1. A method of charging a battery comprising:
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detecting the state of charge prior to charging; initiating charging while monitoring the battery voltage variation with time; terminating charging in accordance with the following; (a) if the detected state of charge prior to charging is above a predetermined level, terminating charging in response to a fall in the value of the first derivative of the voltage variation with time; and (b) if the detected state of charge prior to charging is below a predetermined level, terminating charging in response to a change from a rising to a falling value of the first derivative of the voltage variation with time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of charging a battery comprising:
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detecting the state of charge prior to charging by applying a current to said battery, then removing the applied current and measuring the battery voltage decay after removing the current and using the decay as an indication of the state of charge of the battery; controlling charging in accordance with the following; (a) if the detected state of charge prior to charging is above a predetermined level, terminating charging; and (b) if the detected state of charge prior to charging is below a predetermined level, initiating charging while monitoring the battery voltage variation with time, and terminating charging in response to a change from a rising to a falling value of the first derivative of the voltage variation with time. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. The method of determining the state of charge of a battery comprising:
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applying a current to said battery; thereafter removing the applied current; and measuring the battery voltage decay after removing the current and using the voltage decay as an indication of the state of charge of the battery. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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34. The method of controlling the charging operation of a battery charger comprising:
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applying a current to said battery; thereafter removing the applied current; and measuring the battery voltage decay after removing the current and using the voltage decay as an indication of the state of charge of the battery; and if the detected state of charge is above a predetermined level, terminating the charging operation; if the detected state of charge is below a predetermined level, permitting the charging operation to proceed. - View Dependent Claims (35, 36, 37, 38, 39, 40)
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41. A method of charging a battery comprising the steps of:
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detecting the state of charge of the battery prior to charging by applying a current to said battery for a relatively brief period of time, removing the applied current, and then measuring the battery voltage decay as an indication of the state of charge of the battery; and controlling charging of the battery in accordance with the initially detected state of charge of the battery. - View Dependent Claims (42, 43, 44, 45, 46, 47)
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Specification