Battery recharging system with signal-to-noise responsive falling voltage slope charge termination
First Claim
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1. A method of charging a battery comprising the steps of:
- applying a charging current to the battery;
for a first time interval, testing the battery to obtain data of battery voltage as a function of time and evaluating said data to determine if the time rate of change of said voltage is not positive during said first time interval;
terminating the application of charging current to the battery if said time rate of change is not positive during said first time interval;
after the completion of said first time interval, waiting for a second time interval;
after the completion of said second time interval, testing the battery to obtain data of battery voltage as a function of time and evaluating said data to determine if the time rate of change of said voltage is not positive at any time after said second time interval;
terminating the application of charging current to the battery if said time rate of change is not positive at any time after said second time interval.
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Abstract
The falling voltage slope charge termination routine is performed during intervals of the charging cycle in which signal-to-noise ratio is comparatively high. The falling voltage slope charge termination technique is automatically disabled or rendered less sensitive to noise during times when the signal-to-noise ratio is comparatively low. In this way, accurate charge termination is accomplished without error otherwise induced by voltage noise during charging. The charge termination technique responds quickly to a charged battery indication, since signal averaging to negate the effects of noise can be minimized or eliminated.
22 Citations
23 Claims
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1. A method of charging a battery comprising the steps of:
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applying a charging current to the battery; for a first time interval, testing the battery to obtain data of battery voltage as a function of time and evaluating said data to determine if the time rate of change of said voltage is not positive during said first time interval; terminating the application of charging current to the battery if said time rate of change is not positive during said first time interval; after the completion of said first time interval, waiting for a second time interval; after the completion of said second time interval, testing the battery to obtain data of battery voltage as a function of time and evaluating said data to determine if the time rate of change of said voltage is not positive at any time after said second time interval; terminating the application of charging current to the battery if said time rate of change is not positive at any time after said second time interval. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of charging a battery comprising the steps of:
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applying a charging current to the battery; for a first time interval, obtaining samples of battery voltage at a first predetermined sampling rate to obtain data of battery voltage as a function of time; after completion of said first time interval, for a second time interval, obtaining samples of battery voltage at a second predetermined sampling rate longer than said first rate to obtain data of battery voltage as a function of time; after completion of said second time interval, obtaining samples of battery voltage at a third predetermined sampling rate shorter than said second sampling rate; evaluating said data to determine if the time rate of change of said voltage is not positive during said first time interval; and terminating the application of charging current to the battery if said time rate of change is not positive during said first time interval. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for charging a battery comprising steps of:
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supplying charge current to the battery; measuring the slope of the battery voltage verses time curve to determine when the supplying of charge current to the battery should be terminated; obtaining battery voltage data during the measuring step at a first sampling rate in a first time interval when the slope of the voltage curve exceeds a predetermined value; obtaining battery voltage data during the measuring step at a second sampling rate less than the first sampling rate in a second time interval when the slope of the voltage curve is less than the predetermined value; and terminating the supplying of charge current when the slope of the battery voltage curve is not positive. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification