Battery charging
First Claim
1. A method of charging a battery, comprising the steps of:
- (a) supplying a plurality of current pulses of a first type to the battery;
(b) measuring the off-load voltage of the battery between current pulses of said first type;
(c) determining a first voltage drop during a first period following a current pulse of said first type;
(d) determining a second voltage drop during a second period following said current pulse of said first type of said step (c) but before a next current pulse of said first type, where the end of said second period is later than the beginning of said first period;
(e) determining the ratio of said first and second voltage drops;
(f) repeating said steps (c) to (e) for subsequent current pulses of said first type to form a sequence of ratios; and
(g) stopping the supply of said current pulses of said first type after said sequence of ratios has reached a peak value and when a ratio is determined which is less than said peak value by a predetermined amount or proportion.
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Abstract
A battery charger comprises a power supply for supplying current pulses to a battery to be charged. A microprocessor receives from an analog-to-digital converter codes representing the voltage between the battery terminals with the battery off-load between charging pulses and monitors the ratio of the voltage difference (V3 -V5) during a first period following a charging pulse to the voltage difference (V10 -V12) over a second period following the charging pulse, with the second period ending after the beginning of the first period. The value of this ratio reaches a peak value and then declines, and the microprocessor determines when the value of the ratio falls below a peak value thereof by a predetermined amount to terminate fast charging of the battery, after which the battery may be removed or may remain on a trickle charge. An accurate, reliable, and consistent determination of completion of charging of sealed nickel-cadmium batteries is thus provided.
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Citations
20 Claims
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1. A method of charging a battery, comprising the steps of:
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(a) supplying a plurality of current pulses of a first type to the battery; (b) measuring the off-load voltage of the battery between current pulses of said first type; (c) determining a first voltage drop during a first period following a current pulse of said first type; (d) determining a second voltage drop during a second period following said current pulse of said first type of said step (c) but before a next current pulse of said first type, where the end of said second period is later than the beginning of said first period; (e) determining the ratio of said first and second voltage drops; (f) repeating said steps (c) to (e) for subsequent current pulses of said first type to form a sequence of ratios; and (g) stopping the supply of said current pulses of said first type after said sequence of ratios has reached a peak value and when a ratio is determined which is less than said peak value by a predetermined amount or proportion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 9, 10, 11, 12)
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8. A method as set forth in claim 8, wherein the average current in amps of said current pulses of said second type is equal to one tenth of the capacity of the battery in amp-hours.
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13. An apparatus for charging a battery, comprising:
- means for supplying current pulses of a first type to the battery;
means for measuring the off-load voltage of the battery between said current pulses; and
means for determining the first voltage drop during a first time period following each of at least some of said current pulses, for determining the second voltage drop during a second period following each of said at least some of said current pulses wherein the end of each said second period follows the beginning of each said first period, for determining the ratios of said first and second voltage drops, and for preventing said pulse supplying means from supplying said current pulses of said first type when the value of said ratio falls below a peak value of said ratios by a predetermined amount. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
- means for supplying current pulses of a first type to the battery;
Specification