Battery charger
First Claim
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1. A battery charger including:
- a voltage detection circuit for monitoring a voltage of a battery being charged and for providing sequentially a plurality of voltage values for the voltage of the battery being charged measured at a selected interval;
a comparator connected to compare each voltage value with a preceding voltage value within the sequence to determine a difference between each voltage value and the preceding voltage value;
a detector outputting an end of charge detection signal when said difference between a voltage value and a last preceding voltage value reflects a decrease of at least a threshold amount or when the voltage value does not exceed the last preceding voltage value.
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Abstract
An end-of-charge detection technique for a battery charger is described. The technique involves the detection of a voltage drop at the end of charging and eliminates the effect of noise spikes.
21 Citations
16 Claims
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1. A battery charger including:
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a voltage detection circuit for monitoring a voltage of a battery being charged and for providing sequentially a plurality of voltage values for the voltage of the battery being charged measured at a selected interval;
a comparator connected to compare each voltage value with a preceding voltage value within the sequence to determine a difference between each voltage value and the preceding voltage value;
a detector outputting an end of charge detection signal when said difference between a voltage value and a last preceding voltage value reflects a decrease of at least a threshold amount or when the voltage value does not exceed the last preceding voltage value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of detecting a voltage drop when charging a battery, the method comprising:
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monitoring a voltage of a battery being charged and providing sequentially a plurality of voltage values for the voltage of the battery being charged measured at a selected interval;
comparing each voltage value with a preceding voltage value to determine a difference a difference between each voltage value and the preceding voltage value within the sequence; and
producing an end of charge detection signal when said difference between a voltage value and a last preceding voltage value of at least a threshold amount or when the voltage value does not exceed the last preceding voltage value. - View Dependent Claims (10)
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11. A method of detecting a battery is fully charged, comprising:
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monitoring a voltage of the battery being charged at a selected interval;
storing the measured voltages in sequence;
comparing each voltage in the sequence with a preceding voltage; and
producing an end of charge detection signal when at least n measured voltages in the sequence each exhibit a decrease from a next previous measured voltage within the sequence, where n is at least two. - View Dependent Claims (12, 13, 14, 15, 16)
producing the end of charge detection signal when at least n measured voltages in the sequence each do not exceed a next previous measured voltage within the sequence.
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13. The method of claim 11, wherein the step of producing the end of charge detection signal further comprises:
producing the end of charge detection signal when each decrease between the n measured voltages and the next previous measured voltages exceeds a threshold amount.
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14. The method of claim 13, wherein the threshold amount is 50 mV.
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15. The method of claim 13, further comprising:
discarding a measured voltage which exhibits a decrease of at least the threshold amount from a next previous measured voltage within the sequence but which is not at least the threshold amount below a next subsequent measured voltage within the sequence.
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16. The method of claim 13, wherein the step of producing an end of charge detection signal results in switching from a fast charging mode to a trickle charging mode.
Specification