Battery charger
First Claim
1. A battery charger for charging a rechargeable battery having a plurality of cells, comprising:
- charge current supplying means for supplying a charge current to the battery;
voltage detecting means for detecting a voltage across the battery and for outputting a battery voltage signal indicative of the voltage across the battery;
battery status detecting means for detecting a status of the battery as to whether the battery is at low charge or at high charge, said battery status detecting means detecting the status of the battery based on a reference voltage and a first battery voltage signal indicative of the voltage across the battery at a time after expiration of a predetermined period of time from start of charge; and
control means for controlling the charge of the battery base on the status of the battery detected by said battery status detecting means, said control means having full charge detection means for detecting that the battery has reached a full charge condition based on the voltage indicated by the battery voltage signal, wherein said control means stops charging when the full charge condition is detected by said full charge detection means;
wherein the reference voltage is a voltage across the battery detected by said voltage detecting means at the start of charge, and wherein said battery status detecting means computes a change in the voltage across the battery over the predetermined period of time and determines that the battery is at low charge when the change in the voltage across the battery is equal to or smaller than a predetermined value and that the battery is at high charge when the change in the voltage across the battery is larger than the predetermined value.
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Accused Products
Abstract
A status of a battery is detected to determine whether an amount of residual charge is large or not. Detection of the status of the battery is performed on the basis of a change in the voltage level over a preliminary charge time. If the battery is determined to at low charge, then a sleep time is set. The full charge condition of the battery is, for example, detected when a second order differential of the voltage across the battery becomes negative. However, the computation of the second order differential is not performed during the sleep time. Further, to accurately determine the status of the battery, the duration of the preliminary charge time is prolonged if the battery is detected to have been deeply discharged.
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Citations
24 Claims
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1. A battery charger for charging a rechargeable battery having a plurality of cells, comprising:
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charge current supplying means for supplying a charge current to the battery; voltage detecting means for detecting a voltage across the battery and for outputting a battery voltage signal indicative of the voltage across the battery; battery status detecting means for detecting a status of the battery as to whether the battery is at low charge or at high charge, said battery status detecting means detecting the status of the battery based on a reference voltage and a first battery voltage signal indicative of the voltage across the battery at a time after expiration of a predetermined period of time from start of charge; and control means for controlling the charge of the battery base on the status of the battery detected by said battery status detecting means, said control means having full charge detection means for detecting that the battery has reached a full charge condition based on the voltage indicated by the battery voltage signal, wherein said control means stops charging when the full charge condition is detected by said full charge detection means; wherein the reference voltage is a voltage across the battery detected by said voltage detecting means at the start of charge, and wherein said battery status detecting means computes a change in the voltage across the battery over the predetermined period of time and determines that the battery is at low charge when the change in the voltage across the battery is equal to or smaller than a predetermined value and that the battery is at high charge when the change in the voltage across the battery is larger than the predetermined value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A battery charger for charging a rechargeable battery having a plurality of cells, comprising:
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charge current supplying means for supplying a charge current to the battery; voltage detecting means for detecting a voltage across the battery and outputting a battery voltage signal indicative of the voltage across the battery; first battery status detecting means for detecting a status of the battery as to whether or not the battery has been deeply discharged, said battery status detecting means detecting the status of the battery based on a reference voltage and a first battery voltage signal indicative of the voltage across the battery at a time before the charge current is supplied to the battery by said charge current supplying means; second battery status detecting means for detecting a status of the battery as to whether the battery is at low charge or at high charge, said battery status detecting means detecting the status of the battery based on a reference voltage and a second battery voltage signal indicative of the voltage across the battery at a time after expiration of a preliminary charge time from a start of charge; time adjusting means for adjusting a duration of the preliminary charge time in accordance with the status of the battery detected by said first status detecting means; and control means for controlling the charge of the battery based on the status of the battery detected by said second battery status detecting means, said control means having full charge detection means for detecting that the battery has reached a full charge condition based on the voltage indicated by the battery voltage signal, wherein said control means stops charging when the full charge condition is detected by said full charge detection means. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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Specification