Battery pack and cordless power tool using the same as power source
First Claim
1. A battery pack having a positive terminal and a negative terminal, comprising:
- a battery including a plurality of chargeable battery cells connected in series, the battery having a first terminal connected to the positive terminal and a second terminal connected to the negative terminal;
a battery voltage detector for detecting a battery voltage across the first terminal and the second terminal of the battery;
detection means for detecting, based on the battery voltage detected by the battery voltage detector, that the battery has reached a charge-need condition indicating that the battery needs to be charged, the detection means outputting a detection signal when the charge-need condition is detected; and
alerting means, responsive to the detection signal, for alerting a user to charge the battery during use of the battery as a power source for a load connected between the positive terminal and the negative terminal, the alerting means giving a physically perceivable impression to the user so that the user can recognize the charge-need condition of the battery.
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Accused Products
Abstract
To prevent a battery from being over-discharged and to thus improve a cycle life of the battery, a microcomputer electrically interrupts connection between the battery and a cordless power tool to compulsorily stop driving the tool when the battery voltage has become equal to or fallen below a first predetermined value. Also, to enable an operator to know that the battery is in a near over-discharge condition, the microcomputer performs a switching control of a load current when the battery voltage is above the first predetermined voltage but has become equal to or falls below the second predetermined voltage. As a result, the rotation of the motor of the tool goes abruptly slow down or the motor rotates in an irregular fashion, whereby the operator recognizes that the battery is in a charge-need condition.
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Citations
20 Claims
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1. A battery pack having a positive terminal and a negative terminal, comprising:
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a battery including a plurality of chargeable battery cells connected in series, the battery having a first terminal connected to the positive terminal and a second terminal connected to the negative terminal;
a battery voltage detector for detecting a battery voltage across the first terminal and the second terminal of the battery;
detection means for detecting, based on the battery voltage detected by the battery voltage detector, that the battery has reached a charge-need condition indicating that the battery needs to be charged, the detection means outputting a detection signal when the charge-need condition is detected; and
alerting means, responsive to the detection signal, for alerting a user to charge the battery during use of the battery as a power source for a load connected between the positive terminal and the negative terminal, the alerting means giving a physically perceivable impression to the user so that the user can recognize the charge-need condition of the battery. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 17, 18, 19, 20)
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11. An electrically powered tool comprising:
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a motor having a first positive terminal and a first negative terminal;
a battery including a plurality of chargeable battery cells connected in series, the battery having a second positive terminal connected to the first positive terminal and a second negative terminal connected to the first negative terminal, the battery serving as a power source for the motor;
a battery voltage detector for detecting a battery voltage across the second positive terminal and the second negative terminal;
detection means for detecting, based on the battery voltage detected by the battery voltage detector, that the battery has reached a charge-need condition indicating that the battery needs to be charged, the detection means outputting a detection signal when the charge-need condition is detected; and
alerting means, responsive to the detection signal, for alerting a user to charge the battery, the alerting means giving a physically perceivable impression to the user so that the user can recognize the charge-need condition of the battery. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification