Cordless device with battery imbalance indicator
First Claim
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1. A battery powered device for supplying power to a load comprising:
- a power supply connectable to the load and comprising first and second batteries;
the first and second batteries being connected in series with the voltage of each battery being summed with the voltage of the other battery to provide a summed voltage for application to the load;
a first voltage divider circuit across which is established a first voltage representative of the summed voltage and across a portion of which is established a second voltage representative of the voltage of the first battery;
a second voltage divider circuit across which is established a third voltage representative of the summed voltage and across a portion of which is established a fourth voltage representative of the voltage of the second battery;
a battery-connection circuit connected between the first and second batteries for establishing voltage levels representative of the actual voltage of the first and second batteries; and
a voltage detection circuit, connected to the first voltage divider circuit, the second voltage divider circuit and the battery-connection circuit, for detecting that the first battery is charged and the second battery is substantially discharged when the voltage of the second battery exceeds the voltage of the first battery by a first predetermined amount proportional to the summed voltage, and for detecting that the second battery is charged and the first battery is substantially discharged when the voltage of the first battery exceeds the voltage of the second battery by a second predetermined amount proportional to the summed voltage.
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Abstract
A cordless device 11 comprises a load 13 and a multiple pack power supply 15 connected to load 13. A voltage detection circuit 23, 63, 64, 75, 76 is connected to supply 15 and detects when one of the batteries 17, 19 is charged and the other is discharged. Circuits 23, 63, 65, 75, 76 may also function as a voltage comparator circuit to identify when one of the batteries 17, 19 is defective. The detection or comparator circuit includes comparators 25, 33 for comparing the battery voltages. An indicator 41, 43, 65, 74, 81 is connected to the output of comparators 25, 33 and provides an end user identifiable signal responsive to the outputs of comparators 25, 33.
44 Citations
24 Claims
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1. A battery powered device for supplying power to a load comprising:
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a power supply connectable to the load and comprising first and second batteries; the first and second batteries being connected in series with the voltage of each battery being summed with the voltage of the other battery to provide a summed voltage for application to the load; a first voltage divider circuit across which is established a first voltage representative of the summed voltage and across a portion of which is established a second voltage representative of the voltage of the first battery; a second voltage divider circuit across which is established a third voltage representative of the summed voltage and across a portion of which is established a fourth voltage representative of the voltage of the second battery; a battery-connection circuit connected between the first and second batteries for establishing voltage levels representative of the actual voltage of the first and second batteries; and a voltage detection circuit, connected to the first voltage divider circuit, the second voltage divider circuit and the battery-connection circuit, for detecting that the first battery is charged and the second battery is substantially discharged when the voltage of the second battery exceeds the voltage of the first battery by a first predetermined amount proportional to the summed voltage, and for detecting that the second battery is charged and the first battery is substantially discharged when the voltage of the first battery exceeds the voltage of the second battery by a second predetermined amount proportional to the summed voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A battery powered device for supplying power to a load comprising:
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a power supply connectable to the load and comprising first and second batteries which are connected in series; a first voltage divider circuit connected across the series-connected first and second batteries; a second voltage divider circuit connected across the series-connected first and second batteries; and a voltage comparator circuit connected to the first and second voltage divider circuits and to a juncture between the first and second batteries for generating a signal (a) when the first battery is charged and the second battery is substantially discharged and (b) when the second battery is charged and the first battery is substantially discharged. - View Dependent Claims (15)
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16. A battery powered device for supplying power to a load comprising:
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a power supply connectable to the load and comprising first and second batteries which are connected in series; a first voltage divider circuit connected across the series-connected first and second batteries; a second voltage divider circuit connected across the series-connected first and second batteries; and a voltage comparator circuit, connected to the first and second voltage divider circuits and to a juncture between the first and second batteries, for comparing the sum of the voltages of the first and second batteries to the voltage of the second battery and generating an output signal when the difference between the voltage sum and the second battery exceeds a predetermined absolute value proportionate to the voltage sum. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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Specification