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Dewalt Battery Charger Output Voltage

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Chris F.

Jan 1, 1970
0
Someone brought me a Dewalt cordless 14.4V drill that was totally dead.
I've determined that the drill works and the battery is faulty, but am
uncertain about the charger. The output of the charger measures about 47
volts - that seems way too high, but I thought perhaps it was designed this
way to provide a rapid charge. Is that the case, or has the charger (a
switching power supply type) gone out of regulation and ruined the battery?
Thanks for any help.
 
D

Dave Plowman (News)

Jan 1, 1970
0
Someone brought me a Dewalt cordless 14.4V drill that was totally
dead. I've determined that the drill works and the battery is faulty,
but am uncertain about the charger. The output of the charger measures
about 47 volts - that seems way too high, but I thought perhaps it was
designed this way to provide a rapid charge. Is that the case, or has
the charger (a switching power supply type) gone out of regulation and
ruined the battery?
Thanks for any help.

Open circuit voltages are rarely a guide to anything. The internal
resistance of Ni-Cads, etc, is extremely low, and a genuine 47 volts
across a 14.4 pack would blow it into the middle of next week.
 
G

GregS

Jan 1, 1970
0
Open circuit voltages are rarely a guide to anything. The internal
resistance of Ni-Cads, etc, is extremely low, and a genuine 47 volts
across a 14.4 pack would blow it into the middle of next week.

It should be easy to connect some resistors and measure the chargers
capabilities.

greg
 
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James Thompson

Jan 1, 1970
0
Chris F. said:
Someone brought me a Dewalt cordless 14.4V drill that was totally dead.
I've determined that the drill works and the battery is faulty, but am
uncertain about the charger. The output of the charger measures about 47
volts - that seems way too high, but I thought perhaps it was designed
this way to provide a rapid charge. Is that the case, or has the charger
(a switching power supply type) gone out of regulation and ruined the
battery?
Thanks for any help.
I believe that type of charger is more current pulse width controlled then
voltage. get a 10 ohm 10 watt resistor as a load with a current meter is
series and see what it puts out current wise. If you have another meter
handy measure the voltage across the resistor and that should tell is the
charger is working ok.
I also have 2 of those dewalt chargers and they do put out a higher voltage
then you would expect, as like you stated for rapid charge batteries.
 
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