Dewalt Battery Charger Output Voltage

Aug 01, 2006 3 Replies
C

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.


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D

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.

*Some people are alive only because it's illegal to kill them * Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound.
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G

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

greg

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J

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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