Charging batteries from sources other than the recommended charger

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Forum topic by David posted 06-02-2011 05:05 PM 1248 views 0 times favorited 2 replies Add to Favorites Watch
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199 posts in 2903 days

06-02-2011 05:05 PM

Topic tags/keywords: battery charging tools nicad nicd lithium

In response to , I was blocked so I figured I’d just start a new forum topic…

NiCd battery chargers like the ones Dewalt uses charge with a constant current, and detect end of charge by watching the cell voltage and stopping the charge when it droops slightly (-dV). This is why they can charge a range of pack voltages with one charger and do it fairly quickly. Connecting directly to a car battery will not offer this protection. The reason I haven’t done this is because I know it can damage the battery.

I don’t know exactly how they charge lithium packs with the same charger, but I’m guessing the charger can detect if it’s a lithium pack and adjusts the charge profile accordingly. Anyone know what chemistry Dewalt uses in their lithium packs?

The drill will run just fine, motors are pretty tolerant of differing voltages.

-- Perilous to all of us are the devices of an art deeper than we ourselves possess. --Gandalf the Grey

2 replies so far

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4032 posts in 3211 days

#1 posted 06-02-2011 05:38 PM

I haven’t done it, but plan to take the works out of a dead ni-cad battery pack for one of my older 12volt drills and solder a power cord into the empty battery shell with an automotive lighter type plug on the other end. I don’t stand to loose anything here since it’s an old drill for which it has become difficult to find a replacement battery. My battery has only two contact blades to connect to the drill so this is easy to figure out. I think some of the newer batteries, with more features, have more connections and might be less simple to bypass.; but I’m not positive about that.

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3261 posts in 2915 days

#2 posted 06-03-2011 05:30 AM

I had an old old 7.2V Bosch drill that had no charger so I used alligator clips and my car battery charger with no ill affects. I also felt I had nothing to lose. I used it a long time and finally got a 12V Dewalt and gave the old Bosch to a friend that had another drill and a working charger.

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