How can I get my batteries to charge?

May 30, 2007 1:58 PM

Fixing problems with a 14.4 V cordless tool charger, or if that doesn't work, turning it into a "corded tool."

I received a set of 14.4V durabuilt (target brand) power tools for my birthday roughly 2 years ago. The problem is both of the included battery packs are dead, and the charger won't even try to charge them.

(On the charger there's an on light, an off light and a set button, no matter how worn down the battery, the on light won't go on).

Is there something I can do to fix this (even if just tweaking the electronics)?

If not, would there be any reason why I shouldn't build a 14.4V XAmp power supply into one of the battery packs and make it so I can at least use the tools with a cord?

posted by drezdn to technology (3 comments total)

Batteries are dangerous. Don't touch them they'll blow up and kill everyone you ever met. But...

There is no real way of knowing what sort of electronics are in the battery and/or charger that are causing the problem (the "won't try to charge" problem that is). You could crack open the battery packs and replace the cells inside (it will just be a bunch if NiCd cells soldered together).

Or to try to force charge the cells, a simple NiCd charger is to set up a constant current at about 0.1C to the pack for 15 hours. Again you'd have to crack it open and hook directly to the string of cells inside in case some of the control electronics are inside the battery pack (which is common).

"C" is the amp-hour rating of the cells, so if they are 1700mAh you would hook up a 170mA current for 15 hours. A DC supply bigger than 14.4V and a resistor in series calculated to set the current to 170mA will approximate this closely enough.

As for building a suitable direct supply, the problem you'll run in to is that things like drills draw a pretty big current, and you might find that building a big enough supply will cost more than buying some new tools. A friend runs his drill off a car battery and a lead. For DC motors voltage = speed, so your tools will run slow if you try this, but it'll be easier than building a 3 or 4 amp supply and avoids running mains power into a case not designed for it.
posted by markr at 3:29 PM on May 30, 2007

Are the contact points on the charger possibly covered with battery juice/crud? If it's possible, try cleaning with a brush or perhaps distilled water...
posted by acro at 4:45 PM on May 30, 2007

Lol, this is an easy one.

See the screws on the battery packs? On top of 'em?

Unscrew those. Pop off the top piece, it's the MALE piece and usually part of the base.

Look inside, what do you see? Aha! Those are AA batteries! (or D cells, or C cells, depending.)

Pop 'em out and replace 'em with NiMH batteries equaling the same voltage (or more, or less, seriously it's not going to be a big deal.) The mAh really don't matter either, whether they're 2100's or 2500's or 2700's.

Anyway, you'll have better performing longer lasting batteries. Lots and *lots* of people do this with their tougher drills (DeWalt's, hitachi's, Milwaukee's etc.) when their batteries die, it's a LOT cheaper than replacing the craptastic NiCad's and...you get a better performing product.

On, and FWIW, the Hitachi green-stupid-looking cordless drivers are, imo, amazing. Should you come to the junction to buy more, I'd suggest the 14.4v one---you'll be AMAZED at the difference between a real driver and your durabrand. :)
posted by TomMelee at 5:57 PM on May 30, 2007 [1 favorite]