Zapping NiCads

In 1972, Popular Electronics had an article about how to fix NiCad batteries that had developed an internal short and would not take a charge. Last week I had two Dewalt battery packs (6 batteries in each) that wouldn't charge (charger gave the fast blink error). I hauled out my high-current power supply and zapped each cell 20 times. The packs both work fine now.
Note that you have to disassemble the battery pack to zap Ni-Cads because you must zap each individual cell, not the entire pack at once. Also this is not for NiMH cells or Li-Ion cells, only NiCad cells.
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I never had luck at maintaing operating voltage. If you don't run down the cells much, you might get by. They will try to go back to the shorted condition. I would say keep them on charge, but that is another reason they go ad. Good luck.
Greg
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IMO, once you dissassemble the battery pack, what's the point? The zapping may get you some more life, but it's not like it;s a new set of batteries. And considering the effort in taking apart and putting it back together, I'd just go with new. You can buy new batteries to replace them with on Ebay. I did that last year with my Dewalt driver/drill. For $17 it's better than when it was new 30 years ago.
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wrote:

or get the pack rebuilt by PRIMECELL.COM, higher capacity cells and fresh too:)
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wrote:

I suggest he find a local battery rebuilder and have them redone right with new cells. Or if your charger can handle them,get higher capacity NiMH cells installed.
they don't short like NiCds do.
--
Jim Yanik
jyanik
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Since the whisker grew in the first place, it'll grow right back.

Sometimes. For a short time. Bottom line; replace the cells.
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On May 31, 10:33am, " snipped-for-privacy@att.bizzzzzzzzzzzz"

If you can keep the battery pack on a constant ;low charge, that will usually prevent the wiskers from forming a real short, it apparantly burns them off oas the just get to the shorting point. But if no constant charging, then good luck.
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On Thu, 31 May 2012 10:33:36 -0700 (PDT), "hr(bob) snipped-for-privacy@att.net"

Requiring a constant charge makes a batteries pretty useless. ;-)
The point being, that once a dendrite forms, it's made a channel through the insulator. After (part of) that dendrite is burned out, another will quickly form because 1) the insulation barrier is compromised, and 2) because the dendrite isn't completely gone. It will regrow quickly.
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