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Thread: Zapping Nicads works

  1. #1

    Default Zapping Nicads works

    I have a 9.6v Black and Decker drill and one day I picked it up and it did nothing and so I charged it and it worked some then quit. I decided the batteries had gone bad so I took it apart and tested them and had 2 that measured 0.0v. I put it on the charger for about 5 minutes and measured them again... 2 of them 0.0v the rest about 1.3v or so. I went ahead and cut them out of the packs and was looking for replacement 4/5 subC nicads even calling locally when I stubled across a page discussing zapping dead nicads with about 5-10A to nuke dendrites that form on cells which short them out. I tested the 0v ones to be short.... yes they were shorted. I thought... how can I zap these things? There sat on a shelf a 12/6 v battery charger for lead acid cells with a 0-1.2A scale and a 6A setting when clicked "on" I went ahead and put it on 6v and 6A and after zapping each cell I tested it... one measured 1.38v so I tried the next... nope... nope... zap... 1.3v or so.. I went ahead and resoldered the pack back together and measured it... 9.5v.... put it on the charger for awhile.... and then took it off and calculated it should be about 10v or so... still low checked all the batteries and another one was shorted..... ZAP 3 times... 1.3v. After charging for about 2 hours it measures about 11v now and the drill is spinning fast. I am unsure how much capacity the batteries have or if it will be fine tomorrow but zapping nicads seems to work if they are truly shorted. I may have saved myself about $10-$12 in batteries.
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  2. #2
    Flashaholic
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    Default Re: Zapping Nicads works

    Yes it works but it is temporary. Put your batteries aside and check them after two weeks - many of them will be shorted again (probably)

  3. #3

    Default Re: Zapping Nicads works

    Quote Originally Posted by czAtlantis View Post
    Yes it works but it is temporary. Put your batteries aside and check them after two weeks - many of them will be shorted again (probably)
    Just have to see what happens, maybe I will be lucky otherwise either I have to come across another pack of 4/5 subCs or order 8 of them and rebuild this one. If I knew of a cheap drill pack with the same type of batteries I could do that instead.
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  4. #4
    Flashaholic* 45/70's Avatar
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    Default Re: Zapping Nicads works

    Hi Lynx. I used to do this often, back when all we had, as far as cylindrical rechargeable cells, were NiCds. As cz said, it's really only a temporary fix.

    The problem is, when you zap the dendrites into nonexistence, you almost always also burn a hole through the separator. This of course "enhances" self discharge LOL!

    So, if you really need to get a NiCd cell, or pack going again, often zapping does work. The problem is, the cell now has a different problem, one that cannot be corrected.

    Dave
    Last edited by 45/70; 07-23-2012 at 08:00 PM. Reason: punct

  5. #5

    Default Re: Zapping Nicads works

    Quote Originally Posted by 45/70 View Post
    Hi Lynx. I used to do this often, back when all we had, as far as cylindrical rechargeable cells, were NiCds. As cz said, it's really only a temporary fix.

    The problem is, when you zap the dendrites into nonexistence, you almost always also burn a hole through the separator. This of course "enhances" self discharge LOL!

    So, if you really need to get a NiCd cell, or pack going again often, zapping does work. The problem is, the cell now has a different problem, one that cannot be corrected.

    Dave
    I didn't figure it would be a permanent fix for sure but at least it seems to work. I will check it in a week and see how much it has discharged.
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  6. #6
    Flashaholic* 45/70's Avatar
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    Default Re: Zapping Nicads works

    Yeah, do that. It doesn't always happen, it's possible to be lucky. It's just that you're zapping more than one cell more than once, and in my experience, this reduces the odds quite a bit.

    Dave

  7. #7

    Default Re: Zapping Nicads works

    Who knows, I could get lucky. I didn't know exactly what I was doing but I could have used 12v instead of 6v I just thought 6 would get the job done safer.
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  8. #8
    Flashaholic* Wrend's Avatar
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    Default Re: Zapping Nicads works

    I'm not exactly sure what you mean by get lucky. Basically, you're just keeping them on life support now. But hey, as long as they work well enough for you, that's what counts, I guess.

    If you do eventually decide to replace them with more NiCd cells, a couple tips to keep them lasting a long time are to not overcharge (except for perhaps once in a while to help balance them) nor trickle/maintenance charge them and to more fully discharge them before recharging them. When in series, don't discharge them too deeply because of the risk of reverse charging. Individually, it's likely best to completely discharge them and then store them shorted.

    I have some old NiCd packs that still work like new. One of them is over 15 years old now and still has more than its rated capacity for its intended use in an RC transmitter. Of course, that's only 500mAh, and I use Eneloops now instead in transmitters that can take them.

  9. #9

    Default Re: Zapping Nicads works

    It's been over a day now and the drill seems to be working normally I just tried it for a few seconds and unlike when I charged it for a day and pulled the trigger and it did nothing at all not even a groan.
    It has been about 2 weeks and I checked the battery pack... 3.6v and barely turned the drill over. I put it on the charger for about 6 hours and 11v and works fine so the pack seems to have developed high self discharge. I can still use it but I am guessing I would have to charge it weekly or before I use it.
    Luckily I realized that I inherited a dewalt 9.6v drill that uses the same battery packs and it has 2 batteries and I haven't even been using it so I can just use one of its batteries and keep the fast discharging pack for when I know I will need to use it a lot in a day charge it up ahead of time.
    Last edited by Lynx_Arc; 08-06-2012 at 09:21 PM.
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