Battery rebuild

Discussion in 'The Projects Forum' started by specklehunter, Nov 16, 2014.

  1. specklehunter

    Thread Starter New Member

    Nov 16, 2014
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    I'm not sure if this is the right place to post this but............I have a pile of power tool batteries that are bad and am trying to save a few bucks and rebuild them myself. I bought some 2.8 mah sub c nicad batteries to rebuild a pack that was originally rated at 2.4(which I assume is fine to do). I organized the batteries like the old ones and soldered them in place. When I put them on charge, they charged for about five minutes and the charger cut off saying fully charged. I attached it to my drill and it had very little power. It turned the drill but I could stop it by hand, which I shouldn't be able to do. I then tried a different charger and the same thing happened. So now I am puzzled. Are the batteries bad? Well.....it is an 18 volt pack so I used 15 1.2 volt batteries and they are checking at 21 volts. I'm not sure why its too high but I assume that's okay. Could the chargers be bad? Could the thermistor n the pack be bad? I'm at a loss as to what to do next..........Any advice would be greatly appreciated!
     
  2. specklehunter

    Thread Starter New Member

    Nov 16, 2014
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    This is a Milwaukee battery and charger by the way.
     
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    A "2.8 mah" NiCd battery is a very small battery. Are you sure? I have never seen a sub-C NiCd that small.

    Are you sure they are NiCd's? If the charger is designed for a different chemistry, e.g., Li-ion, it may not work well with NiCd's. How do you know they are NiCd's?

    Can you post a picture of your re-built batteries?

    John
     
  4. specklehunter

    Thread Starter New Member

    Nov 16, 2014
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    It should have been 2.8 ah. sorry. They are definitely nicads and I am using the stock multi chemistry charger that came with the product.
     
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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  6. tcmtech

    Well-Known Member

    Nov 4, 2013
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    I've ran into that problem a few times when rebuilding stock Craftsman battery packs with a higher capacity and quality type of cell.

    The thing I do once the battery pack is assembled and working is to put a moderately sized low resistance load on it and let it suck the battery flat dead overnight then put it on the charger for a full 24 hours. A lot of times they will go green within a few minutes then switch back to red charge mode over the next few hours and charge up all the way.
     
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