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Soldering onto NiMH batteries?

Discussion in 'Electronic Basics' started by DeanB, Jun 19, 2008.

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  1. DeanB

    DeanB Guest

    Hello all,

    I've only done a little soldering before, but I want to rebuild a
    battery pack for my TI-59 calculator (which is basically 3 AA-sized
    batteries soldered together in series).

    Can I just solder directly onto the battery terminals? With a copper
    wire. Should I use flux? Will this overheat the battery and/or blow it

    Thanks for any tips!
  2. Guest

    How did you open the battery pack without damaging it?
  3. Phil Allison

    Phil Allison Guest

    ** With decent soldering iron and some care - yes.

    ** Solid or stranded or tin plated - take your pick.

    ** What is found inside normal flux-cored solder is fine.

    ** No - not unless you take an inordinate amount of time to make the

    Warnings against soldering direct NiCd or NiMH cells are not founded on

    Manufacturers use steel tabs & spot welding as it is a much quicker method
    in mass production - but makes an inferior joint ( more resistance) than one
    made with short, solid copper wires and solder.

    ...... Phil
  4. DeanB

    DeanB Guest

    I had to snap off a cross-piece to get the battery out, but that does
    not seem to be an important piece of the construction. I can run the
    thing off a recharger ok without the cross pieces.
  5. neon


    Oct 21, 2006
    you can but then again what for by the time you are finished your battery are no good because of the heat. i don't know maybe that is why they are usualy spot weided
  6. I have opened up surplus NiMH batteries and removed the cells to
    rearrange them as a battery supply for a different device. I was able to
    solder them and my new battery pack worked. I didn't have any explosions
    when soldering but the pack started to leak after about 12 months of use
    with regular recharging.
    I threw the battery pack away when it started leaking. I don't know for
    sure if the resoldering of the cells caused the leaking. The original
    cells might have been a problem without the tampering. They were sold as

    I consider the effort and cost to be worth it. Less than two dollars of
    surplus batteries made a working, rechargable pack that would have cost
    me nearly sixty dollars!

  7. neon


    Oct 21, 2006
    HEAT destroy batteries burn off the electolite oh not right away but they are damaged for sure. ever bought any cheap battery in the swap meet they are totaly worthless sitting in the sun day after day. don't buy them.
    Last edited: Jun 22, 2008
  8. Bob Monsen

    Bob Monsen Guest

    Here is a tip. If you are soldering onto battery terminals, first melt a big
    blob of solder onto the end using a very hot iron. Then, remelt the solder
    and stick the wire into it. Works quite nicely, and doesn't overheat the
    battery too much.

    This works well for sets with tabs welded onto them too. Connecting between
    welded sets is much easier with 'the blob' technique.

    Spot welding is obviously better, but I don't have a spot welder...

    I agree about RC pack pricing, way too much for what you get.

    Another tip is that you can get shrink-wrap tubes to fit the battery pack
    into, which make them very nice looking, and holds them together well, so
    there isn't as much stress on the solder joints.

    Bob Monsen
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