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Makita Battery repair

Discussion in 'Electronics & Electrics' started by Pugs, Jun 9, 2020.

  1. Pugs

    Pugs Member

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    so i have a knock off Makita 18v Lithion battery that won't charge.. only bought last November.. the battery indicator says it dead flat ie won't come on at all.. is there a way to fix it?? and the legit mak charger has the red and green both flashing. (battery fault)
     
  2. merlin13

    merlin13 Member

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    It's either the charge/control board is borked, there's a broken wire/connection "somewhere" in it or worst case you may have a cell or two that have prematurely died.

    Or the charger is actually borked and the battery is fine. I assume you've got another battery nearby to test that theory?

    Else your other option is try charging it from a different source, like a suitable bench supply perhaps. Even kludge connections from a 19 volt laptop plugpack, you only want to see if it'll start to behave.

    Another bright thought though on such a young item - warranty perchance?...
     
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  3. slavewone

    slavewone Member

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    B.Mtns2774 Status:Unhappy
    The cheap batteries I’ve pulled apart have little to no circuitry to stop them going under voltage and I suspect that’s what’s has happened to you.
     
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  4. OP
    OP
    Pugs

    Pugs Member

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    charger is fine... it is just this one... the other battery i have is fine.. might be dead cells...
     
  5. power

    power Member

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    tried a warranty return?
     
  6. slavewone

    slavewone Member

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    The other issue I found was the lack of balancing circuitry.

    One of the cells isn’t necessarily dead, it’s just perhaps gone under voltage. If you can baby the voltage back up, you might get your battery back up.

    You should do your own research as I’ve only done it with my RC Lipos and put them on a nicd charge at very low charge rate to get them up to voltage and then more low charge rate before letting them settle for a few days and then taking them up. Permanent capacity loss was incurred.
     
  7. merlin13

    merlin13 Member

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    More than likely - I've got well-used 3 Name Brand cordless packs on the bench here that have been inflected with that symptom, as well as two decent cordless vacuums also in the queue for heart transplants...

    So pull yours to bits, apply Ye Goode Olde multimeter to each cell and see if any have dropped the bundle.
     
  8. MR CHILLED

    MR CHILLED D'oh!

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    Can you try jumpering for 15 mins with a good battery to get the charge up? I have a dead Milwaukee here I was going to give that a try on, I'm just not 100% sure which terminals are which.
     
    Last edited: Jun 15, 2020
  9. merlin13

    merlin13 Member

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    Mr Multimeter will usually show you which pins on the pack are the ones you can connect to. Or have been on the packs I've blundered about with... :)

    They're "usually" the ones symmetrically far apart as well. Like if you have 4 pins on the pack and the two on one side are showing the same positive voltage, then the inner one is "usually" the Sense line that the charger uses... or have been on the packs I've blundered about with... :)

    Else ask Mr Screwdriver for some help and have a looky inside.
     

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