Restart/recharge dead lithium-ion batteries?

Discussion in 'Bad Dog Cafe' started by wabashslim, Jun 20, 2021.

  1. wabashslim

    wabashslim Friend of Leo's

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    My Black & Decker hand vacuum started slowing down sooner after about 2 years of very light use. It was always kept on its charging port. Being unfamiliar with these batteries I thought I should probably run it down all the way and charge it up from scratch. Well I ran it down alright, till it quit, but when I put it on the charger it just rapidly flashes all 3 of its charging lights at me without ever going into charging mode.
    I let it do that for up to an hour with no change. So now I don't know if the batteries are really killed or if this is some protection circuit function. B&D's website is no help, googling lithium-ion tells me these batteries don't like being fully discharged, that trying to bring them back involves expensive, specialized equipment and techniques. Ideas??
     
  2. stormsedge

    stormsedge Friend of Leo's

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    Take it to one of the battery specialty stores...they might know what to do.
     
  3. Frodebro

    Frodebro Doctor of Teleocity Ad Free Member

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    You can probably find replacement battery cells online, which would be your best bet.
     
  4. dogmeat

    dogmeat Friend of Leo's

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    the battery needs a minimum voltage before the charger will accept it. I have a variable power supply, so I use that. find the 2 pins that are battery plus & minus and determine polarity. hook up the supply and increase voltage from zero up to whatever it takes to get some current to flow (1/10 the C rate minimum at first, the .5C rate is pretty safe for a short run)(C is battery amp hour capacity). you may need a higher voltage than the battery says it is to get that to happen. if the current jumps up, then quickly reduces that means it's accepting the charge and will probably recover. increase the voltage to get back the 1/10C rate, and repeat until you can measure normal voltage on the battery (or close) then put it on the charger. if, on the other hand, the applied voltage is high and the current does not drop it probably has a bad or weak cell.

    it shouldn't take more than a few minutes to know the answer. if the battery gets warm... get it outside

    don't charge it with anything other than the OEM charger. they have safeties built in... thats why it refused to charge the battery in the first place. the process I described is an override & just to get the battery up to where the charger will take over. I think most chargers have temp sensing now anyway but if it got warm, let it cool.

    there is a ton of energy in these batteries and if it breaks down and catches fire it all over
     
    Last edited: Jun 20, 2021
  5. Gunny

    Gunny Tele-Holic

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    I agree with Dogmeat. I had the same symptoms with a Ryobi grass trimmer. By briefly 'boosting' a couple of cells for a short time, the battery reached enough terminal voltage to trigger the charger back into action properly. I also boosted a guy's ION Bluetooth auxiliary speaker/amp battery with success. It wasn't charging like it should.
     
  6. wabashslim

    wabashslim Friend of Leo's

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    I wondered if the battery just needed a kick in the 'trodes to wake it up. But these types tend to create terrifying headlines so I wondered how wise it was to subject it to my usual probing.

    I don't know how much of the charging circuitry is in the vacuum itself or the charging base that hangs on the wall. The vacuum just has two unmarked little contacts. But it does have screws all around...

    I just now noticed that after setting disconnected overnight when I hit the ON button the lights flashed once for an instant, but not again. I'll let it sit again and then set it on the charger to see how it goes.
     
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