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Thread: Resetting Keeppower with Bench Power Supply

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    Flashaholic* LiftdT4R's Avatar
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    Default Resetting Keeppower with Bench Power Supply

    Hey guys, I have a 6 month old 26650 Keepower that won't register on my chargers and has 0V according to y multi meter. I tried putting 100ma at 3V on it for a minute or so on my bench power supply but it still had 0V. Is the battery junk? Any tips? Thanks guys!

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    Flashaholic* RetroTechie's Avatar
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    Default Re: Resetting Keeppower with Bench Power Supply

    Protected or naked cell?

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    Flashaholic* LiftdT4R's Avatar
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    Default Re: Resetting Keeppower with Bench Power Supply

    Protected

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    *Flashaholic* ChrisGarrett's Avatar
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    Default Re: Resetting Keeppower with Bench Power Supply

    Quote Originally Posted by LiftdT4R View Post
    Protected
    Put it nose to nose with a fully charged li-ion and short the negative contacts with an unfolded paperclip, or small jumper.

    Chris
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    Flashaholic* RetroTechie's Avatar
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    Default Re: Resetting Keeppower with Bench Power Supply

    Looks like protection circuit tripped. I'd try with a higher voltage, and don't be afraid to put some current through it but keep it short. Say 4V, 1A current limit. Or use another Li-ion to 'jump start' this one. Only a second or so should do.

    If that doesn't work: regular charging voltage (4.2V), but with a high-value series resistor (~1K ohm) to limit charging current to a few mA. Leave that for a couple of hours.

    If that also doesn't work: remove protection circuit & re-rewrap the cell.

    In any case: as soon as battery shows any signs of life, remove external power & check resting voltage. If the cell sat in storage at a low voltage (<2.5V or so) for too long, it could be unsafe to put back into service, have increased self-discharge, or lost a good deal of its capacity. Charge at a low current (0.01C or so) until cell is back into >3V range.

    Oh and just to be sure: before doing anything, check multimeter against other voltage source(s). When you're satisfied multimeter works correct, don't mess with its range settings before measuring your 26650 cell.

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    Flashaholic* DIWdiver's Avatar
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    Default Re: Resetting Keeppower with Bench Power Supply

    If you actually got 100 mA into the battery, and it did not recover, it's junk. OTOH if you only put 3.0V on it and it didn't take any current, it could still be perfectly fine.

    You should put at least 4.2V on the cell and/or verify it took a bit of charging current before binning it. You should also verify it charged to at least 3.0V.

    You should also be aware that a LiIon battery that's been deeply discharged for more than a short time becomes dangerous. I will not discuss specifics. Do your own research if this is a concern for you.

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    Flashaholic* LiftdT4R's Avatar
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    Default Re: Resetting Keeppower with Bench Power Supply

    Quote Originally Posted by DIWdiver View Post
    If you actually got 100 mA into the battery, and it did not recover, it's junk. OTOH if you only put 3.0V on it and it didn't take any current, it could still be perfectly fine.

    You should put at least 4.2V on the cell and/or verify it took a bit of charging current before binning it. You should also verify it charged to at least 3.0V.

    You should also be aware that a LiIon battery that's been deeply discharged for more than a short time becomes dangerous. I will not discuss specifics. Do your own research if this is a concern for you.
    Thanks, it would not take any current. My bench supply stayed at 0 the entire time.

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    Enlightened Katherine Alicia's Avatar
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    Default Re: Resetting Keeppower with Bench Power Supply

    put a small nick in the plastic wrap until you can see the metal underneath, then test with your multimeter using that freshly exposed metal as the negative. this will tell you where your battery`s really at voltage wise, assuming that it`s a bottom of the cell protection circuit, and not the sort that fit on the top.

    Personally if the cell itself is still good I`d strip it down and remove the protection, re-wrap, charge it, and then fit another protection circuit to it.

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    Flashaholic* LiftdT4R's Avatar
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    Default Re: Resetting Keeppower with Bench Power Supply

    Quote Originally Posted by Katherine Alicia View Post
    put a small nick in the plastic wrap until you can see the metal underneath, then test with your multimeter using that freshly exposed metal as the negative. this will tell you where your battery`s really at voltage wise, assuming that it`s a bottom of the cell protection circuit, and not the sort that fit on the top.

    Personally if the cell itself is still good I`d strip it down and remove the protection, re-wrap, charge it, and then fit another protection circuit to it.
    Thanks, will give that a shot later today!

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    Flashaholic* DIWdiver's Avatar
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    Default Re: Resetting Keeppower with Bench Power Supply

    Quote Originally Posted by LiftdT4R View Post
    Thanks, it would not take any current. My bench supply stayed at 0 the entire time.
    If it too no current at 3v, that means nothing. If it takes no current at 4.2V that means either the cell or the protection circuit is bad. Or possibly a bad connection. Katherne Alicia's suggestion is also a good one.

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