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Thread: 18650 li-ion battery question

  1. #1
    Unenlightened
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    Default 18650 li-ion battery question

    Hi,
    I'm new to this forum and have a small question. I have a 18650 3.7v li-ion battery that measures 1.14v and will not charge. Should I consider that battery dead and just pitch it, or is there something I can do to it?

    Any help would be appreciated, thanks

  2. #2
    *Flashaholic* ChrisGarrett's Avatar
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    Default Re: 18650 li-ion battery question

    Quote Originally Posted by curious57 View Post
    Hi,
    I'm new to this forum and have a small question. I have a 18650 3.7v li-ion battery that measures 1.14v and will not charge. Should I consider that battery dead and just pitch it, or is there something I can do to it?

    Any help would be appreciated, thanks
    Yes. Depending on the chemistry and brand, we’re talking only a few dollars.

    Life is too short to be fiddling with questionable cells.

    Chris
    Convoy: S2, S2+, M1, M2, Fenix: P1D, PD32, HL30, ET: D25C Ti, SF: 6P, ZL: SC-600, Klarus: P2A, Jetbeam: BA-20, Icon: Rogue 1, L3: L10, Xeno: E03, ShiningBeam: I-Mini, Olight: i3s, SWM: D40A, M11R, V11R, Maglite: 6Ds, MMs, Solitaires, LaCrosse BC-700, Maha C-9000, XTAR VP2, MP1S, XP1, MC1+, WP2 II, NiteCore i4, v2.

  3. #3

    Default Re: 18650 li-ion battery question

    If you succeed in charging an 18650 cell that has been in an over-discharged state for a while, there's a risk it will explode. This doesn't seem worthwhile.
    Ceilingbounce - flashlight testing and runtime graphs for Android

  4. #4
    Flashaholic*
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    Default Re: 18650 li-ion battery question

    Download the spec-sheet for that cell, and see what the safety limits are. For example, the Samsung 30Q says it's okay to charge above 1.0v, as long as you do it slowly until it reaches 3.0v, then charge normally. But IMO, I'd keep an eye on it the entire charge, to make sure it doesn't overheat.

    If you don't have a charger that does initial slow-charging, you could wire it in parallel with a charged cell, and use a 100 ohm resistor in-between. Let those sit for several minutes, then disconnect and measure the cell's resting voltage. If it's above 3.0v, pop it in the charger.

    Of course, yes, the safest thing to do is throw it out and buy a new cell. 1.14v is pretty low, and likely either under the spec sheet's safety limit, or at the very edge.

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