Low Voltage Li-on battey 18650

Discussion in 'Power Electronics' started by Chan777, Sep 12, 2018.

  1. Chan777

    Chan777

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    i have 6 cell 18650 from a dead laptop. the four cell have each 2.7 volts, and two have 2.2 volts.. is it possible that 2.7 volts can still be use?

    tnx
     
    Last edited by a moderator: Sep 14, 2018
    Chan777, Sep 12, 2018
    #1
  2. Chan777

    HellasTechn

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    I do not think so... The 18650 are considered full empty at 3.6V and full charged at 4.15~4.20.
    Chances are that those cells are either completely unusable or storage capacity has seriously diminished if they where sitting around at such low voltage for long time.
    In my opinion the best case scenario for you is that your cells have lost most of their capacity to store energy.
     
    HellasTechn, Sep 12, 2018
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  3. Chan777

    Hopup

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    Yeah dont try to use them, cells can be dangerous when under minimum voltage.
     
    Hopup, Sep 12, 2018
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  4. Chan777

    dave9

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    3.6V is the nominal voltage rating, not full empty which is closer to 3.0V. Many manufacturers specify even lower than that, around 2.x V (2.5V, etc).

    If you can determine the manufacturer then get the datasheet to see the minimum safe discharge voltage they specify. The 2.7V cells are "probably" fine, and the 2.2V more likely not fine, but I would put them in a charger inside a metal container or away from anything flammable like on a concrete floor for the first few charge cycles to see if they're behaving normally.
     
    dave9, Sep 12, 2018
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  5. Chan777

    HellasTechn

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    I agree with what you say but still i would not use them.

    We are missing a key factor here. How long have they been sitting arround like that ?
     
    HellasTechn, Sep 13, 2018
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  6. Chan777

    Chan777

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    about a year and a half on my broken laptop
     
    Chan777, Sep 14, 2018
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  7. Chan777

    HellasTechn

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    I would not trust them.
    Still you can charge them up to about 4,18V and put them to use. thay may still be ok for a flashlight or something like that but dont expect too much.
    Make sure you use a good quality 18650 LiPo battery charger. These cells can explode if overcharged.
     
    HellasTechn, Sep 15, 2018
    #7
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