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Thread: Maximum current on non protected 18650's

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    Default Maximum current on non protected 18650's

    On a 2100ma 18650, non protected cell, can I safely draw a constant 3 amps from it, or it may explode ? or that 2100ma rating on it is the max current to use ?
    Also, if that same cell was a protected one, what would the upper current be to trip it ? Approx.

    Thanks

  2. #2
    *Flashaholic* HKJ's Avatar
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    Default Re: Maximum current on non protected 18650's

    Quote Originally Posted by videoman View Post
    On a 2100ma 18650, non protected cell, can I safely draw a constant 3 amps from it, or it may explode ? or that 2100ma rating on it is the max current to use ?
    Also, if that same cell was a protected one, what would the upper current be to trip it ? Approx.
    That depends on the actual cell used, i.e. try searching for the datasheet. Today a 2100 mAh cell will often be a high current cell and be able to handle 10 ampere draw.
    Protection limits are from about 30% to 100% above the rated maximum current on the batteries I have tested.
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    Default Re: Maximum current on non protected 18650's

    Quote Originally Posted by HKJ View Post
    That depends on the actual cell used, i.e. try searching for the datasheet. Today a 2100 mAh cell will often be a high current cell and be able to handle 10 ampere draw.
    Protection limits are from about 30% to 100% above the rated maximum current on the batteries I have tested.
    Who say so, unless its an IMR or maybe Lifepo4/Li-po, otherwise the cell gets heat up easily then fireworks come out
    Not ALL Li-ion supports over-2C "continuous" current draw
    Last edited by jh333233; 01-06-2012 at 02:16 AM. Reason: Added "continuous"

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    Flashaholic* samgab's Avatar
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    Default Re: Maximum current on non protected 18650's

    As there has been no actual smoke or fire, this thread probably belongs one level up, just in "Flashlight Electronics - Batteries Included" rather than this topic area, FYI.
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    Default Re: Maximum current on non protected 18650's

    2.1Ah 18650 cell can safely deliver 3A because its below "2 times Capacity" which is 4.2A
    Lifepo4 and Li-Po have a larger max continuous discharge rate but im not sure about it
    For IMR its 10C, which means it can be drained completely in 6 minutes without causing trouble

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    *Flashaholic* HKJ's Avatar
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    Default Re: Maximum current on non protected 18650's

    Quote Originally Posted by jh333233 View Post
    Who say so, unless its an IMR or maybe Lifepo4/Li-po, otherwise the cell gets heat up easily then fireworks come out
    Not ALL Li-ion supports over-2C "continuous" current draw
    The last two LiCoO2 cell I have received both supported 10A current drain.
    When designing a cell it can be made for high capacity (Today that is 2600, 2900, 3100 mAh) or high current (The lower capacities). For older cell design the capacity/current change will be at a lower capacity value.
    But as I also wrote, search for a data sheet.
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    Flashaholic* Changchung's Avatar
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    Default

    Very good info here...

    I just buy some panasonic 3100mAh protected, I wondering if exist different kind of quality of protected pcb?

    If I drive 4 18650 protected in serie can this damage the pcb?

    I just want to use this thread to find a answer because I think is almost the same thing...

    Thanks

    I forget, I just can find lifepo4 in 1000mha max, I am right or exist highest capacity for this batteries???


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    Flashaholic* yifu's Avatar
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    Default Re: Maximum current on non protected 18650's

    Generally, the maximum discharge rate for LiCoCl cells is 2C, double the cell's capacity in amp hours. For LiMn chemistries, this increases to around 10C or to 20C for LiFePo cells.

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    Flashaholic* jasonck08's Avatar
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    Default Re: Maximum current on non protected 18650's

    Quote Originally Posted by videoman View Post
    On a 2100ma 18650, non protected cell, can I safely draw a constant 3 amps from it, or it may explode ? or that 2100ma rating on it is the max current to use ?
    Also, if that same cell was a protected one, what would the upper current be to trip it ? Approx.

    Thanks
    Almost all quality LiCoO2 cells will have a max disharge rate of 1.5-2C. Some newer "mid-current" cells that were released within the last year support currents up to 10A and have capacities in the 2000-2250mAh range. When in doubt consult the spec sheets.

    Quote Originally Posted by HKJ View Post
    The last two LiCoO2 cell I have received both supported 10A current drain.
    When designing a cell it can be made for high capacity (Today that is 2600, 2900, 3100 mAh) or high current (The lower capacities). For older cell design the capacity/current change will be at a lower capacity value.
    But as I also wrote, search for a data sheet.
    10A cells are not going to be pure LiCoO2. All the ones I have seen have some Nickel and Manganese in them.

  10. #10

    Default Re: Maximum current on non protected 18650's

    Question:

    Say a 18650 cell is 2000mah and can draw 2C (4 amp). If I have two of these 18650 cells in parallel, can I double the amp draw? (8 amp?) And three in parallel can take 12 amp draw etc.?

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    Default Re: Maximum current on non protected 18650's

    Hello Kje,

    That is correct.

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    Most batteries don't die - they are tortured to near death, then murdered...

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    Flashaholic LAMPARITA's Avatar
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    Default Re: Maximum current on non protected 18650's

    I was wondering how many minutes or hours of running time a 2600mAh 18650 battery will outlast a 18650 2300mAh? After all, the difference is only 300mAh.
    "Remember, no one can make you feel inferior without your consent"

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    *Flashaholic* HKJ's Avatar
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    Default Re: Maximum current on non protected 18650's

    Quote Originally Posted by LAMPARITA View Post
    I was wondering how many minutes or hours of running time a 2600mAh 18650 battery will outlast a 18650 2300mAh? After all, the difference is only 300mAh.
    A first estimate is to look at the difference in percent, but this may not work in real life. Some batteries can keep a high voltage most of the time and depending on the load it may give a high or low load to the battery, compared to the load when the voltage is dropped.
    I.e. the load on the battery will not necessary be equivalent with different types of batteries and this may hide the difference or exaggerate the difference.
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