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Nitecore 40A 2600mAh 18650 Bench Test Results...ridiculous 40A rating, only 20A

Discussion in 'Batteries and Chargers' started by Mooch, May 14, 2017.

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  1. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    To prevent any confusion with the eGo-type "batteries", I use the term "cell" here to refer to a single 18350, 18650, 20700/21700, 26650, etc.

    While the test results are hard data, the conclusions and recommendations I make based on these tests are only my personal opinion based on my criteria for setting a rating. Carefully research any cell you are considering using before purchasing.

    Testing cells at their limits is dangerous and should never, ever, be attempted by anyone who has not thoroughly studied the dangers involved and how to minimize them.

    If the cell has only one current rating number on it, or if it says "max" then I have to assume that the company is stating that the cell can be discharged at that current level in any way, including continuously.

    IMG_5346.JPG IMG_5347.JPG IMG_5348.JPG IMG_5349.JPG IMG_5264.JPG


    Bottom Line
    This Nitecore is a 20A rewrapped cell with a useless and possibly dangerous "pulse" rating (see the Comments section).

    While this cell has an exaggerated 25A continuous rating in micro print on the wrap it also has a useless 40A "max pulse discharge" rating on the wrap too. It also features "40A" in a huge font which many people will use as the cell's rating when shopping or when a vendor displays it on their web site. For these reasons I feel the large "40A" rating, or any "pulse" or "max" rating, is misleading and shouldn't be used.

    If we vape with this battery above about 30A or so it can heat up to ridiculously high temperatures if there is a regulated mod malfunction or accidental button press in a mechanical mod. This could possibly force the battery to vent and leak/spray toxic organic solvents from the battery. I think vaper safety should be a priority when setting "pulse" ratings.

    The wrap is not the standard heat shrink plastic. It is self-adhesive and appears to be similar to Mylar. I do not know how durable it is compared to the wraps being used now by other companies.

    This cell says "IMR18650" on the wrap but it does not use IMR chemistry. It uses one of the INR chemistries.

    I was especially disappointed to see this cell's continuous current rating set at 25A by Nitecore. It is clearly set by Sony at 20A (see the VTC5 datasheet image below).

    I am rating this Nitecore at 20A and 2600mAh. Its maximum vaping amps (MVA) rating is 25A, limited by temperature. The ones I tested were rewrapped VTC5's. Their performance was essentially identical to the VTC5's I have here.

    The two cells that were tested were purchased by me from IMRBatteries.


    Continuous-Current Test Comparison to VTC5
    IMG_5350.PNG


    VTC5 Datasheet Specs
    IMG_5380.jpg


    Pulse-Current Test Results
    Pulse tests were not done since this is a rewrapped VTC5.


    Always Remember
    ⁃ There is no 18650 with a factory/manufacturer rating over 30A continuous.
    - There is no 3000mAh 18650 that can have a rating over 20A continuous.
    ⁃ There is no 3100mAh-3600mAh 18650 that can have a rating over 10A continuous.
    ⁃ There is no 18650 available to vapers that has a capacity rating over 3600mAh.


    Comments
    • At 10A continuous this cell delivered about 2475mAh. This is good performance for a 2600mAh rated cell so I am rating it at 2600mAh.
    • Pulse ratings are utterly and completely useless unless we know some things about how the ratings were set. There are no standards for a pulse rating. Without knowing the length of the pulse, the time between pulses, and the criteria used to set the rating (temperature? run time? voltage sag? a combination of these?) we can't compare one battery's pulse rating against another's. They're useless.
    • These "pulse" ratings can be dangerously high. While you might normally be able to vape at that high a level without too much risk, since the current is pulsed, these ratings don't take our safety into account in case of a mod malfunction or accidental button press. This can cause the battery to be discharged continuously, possibly causing it to vent (most likely not go into thermal runaway and burst though).
    To see how other cells have tested and how hard you can safely push them, check out these links: List of Battery Tests | E-Cigarette Forum
     
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