Kdest White 40A 3100mAh 18650 Bench Test Results...preposterously overrated, absurd pulse rating

Discussion in 'Batteries and Chargers' started by Mooch, Dec 6, 2016.

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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, 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 discharging current" 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.

    image.jpeg image.jpeg image.jpeg image.jpeg image.jpeg


    Bottom Line
    This "40A" Kdest is just a rewrapped and overrated 20A cell that can boil water at only 30A continuous. It reaches a dangerous temperature at 35A continuous. Its "pulse" rating of 80A is absurd and brings me to the point of apoplexy just thinking about it. The first pulse at that level would drop the cell's voltage to under 2.5V....a less than useful voltage. Both of these Kdest cells were identical in performance and appearance to the Samsung 30Q.

    Kdest has printed "MADE IN KDEST" on the metal can which is interesting considering that this is a rewrapped Samsung cell.

    I am giving this cell a Maximum Vaping Amps (MVA) rating of 25A. The 18650 ratings table has been updated to include this cell. The two cells were purchased directly from Kdest (Kdest) for the purposes of testing.


    Continuous-Current Test Results
    image.png


    Pulse-Current Test Results
    Pulse testing was not done as this is a rewrapped 30Q. The test results for that cell are here: Samsung 30Q 20A 3000mAh 18650 Bench Retest Results...a great 20A/3000mAh battery!


    Comments
    • At 10A continuous it reached 2805mAh. This is average performance for a 3000mAh cell at 10A so I am rating it at 3000mAh.
    • At 15A continuous the temperature rose to 66°C. This is below the average temperature of a cell operating at its continuous discharge rating (CDR). This is an indication that we are operating below its true rating.
    • At 20A continuous the temperature rose to 77°C. This is just below the average temperature of a cell operating at its CDR and is an indication that we are operating at its true rating.
    • At 25A continuous the temperature rose to 91°C. This is way above the average temperature of a cell operating at its CDR and is an indication that we are operating at way above its true rating.
    • At 30A continuous the temperature rose to 104°C, above my 100°C safety limit.
    • At 35A continuous the temperature rose to 113°C, above my 110°C danger limit. The voltage sag is huge.
    • At 40A continuous, this battery's rating, it was essentially useless. This is obviously not a 40A cell.
    • I am setting a CDR of 20A for this cell. While operating any cell near its rated maximum current level causes damage, I would expect ok cycle life at 20A continuous.
    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
    https://www.e-cigarette-forum.com/f...afety-grades-and-pulse-performance-data.7566/
    https://www.e-cigarette-forum.com/f...des-picking-a-safe-battery-to-vape-with.7447/
    https://www.e-cigarette-forum.com/f...fety-grades-and-pulse-performance-data.7554//
     
    MikeyConti, sonicbomb and KenD like this.
  2. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hunterwasser
    Kdest to avoid these scumbag re-wraps like the plague.
     

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