X2 Power 37.5A 2400mAh 18650 Bench Test Results...only an average 20A battery, damaged at 25A

Discussion in 'Batteries and Chargers' started by Mooch, Nov 22, 2015.

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  1. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    Tested at 10A-37.5A constant current and 30A-50A pulsed. These cells were purchased by me and used only for testing thanks to the incredible donations many of you made. To prevent any confusion with the eGo-type "batteries", I use the term "cell" here to refer to a single 18650, 26650, etc.


    Disclaimer
    The statements, conclusions, and recommendations I make based on these tests are only my personal opinion. Carefully research any battery you are considering using before purchasing.

    Testing batteries 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. My safety precautions are the ones I have elected to take and you should not assume they will protect you if you attempt to do any testing. Do the research and create your own testing methods and safety precautions.

    image.jpg image.jpg image.jpg image.jpg image.jpg image.jpg image.jpg

    A note regarding current ratings and my testing
    If the cell has only one current rating on it then I have to assume that the company is stating that the cell can be discharged at that current level in any way, including continuous. Otherwise they would have listed the current rating with two numbers as other companies have done. Or they would have labeled the rating on the wrap as "pulse" or "burst". Battery buyers should not have to hunt down what the number on the wrap means. I will be testing cells at the rating listed on the wrap and pointing out when they fail to meet that listed rating.


    Bottom Line
    In my opinion, this is an average performing 20A continuous discharge current (CDR) cell. Three discharges at only 25A damaged the cell and caused a significant decrease in performance.


    Continuous-Current Test Results
    image.jpg


    Pulsed-Current Test Results
    These tests are done to show the performance of the cell at higher pulsed current levels. If you are running your mod at these levels be aware that you risk overheating, and possibly venting, the battery if there is a malfunction or accidental pressing of your mechanical mod's button.
    image.jpg image.jpg


    Comments
    • At 10A it reached about 2170mAh. This is average performance for a 2400mAh-rated cell at 10A.
    • At 15A the maximum temperature reached 67°C. This is below the average temperature of a cell operating at its continuous discharge rating (CDR).
    • At 20A the maximum temperature reached 82°C. This is above the average for a cell operating at its CDR but just within the range of acceptable values. The capacity was 17% less than a Samsung 25R at 20A.
    • At 25A the temperature rose to 96°C. This is too high for a cell operating at its CDR and is very close to my safety limit of 100°C.
    • Discharges at 30A and 37.5A showed huge voltage sag and loss of capacity. This is clearly not a 37.5A cell.
    • Two more 20A discharges showed that no additional damage was being done to the cell at this discharge current level other than what occurs when running a cell at its CDR.
    • Two more 25A discharges show clear damage to the cell. I do not recommend operating this cell above 20A continuous.
    • I am setting a CDR of 20A for this cell. Its temperature is high but acceptable. While operating any cell near its rated maximum current causes damage to the cell, I would expect decent cycle life from this cell at 20A.
    • I have included pulsed discharges but I haven't set pass/fail standards for pulse testing yet. The discharges were done at 30A-60A, 5sec on/30sec off, down to 2.5V. One chart shows the entire discharge at each level. The other chart is zoomed in to show the first 5 minutes to make it easier to see the voltage sag at different current levels.
    • I was only able to pulse it up to 50A before the voltage sag approached 2.5V. The better 20A cells don't do this until they are pulsed at 60A. I would consider its 37.5A rating to be a pulse rating.

    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
    18650 Safety Grades -- Picking a Safe Battery to Vape With | E-Cigarette Forum
     
    liblue1, sonicbomb, Woofer and 5 others like this.
  2. Cheeze941

    Cheeze941 New Member

    Feb 6, 2016
    does it matter what your voltage drain rate is during the amperage drain, and if so what voltage drain are you putting on these batteries during your testing?
     
  3. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    Welcome to ECF!

    The voltage drops on its own as a result of the current draining out charge from the battery. All I do for testing is apply a load to the battery.
     
  4. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hunterwasser
    X2 (sounds fancy :)) Power (oh dear here we go) 37.5A (guffaw) 2400mAh (no no, no, no...)
     
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