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Efest Purple 40A 2600mAh 18650 Bench Test Results...only a 20A battery

Discussion in 'Batteries and Chargers' started by Mooch, Jan 21, 2016.

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  1. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    Efest told me that they would send samples of these to me for testing as soon as they were available. I haven't heard from them yet but cells were donated for the purposes of testing by /u/demoniccow9852 from ECR. Thank you! To prevent any confusion with the eGo-type "batteries", I use the term "cell" here to refer to a single 18650, 26650, etc.

    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 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. 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

    Bottom Line
    In my opinion this is a 20A 2600mAh battery. Just one set of continuous discharges at 30A, 35A, and 40A started damaging the cells. The appearance and performance of both cells were the same as the Sony VTC5. But Efest can change what cell they use under the wrap at any time, as they have done before. Both cells were verified as genuine.

    Continuous-Current Test Results

    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

    Comparison to Sony VTC5
    image.jpg image.jpg image.jpg

    • At 10A it reached a bit under 2500mAh. This is good performance for a 2600mAh-rated cell at 10A.
    • At 15A the temperature rose to 72°C. This is a few degrees below the average for a cell operating at its CDR and indicates we're still below its rated current level.
    • At 20A the temperature rose to 83°C. This is just at my upper limit for a cell operating at its CDR and indicates we're its rated current level.
    • At 25A the temperature rose to 95°C. This is way above the upper limit for a cell operating at its CDR.
    • Discharges at 30A and 35A brought the temperature up to 104°C and 112°C, respectively. Both of these discharges exceeded my safety limit of 100°C.
    • A discharge at 40A shows the voltage quickly collapsing down to the 2.8V cutoff. This is clearly not a 40A cell.
    • A second discharge at 20A shows a decrease in the voltage of the cell, indicating an increase in its internal resistance. This is damage caused by the extraordinarily high temperatures seen when discharged at 30A and 35A.
    • I am setting a CDR of 20A for this cell. While operating any cell near its rated maximum current causes damage to the cell, I would expect good 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 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.

    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

    26650 Safety Grades and Pulse Performance Data | E-Cigarette Forum
    • Like Like x 6
  2. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hundertwasser
    Thanks again Mooch.

    I have replaced the string of expletives, and the derogatory inferences regarding the suspect parentage of the board of directors at Efest I was planning of posting, with a picture of a kitten.

    • Like Like x 6
  3. MorpheusPA

    MorpheusPA Ultra Member ECF Veteran

    Sep 7, 2012
    Lehigh Valley, PA
    That's one ironic kitten.

    And surprise, another over-rated battery. No, really, this is my surprised face, I just had Botox so you might not be able to tell...
    • Like Like x 3
  4. KentA

    KentA Ultra Member Verified Member ECF Veteran

    May 5, 2015
    Adirondack Mountains
    Someday I expect a vaper with 1/2 a face will own Efest.
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