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Efest Purple 20A 3500mAh 18650 Bench Test Results...just another rewrapped 10A battery

Discussion in 'Batteries and Chargers' started by Mooch, Apr 7, 2016.

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  1. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    These cells were purchased by me for the purpose of testing. 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.

    A note regarding current ratings and my testing
    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

    Bottom Line
    This Efest is a rewrap, identical in appearance and performance to the Panasonic 10A/3300mAh NCR18650GA. Both the Efest's current and capacity ratings are exaggerated. At 20A continuous this cell gets hot enough to boil water, 111°C.

    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 of, the battery if there is a malfunction or accidental pressing of your mechanical mod's button.
    image.jpeg image.jpeg

    Efest Purple 20A 3500mAh vs Panasonic NCR18650GA

    • At 10A continuous it reached about 3100mAh. This is average performance for a 3300mAh-rated cell operating at 10A so I am rating this cell at 3300mAh.
    • At 10A continuous its temperature rose to 70°C. This is a few degrees below the average temperature for a cell operating at its continuous discharge rating (CDR).
    • At 15A continuous the temperature rose to 91°C. This is significantly above the average temperature for a cell operating at its CDR.
    • At 20A continuous the temperature rose to 111°C. This is a dangerously high temperature, way above my safety cutoff of 100°C. This is clearly not a 20A battery.
    • 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:
    18650 Battery Ratings -- Picking a Safe Battery to Vape With | E-Cigarette Forum
    26650 Safety Grades and Pulse Performance Data | E-Cigarette Forum
    • Like Like x 6
    • Agree Agree x 1
  2. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hundertwasser
    • Like Like x 3
  3. bizzyb0t

    bizzyb0t Super Member ECF Veteran

    Mar 13, 2009
    Denver CO, USA
    Efest just can't be trusted. Do they just not give a frak about safety?
    • Like Like x 2
  4. Scy123

    Scy123 Super Member Verified Member ECF Veteran

    Aug 10, 2014
    Wow this is going too far.
    • Like Like x 3
  5. jpasint

    jpasint Super Member Verified Member ECF Veteran

    Agreed. Its reviews like this that make me happy that with the wattage that I vape at I'm only drawing about 2 amps of current from my 18650's.

    Companies like this are dangerous to the vaping industry.
    People could be seriously injured or even killed using this battery at its stated rating.
  6. sig-cmt

    sig-cmt Ultra Member

    Sep 28, 2015
    HoustΩn, TX
    Gong farmer...I learned a new term today :)
    • Like Like x 3
  7. KenD

    KenD Vaping Master ECF Veteran

    Aug 20, 2013
    Stockholm, Sweden
    Yeah, me too. Should be useful in the future :)

    Sent from my M7_PLUS using Tapatalk
    • Like Like x 1
  8. budynbuick

    budynbuick Super Member Verified Member ECF Veteran

    Dec 18, 2012
    Yes. I wonder what with the popularity of these cells, why there have been no reported failures? Or have there? Also,,why has this not been revealed sooner? Must be cause of the perty wrapper lol.
  9. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    If a battery dies early most people just toss it and not buy that model again. They're not going to vent unless severely abused and the chance of it going into thermal runaway is almost zero unless short-circuited. And even then it's hard to do.

    There aren't a lot testers out there who try to figure out what was rewrapped for these batteries. By the time someone might figure it out that battery has been replaced by a different one.
    • Like Like x 3
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