Efest Metallic Purple 20A 2900mAh 18650 Bench Test Results...a 20A battery, a lower grade HG2?

Discussion in 'Batteries and Chargers' started by Mooch, Jun 2, 2016.

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  1. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    These cells were donated for the purposes of testing by Efest. Thank you! 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.

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    Bottom Line
    This new Efest is accurately rated at 20A and 2900mAh and seems to rewrap a lower grade LG HG2. Its appearance is identical to the HG2 but its voltage is a bit lower and it has about 100mAh less capacity. This does not mean it's less safe to use! It's just a performance change and this Efest is accurately rated at 20A 2900mAh. This Efest still has the useless "pulse" rating in large lettering on the wrap but does list both the continuous and pulse ratings, a welcome change for Efest. These new metallic wrap 18650's ship with a plastic battery case for each pair of batteries.


    Continuous-Current Test Results
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    Pulsed-Current Test Results
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    Comments
    • At 10A continuous it reached about 2700mAh. This is average performance for a 2900mAh cell at 10A so I am rating this cell at 2900mAh.
    • At 15A continuous the temperature rose to 70°C. This is below the average temperature of a cell running at its continuous discharge rating (CDR).
    • At 20A continuous the temperature rose to 83°C. This is the upper limit for the temperature of a cell running at its CDR and is an indication that this is the cell's true rating. It's a typical temperature for a LG cell at its CDR. There's no sign of extra sag in the discharge curve that would indicate that the cell was being operated at above its rating.
    • At 25A continuous the temperature rose to 96°C. This is way above the average temperature of a cell running at its CDR and is an indication that we're above the cell's true rating.
    • I am setting a CDR of 20A for this cell. Operating at that level would bring the temperature of this cell up to the average of a LG cell operating at its CDR. While operating any cell near its rated maximum current level causes damage to the cell, I would expect decent cycle life from this cell at 20A continuous.
    • 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
    18350 Safety Grades and Pulse Performance Data | E-Cigarette Forum
    18650 Battery Ratings -- Picking a Safe Battery to Vape With | E-Cigarette Forum
    26650 Safety Grades and Pulse Performance Data | E-Cigarette Forum
     
    nilesong, gerrymi, puffon and 3 others like this.
  2. B2L

    B2L Vaping Master Verified Member ECF Veteran

    Supporting member
    Jan 14, 2012
    Jacksonville, FL
    That's a step in the right direction, seems your making a difference Mooch :thumb:
     
    KenD likes this.
  3. stjong

    stjong Unresolved Status

    Jun 2, 2016
    Sydney, Australia
    Thank you for the testing and comments.
     
    Mooch likes this.
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