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Efest Metallic Purple 7A 700mAh 18350 Bench Test Results.. a poor performing 4A battery

Discussion in 'Batteries and Chargers' started by Mooch, Jun 30, 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.

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

    Bottom Line
    This metallic wrap Efest cell is a poor performer and I rate it at 4A. It is much worse than its predecessor, the 7A 700mAh V2 purple cell and performs very much like the V1 version. Its capacity is good for its rating though and I rate it at 800mAh. It lists both the continuous and pulse ratings on the wrap, which could be a good thing, but the continuous rating is exaggerated and the pulse rating is meaningless without knowing the pulse width, duty cycle, and the criteria for setting the rating (temperature? run time? voltage sag?).

    Continuous-Current Test Results

    Pulsed-Current Test Results
    image.png image.png

    Comparison to the earlier V2 Purple 7A 700mAh Efest

    • At 3A continuous it reached about 720mAh. This is above average performance for a 700mAh cell at 3A so I am rating this cell at 800mAh.
    • At 6A continuous the temperature rose to 38°C but its voltage quickly dropped. Its capacity down to 3.2V is only about 50mAh. Yes, just 50mAh. This is clearly not a 7A cell.
    • At 9A continuous its voltage quickly collapsed.
    • I am setting a CDR of 4A for this cell. Operating at any higher than this causes the voltage to sag excessively. 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 4A 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
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