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Gpower Yellow/Black 20A 2500mAh 18650 Bench Test Results...accurately rated, poor performing

Discussion in 'Batteries and Chargers' started by Mooch, Nov 28, 2016.

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  1. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    May 13, 2015
    The two cells tested were donated by Gpower (Gpower Battery- Gpower 18650 26650 li ion battery and battery charge wholesale) for the purposes of testing. 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 image.jpeg

    Bottom Line
    This is an accurately rated, but poor performing, 20A cell. The 20A 2500mAh Samsung 25R delivers about 1300mAh at 20A down to 3.2V. This Gpower only delivers about 700mAh. And that was only after three cycles at moderate current levels to "break it in". Something that should never be required.

    This cell doesn't match the appearance or performance of any Samsung, Sony, LG, Panasonic, or Sanyo battery I have seen. It appears to be a China-manufactured cell and not a rewrap.

    While the cell does list the continuous current rating in very small print on the "back" of the wrap it has its useless "pulse" rating in huge print on the "front" of the wrap. I feel this is misleading and I encourage all battery companies that sell to the vaping community to only use the continuous current rating in large print or to use both, e.g., "20A/35A" for this cell.

    The 18650 ratings table has been updated to include this cell.

    Continuous-Current Test Results

    Pulse-Current Test Results
    image.png image.png

    • At 10A continuous it reached 2238mAh. This is almost average performance for a 2500mAh cell at 10A so I am rating it at 2500mAh.
    • At 15A continuous the temperature rose to 67°C. This is below the average temperature of a cell operating at its continuous discharge rating (CDR). This is an indication that we are operating below its true rating.
    • At 20A continuous the temperature rose to 77°C, just below the average temperature of a cell operating at its CDR. This is an indication that we are operating very near its true rating.
    • At 25A continuous the temperature only rose to 78°C but the voltage sag is huge. This is an indication that we are operating at above its true rating.
    • At 30A continuous the temperature rose to only 58°C but the voltage sag was so severe that the cell is essentially useless.
    • I am setting a CDR of 20A for this cell. While operating any cell near its rated maximum current level causes damage, I would expect good cycle life at 20A continuous.
    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
    • Like Like x 2
  2. Barkuti

    Barkuti Super Member ECF Veteran

    • Like Like x 1
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