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ModWorx 38A 2100mAh 18650 Bench Test Results...only a 20A battery, collapses at 38A

Discussion in 'Batteries and Chargers' started by Mooch, Oct 18, 2015.

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  1. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    Tested at 10A-38A constant current and 30A-60A pulsed. These cells were purchased by me and used only for testing thanks to the incredible donations many of you made. 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 batteries 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 image.jpg

    Bottom Line
    In my opinion, this is only an average-to-good performing 20A continuous discharge current (CDR) cell, depending on which cell you look at. There was a larger than normal performance difference between the two cells I tested. Its capacity at 20A is either only 75% of the 2100mAh VTC4, or the same as the VTC4. When discharged at its continuous rating of 38A its voltage quickly collapsed.

    Continuous-Current Test Results

    Cell1 vs Cell2 Discharge Differences

    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

    ModWorx Web Site Discharge Graph
    The results for my two cells were very different from the graph at the ModWorx web site ( I am unable to explain this discrepancy. The ModWorx web site discharge plots look a lot like the ones for the VTC4, but idealized. Usually at the higher current discharges, 25A and 30A, there is a loss of capacity. But in the ModWorx graph the capacity keeps increasing. The ModWorx is not a VTC cell though. The ModWorx has a 4-prong top cap and the VTC's have a 3-prong top.

    • There was up to a 0.1V difference between the two cells I tested at the higher amp discharges. This is twice the normal cell-to-cell worst case difference I usually see.
    • At 10A it reached about 1950mAh. This is above average performance for a 2100mAh-rated cell at 10A.
    • At 15A the maximum temperature reached 66°C. This is way below the average temperature of a cell operating at its CDR.
    • At 20A the maximum temperature reached 76°C. This is just below the average for a cell operating at its CDR.
    • At 25A the temperature rose to 89°C. This is too high for a cell operating at its CDR.
    • At 30A the temperature rose to 99°C. This is almost at my 100°C safety limit and is way too high to operate a cell at.
    • At 35A and 38A the voltage quickly collapsed for both cells. This is not a 38A cell.
    • Five more 20A discharges showed that no additional damage was being done to the cell at this discharge current level.
    • I am setting a CDR of 20A for this cell. Its temperature is average at this level and the voltage is average to good, indicating that it's not being discharged at beyond its rating. While operating any cell near its rated maximum current causes damage to the cell, I would expect decent 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 30A-60A, 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:
    • Like Like x 6
  2. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hundertwasser
    Nice one Mooch. Keep taking them down bud.
    • Like Like x 2
  3. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    This one I was hoping was at least a 30A cell! Especially since they put a continuos rating on the wrap.
    • Like Like x 1
  4. sonicbomb

    sonicbomb Vaping Master Verified Member ECF Veteran

    Feb 17, 2015
    1187 Hundertwasser
    Charlatan, swindlers and mountebanks....
    • Like Like x 3
  5. State O' Flux

    State O' Flux Vaping Master Verified Member ECF Veteran

    Jul 17, 2013
    And another one bites the dust.

    Mountebanks? All the way back to the early 19th century... had to dig deep for that one, didn't ya' sonic. :thumbs:
    • Like Like x 2
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