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MXJO Yellow/Silver 35A 3000mAh 18650 Bench Retest Results...still an overrated battery

Discussion in 'Batteries and Chargers' started by Mooch, Dec 13, 2016.

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  1. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    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 image.jpeg


    Bottom Line
    This rewrapped cell has an exaggerated current rating and is the same as the older rewrapped yellow/silver "35A 3000mAh" MXJO. When discharged continuously at its claimed 35A rating an internal protection device is triggered at around 100°C, permanently disabling the cell. This helps protect it from venting but renders the cell useless and means it cannot be rated a 35A cell.

    WARNING: Do not assume that this internal protection device will prevent the cell from venting if you abuse this battery! It is not guaranteed to work and is only there as another possible layer of protection against using this cell at way above its rating.

    This new yellow/silver wrap has "Type 2" above "20A CDC" in small print on the "back" of the cell. I assume that means Continuous Discharge Current. While I applaud MXJO for putting this rating on the wrap, it's almost hidden and is essentially useless as very few people know what "CDC" means. In bold print on the front they have a meaningless 35A max or pulse rating with no mention of the continuous rating, which would be easy to add there. Even if they kept the continuous rating on the back of the cell they could have said "20A Continuous" or even "20A Cont." and used much larger lettering.

    These MXJO's are identical in appearance and performance to the 15A/3000mAh Samsung 30Q's, which I rated at 19A. This MXJO's maximum vaping amps (MVA) rating is 25A, limited by temperature rise. The 18650 ratings table has been updated to include this cell.

    I've seen posts claiming that this MXJO was lasting twice as long as an HG2 or 30Q before needing to be charged. It cannot last longer than the cell that it is a rewrap of, the Samsung 30Q. If MXJO switches to a lower grade cell, always a risk with rewrapped batteries, it could last less.

    The two cells tested were donated by Kai Chen from All Day Vapes (www.alldayvapes365.com). Thank you!


    Continuous-Current Test Results
    image.png


    Pulse-Current Test Results
    Pulse testing was not done because this is a Samsung 30Q: Samsung 30Q 20A 3000mAh 18650 Bench Retest Results


    Comments
    • At 10A continuous it reached 2809mAh. This is average performance for a 3000mAh cell at 10A so I am rating it at 3000mAh.
    • At 15A continuous the temperature rose to 64°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 82°C. This is a bit above the average temperature of a cell operating at its CDR and is an indication that we are operating near its true rating.
    • At 25A continuous the temperature rose to 92°C. This is way above the average temperature of a cell operating at its CDR and is an indication that we are operating at way above its true rating.
    • At 30A continuous the temperature rose to 104°C, above my 100°C safety limit. There is a lot of voltage sag.
    • At 35A continuous the temperature rose to 91°C and 111°C for the two cells I tested, incredibly high, and both cells failed permanently. The voltage sag was huge.
    • I am setting a CDR of 19A for this cell. While operating any cell near its rated maximum current level causes damage, I would expect ok cycle life at 19A 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
    https://www.e-cigarette-forum.com/forum/blog-entry/18350-safety-grades-and-pulse-performance-data.7566/
    https://www.e-cigarette-forum.com/forum/blog-entry/18650-safety-grades-picking-a-safe-battery-to-vape-with.7447/
    https://www.e-cigarette-forum.com/forum/blog-entry/26650-safety-grades-and-pulse-performance-data.7554//
     
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  2. bullzeyesh00ter

    bullzeyesh00ter New Member

    Dec 18, 2016
    Hey Mooch i am a relatively new vaper and had heard a lot of good things about you from Grimmgreen this is my first time ever on on a forum but my question to you is i just bought these mxjo 35a 18650s for my rx200s i asked the guy at my local vape shop if they were ok to use with this mod. He told me that amp limit doesn't really matter in regulated mods its more for mech mods. So i bought them and got home then read your blog Unfortunately i was disappointed that they were kinda iffy according to you I usually build between .3 and .7 ohms either single or dual coil do you think will be ok or do you think its too dangerous. Thank you for all that you do.
    Much Respect,
    bullzeyesh00ter
     
  3. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    Welcome to ECF!
    Coil resistance doesn't matter in a regulated mod. What is the highest power level you are vaping at?
     
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  4. bullzeyesh00ter

    bullzeyesh00ter New Member

    Dec 18, 2016
    Havnt used them yet but i usually vape no more than 80 watts but usally stay around 50 - 70 watts
     
  5. Mooch

    Mooch Electron Wrangler Verified Member ECF Veteran

    Supporting member
    May 13, 2015
    So you're around 25W per battery, easily handled by those MXJO's.
    If those batteries are the 3000mAh ones they are Samsung 30Q rewraps and can handle about 60W each, 180W in a RX200.
     
    • Like Like x 1
  6. bullzeyesh00ter

    bullzeyesh00ter New Member

    Dec 18, 2016
    Thank you for the help Mooch i really appreciate it. Also thanks for all you do for the community!
     
    • Like Like x 1
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