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SANYO UR18650ZK - low-priced 2500mAh cell's capacity test

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    SANYO UR18650ZK - low-priced 2500mAh cell's capacity test

    Sanyo UR18650ZK is a low-priced low-drain 18650 Li-ion cell which is made by Sanyo in Nanjing, China. It's one of those cells without any datasheet available across the web.

    The battery was bought from my reliable supplier (Queen Battery) and tested with ZKETECH EBC-A20 and a self-made battery holder. It's a PC-connected battery tester supporting 4-wire measuring and discharging at up to 20A.

    I've used version 3.0 of my battery holder based on 0.5mm thick pure copper terminals

    I've followed all the prescriptions of the IEC61960-2003 standard concerning battery's capacity measurement. Before each discharging cycle each battery was charged at standard charge current mentioned in its datasheet to charge end voltage. Before each discharging or charging i've held a 1-1.5hrs pause. The environment temperature was 23.0-24.5°C. To be sure in results i've done each test minimum twice (usually 3-4 times).

    SANYO UR18650ZK

    As always Sanyo didn't print the marking on the heat shrink tube but embossed it in a way that it becomes hardly readable.

    The cell is marked as SANYO Z UR18650ZK V23A.

    As far as this guy doesn't have any datasheet, i had to use the following values for testing:
    Capacity: 2500mAh
    Standard charge current: 1.25A (0.5C)
    Charge end voltage: 4.2V
    Charge cut-off current: 100mA
    Max. discharge current mentioned by suppliers: 5A (2C)
    Discharge cut-off voltage: 2.5V

    The measured DC IR of fully charged cell at 2500mA was 38±2.5mΩ
    My cell's weight was 46g

    Usually Li-ion cells reach their maximum capacity at the first or second round of the test, then it starts to decline. UR18650ZK demonstrated an unusual behavior, because it's capacity was higher and higher with each round. I tested it 7 times at each discharge rate and at 0.5A the capacity kept on rising up to the end. At 2A it started to decline from 6th round and at 5A - from 5th round. It's a good sign which makes me suggest that the cell gonna stay close to the rated capacity for a long time. Let's look at the results:

    At 0.2C or 0.5A UR18650ZK's capacity was noticeably higher than 2500mAh - 2672mAh. Even at 5A discharge it was just a bit lower than 2500mAh - 2482mAh. I liked this cell a lot. All i need is some info on its cycle life performance...

    Here is the video version of this review:

    Check out my YouTube channel for batteries, chargers and other stuff reviews.
    I've launched my blog where you can find all my reviews in one place. Every new test/review will be first published on YouTube and in the blog. I'll be happy to see new subscribers, comments, suggestions and just your thoughts.