MNKE IMR-26650 and Queen Battery QB26650 discharge test

thunderheart

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Hi guys! I've tested MNKE IMR-26650 3500mAh/30A and Queen Battery QB26650 5000mAh/20A.

The MNKE is a very strange cell without any datasheet available online. The manufacturer's websites (mymnke.com and mymnke.de) are down and i tried to find some info looking into Google Cache. The specs i found were more than strange - 3.8V nominal voltage, no discharge cut-off voltage, etc. After that i decided to use the specs provided by the supplier and/or guess the missing ones. Anyway, it's not being sold anymore.

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The cells were bought from Queen Battery about 5-6 months ago and weren't used until now.

As always, I've 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.
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I've used the v2.0 of my battery holder (with pure copper pads instead of steel ones)
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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 current mentioned in the datasheet to 4.2V (cut-off at 0.1A, which is the lowest supported by EBC-A20). Before each discharging or charging i've held a 1-1.5hrs pause. The environment temperature was 20-25°C (24-25°C to be honest).

Discharge cut-off voltage is 2.75V for QB26650 and i decided to use the same value for MNKE.

MNKE IMR-26650 3500mAh

This orange cell doesn't have any rating or marking on its wrapping. There seems to be a marking under the heat shrink but it's covered by the letters.
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Specs
Capacity: 3500mAh
Max continuous discharge current: 30A
Discharge cut-off: N/A (i've discharged down to 2.75V)
Standard charge current: N/A (i've charged at 0.5C/1.75A)
Max charge current: N/A
Charge end voltage: 4.2V

Test results:
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At 0.2C/0.7A it showed almost 3700mAh even being discharged down to 2.75V, not 2.5V. The 20A rate it held easily and showed 3472mAh (!!!) / 11.18Wh. This seems to be a great cell with only one drawback - its capacity.

Queen Battery QB26650 5000mAh

Queen Battery uses stickers on it's cells with quite detailed specs which is a good idea i think.
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Specs from the datasheet:
Capacity: 5000mAh
Max continuous discharge current: 20A
Discharge cut-off: 2.75V
Standard charge current: 2.5A
Max charge current: 5A
Charge end voltage: 4.2V

Test results:
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At 0.2C/1A, 5A and 10A the curves and the results are quite good, but i really didn't like the voltage sag at 20A. I think 20A is not the rate at which this cell should be discharged. The maximum current i'd recommend is 10A or maybe even 15A, but 20A is too much for this guy.

Side by side

I can't compare a 3500mAh cell with a 5000mAh one but sometimes it's interesting to try:)
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Just look at the 20A curves of both cells.

Verdict

Both cells have serious drawbacks which keep me back from recommending them.
QB26650 has 5Ah capacity, but does not so well at 20A.
MNKE shows very nice curves but 3500mAh for a 26650 cell is way too low. Combining two 18650 cells in parallel would result in grater capacity and higher discharge rate. I can't imagine any application in which this biggies can be preferred more than 18650s. No happy end, sorry guys:) I hope this test was useful and/or interesting to read.

The video version of this review:
[youtube]qDL7HHftgQc[/youtube]

P.S. this is my YouTube channel: www.youtube.com/thunderheartreviews It will be highly appreciated if you subscribe:) I need to reach 1000 subscribers to activate monetization and i need your support guys!
 
Great review thunderheart! It is to pleasure to read this informations even if 26650 format is out of my interest. I also like your battery test fixure, i was starting with similar one. There are some "handy" fixtures for small cylindrical cells on the market like this one goo.gl/p73NsR.
 
Excellent little test. Yeah, its rather sad that we dont have good 26650s available to the hobbyist these days huh? I've always wanted to build a pack with some, for the sake of simplicity, but its just not happenning. Seems like the 2070 is the next best thing.
 
Pajda, neptronix, thanks guys!
Queen Battery has stopped selling MNKE cells and they gonna update their line of QB-branded cells. I hope they will release a good 26650 cell too. They are very ambitious.

When i was upgrading my holder i wasn't able to find copper pads longer than 20mm. In fact it's the very minimum when something big like 26650 is held and you need to discharge it at 20A. Now i'm looking for longer pads and/or another ways of improving it. If you have any ideas - i'll be glad to read them :wink:
 
Did you look at the holder/fixture in my post above? https://www.aliexpress.com/item/Boutique-double-self-locking-aluminum-alloy-CNC-four-wire-battery-holder-fixture-BF-10-20A-for/32825000163.html?spm=2114.10010108.1000014.4.62854cadDSNYNe&traffic_analysisId=recommend_3035_null_null_null&scm=1007.13338.98466.000000000000000&pvid=a4e85867-335c-4509-b56d-9220be8807e0&tpp=1 This type of fixture has two advantages. First is that it has completely separated load current path and voltage measure tip. The second advantage is that one of the sides of this fixture have spring and so the cell can be easily removed/changed.

By the way, i thing that neptronix mean 21-70 or 21700 (20700 is dead at least for now). I found that Qeenbattery have in stock LG INR21700 H30 5000mAh cells, https://www.aliexpress.com/item/35pcs-lot-freight-free-to-USA-EU-21700-h30-INR21700H30-new-model-battery-h30-21700/32855890973.html Do not you know if it's possible to order from QB smaller amount? I usually need only 10pcs for life cycle testing.
 
Yes, i know that type of holders but to use them i'll have to desolder the wires from crocodile clips and solder them to the holder. After that i won't be able to connect lipos or mobile phone batteries to the tester. That's why i'm not buying those holders.

Pajda said:
Do not you know if it's possible to order from QB smaller amount? I usually need only 10pcs for life cycle testing.

I think they won't sell 10pcs, but you could mix battery types and take 10pcs of one type, 10pcs of another, etc... Try to send them an e-mail.
 
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