Modest test of LiitoKala Lii-40A 21700 cells, “interesting” results

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Barkuti
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Modest test of LiitoKala Lii-40A 21700 cells, “interesting” results

Received these cells past 13th of April, purchased from the “famous” AliExpress store number 217753 (dubbed liitokala Official Store). Received two slightly different Facepalm cells in wrinkled yellow wraps.

 

 

Measured cell dimensions with cheap 0.1 mm accuracy (?) Aneng caliper:

  1. Ø21.2 - 21.3 mm and 70.4 mm long for the ringed bottom cell.
  2. Ø21.2 - 21.3 mm and 70.6 mm long for the flat bottom cell.

I charged the cells with the help of my modified Lii-100B, with filed Wink rail tops:

 

 

Discharge test done at 1 and 5 A in my EBD-M05 battery tester, at 19 - 20 °C. Drum roll:

 

 

Wellp, the evidence can clearly be seen. There is a slight internal resistance and capacity difference. Ringed bottom cell is probably a 3C continuous cell, and the higher capacity flat bottom one maybe a little lower.

Where do these come from? Their tops are very lookalike, so same OEM nearly for sure. But other than this… ¯\_(ツ)_/¯

Comments:

Bought the cells very cheap, €5.32 for a pair. Not very professional to use different cells under the same wrap, this is what we get with shoddy rewrappers.

Edited to say that, after checking again HKJ's Lii-40A test values in his comparator, I can clearly see he obtains better values than me in his setup. I know they're not the same cells, but I have obtained curves from similar cells to those tested by Henrik and I can see my test setup causes a higher voltage drop in the cells with the same theoretical current load. I wonder if room temperature is the key here. 

Mon, 04/20/2020 - 00:26

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Edited by: Barkuti on 10/18/2020 - 15:37
Blggg
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Appreciated.

Helios azimuth
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I have never purchased anything from AliExpress. Thanks for the review.

hank
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Quote:
Not very professional to use different cells under the same wrap

important misbehavior to point out, thank you.

Sunnysunsun
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Have they got any 18650s with over 3000mAh capacity but terrible voltage sag? I’m looking for ways to make my HL03 more efficient and less hot. I’m thinking if I use a cell with a lot of voltage sag, less of it will be turned into heat by the 7135s.

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It gets even better. I have one “flat bottom” 4000mAh ordered few months ago. It has such diameter, that it does not fit any of the earlier Convoy 21700 lights. The newly received “ring bottom” is thinner, so that it fits properly. It has the same diameter as the 5000mAh version, which was known to be on the thinner side, fitting Convoys properly.

I will run a capacity test on them soon, but for now these LiitoKalas 21700 cells are pure gamble.

Barkuti
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Yes Sunnysunsun, along with other sellers alike they sell BAK 18650-34T battery cells with spurious NCR18650B wraps. The funny thing is that the BAK 34T is a better cell than the Panasonic NCR-B. I also received a 4-pack of these recently, with on average ≈3230 mAh in my capacity underestimating Lii-500 analyzing charger at 0.5 A, this means they would do ≈3300 mAh at the same current and cut-off (0.5 A / 2.8 V) in my EBD-M05.

I bought the cells with a box in this sale ad. There are plenty of other options if you search for NCR18650B in their store or abroad in AliExpress. I must also say that the wraps of my “good but fake” NCR18650Bs are really smooth and good looking, without wrinkles. This means the guys scoundrels who are doing the rewrapping business have some real battery wrapping machines. Wellp… 

Mon, 04/20/2020 - 10:59

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Barkuti
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Dioda wrote:
… I have one "flat bottom" 4000mAh ordered few months ago. It has such diameter, that it does not fit any of the earlier Convoy 21700 lights. …

That must be a Lishen LS21700SA rewrap, same cell as reviewed by Henrik a couple years ago already. I know the cells reviewed were ringed bottoms, but I say this just because it is known they (Lishen 21700 cells) are slightly thicker, Henrik measured ∅21.7 mm.

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Dioda
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Yeah, my older 4000mAh has around 21,7mm. Do you know what is then the slimmer 4000 version and what could be the 5000mAh model?

Barkuti
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Had to come back and fix my cell lenght figures, somehow I wrote 71.4 and 71.6 mm Facepalm but no way.

No idea Dioda, suffice to say.

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Dioda
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So I finished the NOR test by Li-500 charger. Apart from the totally random, out of whack IR values (ram it in the charger till it shows satisfying values) both of these “thin” cells performed like this:

The 5000mAh clocked at 4442 mAh, with IR around 39
The 4000mAh “thin edition” ended at 4672mAh with IR 23

It is possible that they are actually the same cell under different wrapper, would not recommend them for any real high drain applications, due to their unknown specs.