Top 21700 cells: LG M50 5000mAh vs Samsung 48G 4800mAh

[thunderheart]

Hi guys! I've tested two high capacity 21700 cells - LG M50 (5000mAh) and Samsung 48G (4800mAh). The latter i had already tested before and the re-testing of another cell showed almost no difference with previous test results. The M50 is a new cell which is being sold as 10A one, but in its datasheet the maximum discharge current is mentioned as 7.28A. Nevertheless i've also discharged it at 10A to look at it's behavior.

The cells i've bought from Queen Battery.

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.

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 its datasheet to charge end voltage (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 about 25°C.

LG INR21700 M50 (Grade B)

This cell has absolutely no marking.

The main specs from its datasheet:
Nominal energy: 18.20Wh
Minimum energy: 17.60Wh
Minimum capacity: 4850mAh
Nominal voltage: 3.63V
Standard charge current: 1.455A
Max. charge current: 3.395A
Charge end voltage: 4.2V
Charge cut-off current: 50mA
Max. discharge current: 7.275A
Discharge cut-off voltage: 2.5V
Weight (w/o washer): 68±1g

The measured weight is 69.16g.

Test results:

Great results - 5104mAh/18.44Wh at 0.2C (0.97A) and almost 5000mAh at 5A! Even at 10A, which is way above the declared maximum (7.28A), the M50's curve looks very nice. I think it's a very capable cell and LG shouldn't limit the discharge current by 7,28A.

Samsung INR21700-48G

This guy is marked as INR21700-48G SAMSUNG SDI M5-1.

The main specs from its datasheet:
Typical energy: 17.4Wh
Minimum energy: 17.04Wh
Typical capacity: 4800mAh
Minimum capacity: 4700mAh
Nominal voltage: 3.6V
Standard charge current: 1.44A
Max. charge current: 4.8A
Charge end voltage: 4.2V
Charge cut-off current: 96mA
Max. discharge current: 9.6A
Discharge cut-off voltage: 2.5V
Max weight: 69g

The measured weight is 67.58g.

Test results:

At 0.2C (0.96A) the results are a bit higher than declared. At 5A and 9.6A the 48G showed good results with nice curves.

COMPARISON

At 0.2C.

Despite the 0.01A difference in discharge current LG M50 showed better result than the 48G. Pay attention to their curves - they are almost the same during the first half and they look very similar during the second half of discharging. This is because they use the same (or almost the same) chemistry.

At 5A.

The results are very close, thought the M50 is better again.

At 10A/9.6A.

I've discharged the M50 at 10A and the 48G at its maximum allowed 9.6A. Nevertheless the M50 showed higher capacity and almost the same energy in comparison with 48G.

CONCLUSION

Both cells are surprising with their results, but i liked the M50 a bit more than the 48G. I don't understand why did LG limit the max discharge at 7.28A, because it handles 10A easily. Of course the cycle life won't be the same as at 7.28A, but nobody expects a great cycle life at max rates. There is also LG M50 Grade A cell, which was unavailable when i was making the order. Does anybody have any official info about the difference between Grade A and Grade B M50s?

I hope this test was interesting to read/watch and i'll be happy if it was useful for someone Here is the video version of this review with size comparison between 18650, 21700 and 26650 cells:
[youtube]KGJDogOG4zw[/youtube]

P.S. this is my YouTube channel: www.youtube.com/thunderheartreviews It will be highly appreciated if you subscribe!

 

[Pajda]

Thx for this review, I finally got the M50 cells (also B Grade cells from QB) 14 days ago and I got similar results in nominal capacity test. Maybe the B grade is only marking for mechanical scratches on the case. But it will be fine when someone ask QB what is the difference. :wink:

I also started with cycle life tests to compare M50 with 48G and with 18650 cells. Both 21700 cells seems to have problem with 0.5C charge rate. I expected this problem with Samsung 48G, because 35E suffers with the same problem. But LG M50 shows similar bad result with 0.5C charge rate as 48G, where LG MJ1 does not have this problem and its cycle life is not affected with this rate.

 

[thunderheart]

Hi Pajda! Will you publish the results of your tests? I'm lookin' forward to it!

LG M50 shows similar bad result with 0.5C charge rate as 48G, where LG MJ1 does not have this problem and its cycle life is not affected with this rate.

Maybe the problem is in the form-factor? 21700 is bigger than 18650 and maybe there is a problem with overheating?

 

[AEM]

These results are really pretty interesting, but do you also plan to test the Panasonic NCR21700A and Sony US21700VXX that Queenbattery is supposedly selling? Though based on the pages of the cell only the Panasonic is really available. The Panasonic ones should be the closest in chemistry to the model 3 cells, and might have better cycle and power capabilities than the M50.

 

[Rube]

Thank you for sharing the test results. Logging cell temperature or even just peak temperature would be a very interesting, particularly at the higher discharge rates.

 

[Pajda]

Maybe the problem is in the form-factor? 21700 is bigger than 18650 and maybe there is a problem with overheating?

I do not think that bigger form-factor is major problem. My opinion is that this behavior is connected with the main goal of 21700 format which is another significant cost reduction. And there are two approaches how to achieve that. First, already well known approach, is that with bigger format we got less welds and less cells to manipulate. But the second approach was to use cheaper chemistry (NCA with significantly less cobalt or NMC 811 with less manganese and cobalt). And use of this cheaper chemistry in my eyes makes the problem with 21700 cycle life.

So using 0.5C charge rate (my standard 0.5C-1C cycle life test) with this two 21700 is above the datasheet recomendation. Both cells have nominal charging rate of 0.3C.

 

[Pajda]

These results are really pretty interesting, but do you also plan to test the Panasonic NCR21700A and Sony US21700VXX that Queenbattery is supposedly selling? Though based on the pages of the cell only the Panasonic is really available. The Panasonic ones should be the closest in chemistry to the model 3 cells, and might have better cycle and power capabilities than the M50.

Maybe Thunderheart has better informations, but what I know Panasonic and Sony 21700 cells are still unavailable at QB. Also Samsung have its own 5000 mAh competitor INR21700-50G(E). So we'd like to run tests, but we do not have access to the cell samples.

 

[AEM]

These results are really pretty interesting, but do you also plan to test the Panasonic NCR21700A and Sony US21700VXX that Queenbattery is supposedly selling? Though based on the pages of the cell only the Panasonic is really available. The Panasonic ones should be the closest in chemistry to the model 3 cells, and might have better cycle and power capabilities than the M50.

Maybe Thunderheart has better informations, but what I know Panasonic and Sony 21700 cells are still unavailable at QB. Also Samsung have its own 5000 mAh competitor INR21700-50G(E). So we'd like to run tests, but we do not have access to the cell samples.

Well I did say supposedly I’m not sure if it’s just some kind of placeholder page for when they do become available. I’ve put the link here

http://queenbattery.com.cn/252-ncr21700a-5000mah

And it does say it comes from South Korea so most likely it is just a mistake on their part, but I can’t be sure.

 

[thunderheart]

do you also plan to test the Panasonic NCR21700A and Sony US21700VXX that Queenbattery is supposedly selling?

Yes i do. I'll test them as soon as i get them.

Logging cell temperature or even just peak temperature would be a very interesting, particularly at the higher discharge rates.

I totally agree but unfortunately i have no temperature logger I have a quite accurate digital thermometer which i use to control the air temperature but it has no logging capability.

Right now i'm testing Samsung INR21700-30T (35A) at discharge rates up to 20A (it's my battery tester's limit). If nothing goes wrong i'll publish it in a day or two. The other 21700 cells i need to order first...