Test/review of Samsung INR21700-30T 3000mAh (Gray)

[CuriousOne]

China 26650's already hit 5800mAh @ 10A discharge.

 

[SubLGT]

"Mooch" has also tested this cell, from the perspective of vaping use.
https://www.e-cigarette-forum.com/f...lts-an-incredible-40a-3100mah-battery.798683/

This is a 21700 cell (21mm diameter x 70mm length) that is an incredible performer, running over 20% longer at 30A continuous than the Sanyo NCR20700A thanks to its incredibly low internal resistance of 10-12mOhms. This low internal resistance reduces voltage sag, letting the 30T run for longer before the voltage drops too far.

As is typical for a Samsung cell, I consider it to be underrated due to it running cooler than others at its factory rating. I am rating this Samsung 30T at 40A and 3100mAh. Its maximum vaping amps (MVA) rating is 60A, limited by temperature.

According to the data sheet, running this cell at 35A for 250 cycles will leave you with 60% capacity.

 

[Gauss163]

^^^ Do you know if Mooch is truly measuring DC internal resistance, since he reports about half the value that HKJ reports.

 

[SubLGT]

I have not seen Mooch's protocol for testing IR.

Here is his test equipment and setup:

https://www.e-cigarette-forum.com/forum/blog-entry/my-cell-testing-equipment-and-setup.7431/

 

[SubLGT]

Here is a interesting overview (written June 2017) of what is available in 20700 and 21700, from the perspective of an e-bike enthusiast.

https://www.electricbike.com/new-21700-cells/

 

[SubLGT]

Samsung has a new 21700 cell, the 40T. More capacity than the 30T, but less current capability.

Tested by Mooch:
https://www.e-cigarette-forum.com/t...3900mah-battery-better-than-ncr20700a.842165/

...This is a fantastic performing true 30A cell that easily beats the Sanyo NCR20700A at both high and low discharge current levels. At moderate power levels this Samsung 40T even beats the incredible Samsung 30T, hitting harder for almost the entire discharge down to 3.2V and for a lot longer too.
...This cell delivered 3962mAh and 3985mAh in my capacity tests….

 

[Overmind]

The 26650 size seems to be topped out at 5200mAh, with apparently no one working on improving capacity further. Samsung allegedly has a 5300mAh mid-power 21700-53G cell planned for future production, which could make the 26650 an oversized and obsolete form factor.

I have some liitokalas that reach 6000mAh in testing at 1A, they are labeled as 5100-5400 (various types).
Some 26650 makers seems like they focused on providing high current rather than high capacity. In theory, you could make 7000mAh normal current 26650s, but there's not much demand of them.