I got some 18650 from Tmart.com to test them.
I got
- 2 unprotected, flat top 18650, rated 2200mAh
- 2 protected, button top 18650, rated 2200mAh
The unprotected measure 66 mm in lenght
The protected measure 70 mm in lenght
I have tested both with my SKYRC MC3000 at 2A discharge until 2.8 volts are reached.
These are the results:
In the button top plot there is only one cell because the other one was dead on arrival (I measured 0 volts with my tester, tried to reset the PCB as I do with all my other batteries without any success).
The measured capacity meets the rating for the 2 flat top cells, while it exceeds the rating for the button top cells.