So, this is my first attempt to do something useful, if this could be the case.
I’m no expert, I’m no smart and I’ve not the knowledge or the equipment of HKJ, in case one of this facts does not appear obvious. Anyway…
I’ve bought some 25R from Fastech, some LG18650HE2 from aliexpres, and some NCR18650B (protected button top) always from aliexpress.
This are the test conditions
Just 1 cell used, HE2 had 1 charging cycle, 25R about 3, and NCR18650B are the oldest with someting like 5 cycles
I’ve not time to test more than one cells, at least not now…so that’s rough what I’ve to report within this scenario
Enviromental temperature from 16 to 18°C. I took me about the whole day, from 9.30Am to now 21.30 PM to do this, so there is an enviromental dT
All the cells fully charged at 1.0A
Cut V at 2.67V (I did it so low on purpose on IMR, and i was expecting the PCB to cut off on the Panasonic earlier but this did not append… maybe someone could enlighten me on this…)
Discharging current 4.0A
Test cunducted using magnets and a clamp
Hobby charger used Turnigy Reaktor 300W
internal resistance
25R 58 mOhms
HE2 42 mOhms
NCR18650B 128 mOhms
Here are the graphs
SAMSUNG 18650-25R
LG18650HE2
Panasonic Protected NCR18650B
Temperature over time (note that some fresh air could have touched the sensor while testing the Panasonic NCR186350B, you could anyway notice how the deltaT is, compared to the other IMRs)
Also notice how the 25R is cooler than HE2 even with a slightly more warm enviromental temperature
Voltage drop (sag) over Time
I’m open to suggest, how to conduct more objective within the limit of my actual piece of HW