Nice work Ouchy! I have been thinking about picking up a COURUI since I first saw it... There was no rush, and I was hoping for a sale or something, but maybe its about time..
Dale I guess everything is relative if you want it to be relative... I dont think its reduntant to consider battery size if someone have gone through the whole process of making a bright single cell light... Especially if a user have bought a light, new emitter, maybe special FET driver or well stacked 7135 driver, AR lens , maybe cooper pill and such, and then cheap out on battery format... The most important factor in order to maintain high output and get to it after basic mods are done..
Just to put some comparison graphs in this thread.
Panasonic 18650PF vs KK ICR 4200mAh (its PF cell inside Orbtronic 18650PD)
Samsung 20R vs Sony SE US26650VT..
The Keepower 3500mAh IMR you mentioned offer quite similar performance and more capacity compared to the Sony. For most people that would be the better cell.. The Sony cell is better suited at higher currents (More like 10A and higher).
7-10A is normal for our (single emitter single XM-L2) lights? Id like to see someone hit 7A at the emitter in a real flashlight with the best possible single 26650 or 18650 cell and an XM-L2. And preferably stay there for more than 2 seconds too...
The 20R and similar cells might give marginally better peak number when freshly charged, then voltage goes down like a rook compared to a good 26650 cell... This is why I say real world.. you seem to be very focused on the peak performance the first minute with a freshly charged cell.. In your book that would make the red graph from the 20R cell better. In my book the Sony 26650 cell spanks the 20R and probably every other 18650 cell when it comes to its ability to maintain voltage in real life use, not just a peak numbers test... I seriously doubt the latest 18650 have made much progress from the 20R...
I have bought my Sony 26650 cells from WB in the past, usually on sale...
I apologize in advance if any of my posts seems harsh or condensing in some way. As someone who is also interested in high output in many of my builds, I just find the extreme focus on the absolute peak numbers quite stupid at times, especially when they go at the expensive of other things that are actually noticeable.