15 minutes checked at 5 minute intervals. All taken at the pill.
SK98 5min= 96F 10min=105F 15min=112F
SK68 5min= 91F 10min= 99F 15min=106F
C8 5min=88F 10min=89F 15min=92F This light has heat sensitive circuits to lower light level as it heats. So it was dimming through the entire test and was a lower light level than the sk68 at the end of 15 minutes. Rebounded after a 5 minute cool off.
Battery temps after 15 minutes. SK98 =101F SK68=99F C8=90
Temps below pill half way between tail cap and pill. SK98=99F SK68=98F C8=88F all after 15 minutes on highest setting.
Rebound, 5 minutes after turning off. SK98=88F SK68=85F C8=85F
A lot can be debated and or said for these results.
Battery temp was much lower than any part of either the 68 or 98 host which means the aluminum was doing It's job and allowing the heat to escape through the body away from the cell and emitter.
Very often it is thought that the outside heating is a bad thing when it is most often a good thing. The heat is escaping as it is designed to and with no special circuits. The SK98 was still easily at 1000+ lumens throughout entire 15 minutes, same with the SK68 light level had not changed at all. I still need to complete the math on the highest output from the 68 with the emitter I have in it but it is easily 400 to 500 lumens.
The C8 did stay a good deal cooler than the 98 or 68 but at a major loss of light output. I did not meter it but it looked to be about half the original output. (a guess not fact but was visibly lower).
Would I take my 68 or 98 out into the woods or into a tactile situation. Without a doubt I would if for no other reason than I can go to full 100% for 15 to 20 minutes with no worry of failure with a blasting light. I can always back the level down to medium or low and right back to high and still get full light level.
The C8 I am growing to love,it is just a great little light. With that said I could not do the same with it. It would still be bright but not close to 100%, even if lowering the level the going back to high. I would still take it with me as it will outlast the others by an hour or more because of the temp sensitive circuits.
Thanks for asking, I have been needing to do that for several weeks now. On these I would not change anything, they are blistering bright. But moving forward I will be looking deeper into shedding the heat faster.