excellent info! much appreciated. edited first post to include 3v shutoff for both lights
I looked but did not see a review of yours posted, and have not noticed the 2.8v in the manual. Good to know yours shut off neasr that level, I understand what you mean, that there is rebound when resting, to about 3v. That is an excellent safe cutoff.
I had wondered, but have not tested, whether the Folomov would trigger overdischarge protection in the battery, if asked to produce maximum lumens. However, I dont know if the cell is actually protected, nor whether it is IMR.
from your comment I infer that the Folomov circuit simply will not light up below 3v, resting, since it rebounded, it tells me there was no overdischarge protection triggered in the battery itself… could it also be IMR… dont know, but can wish 
In any case, great to know the light turns itself off at a safe minimum voltage. Fun little light! I like how easy it is to hold in my mouth, or tucked under my beret, no clip needed for brief hatlamp use.