I just killed a battery to the point of being too low to fire. Then to make sure it was 100% too low, I pulled it out, let it sit for a few minutes, put it back in, and fired it a few more times. I did that about 3 times. The dead battery reads 3.083V. It has been sitting for about 10 minutes and is back up to 3.109V.
While I have my fluke meter out and am swapping batteries in my provari, I figured I would test the fully charged battery. I charged it yesterday, left it sitting on my desk over night, and have been carrying it in my pocket for about 5 hours today. It is one of the 18490's that came with my provari and it currently reads 4.185V