Update
after living in the right front pocket of my jeans with keys, coins, and money clip.
One day I pulled the light out and it would not turn on
battery was at 2.65 volts
this tells me the Folomov had been turning itself on in my pocket, the driver wont work below 2.7v. I did a test and at that level High mode is less than 6 lumens. So plenty obvious the battery needs charging.
I already hated the UI, and I did not love the inaccurate lumen specs, but I put up with those issues because I like the LED and mostly use low modes. The realization that it drained itself in my pocket was a sad awakening.
otoh, this light wont leave you suddenly in the dark… since it wont trigger LVP, which I hear from maukka is at 2.5v