FTC needs to step in and do something about the L.E.D. type light producing devices that advertise certain output but can not remain at that output for more than a few minutes.
L.E.D. type flashlights are consistently full of technically impossible claims or lying by omission yet they're regularly getting away with it.
High-performance 2000 lumen flashlight with focus beam, OLED display, dual power, and TACKGRIP™ for rugged comfort. Built for serious reliability.
luxpro.com
which claims to provide 2,000 lm for under a minute (plausible...)
However, their claim of 1,200 lumens for 3.75 hrs or 4,500 lm-hr is a complete lie.
It has a 3.7v 2Ah battery or 7.4Wh. Even if the light got 200 lm/W (more or less gold standard in 2025) , the maximum would be 1,480lm-hr, constrained by battery energy content. So, the maximum it can deliver at 1,200 lumens is 1 hr 14 min; not 3hr 45 minutes. So, like their corded brethren, the output is dimmed down after a short period.
No further explanation is needed that getting 1,200 lumens for 3hrs and 45 minutes from a 7.4Wh battery is a lie.