Tested the light with a 6.0ah FlexVOLT battery, fully charged each test.
On high, the light stayed on for almost exactly 3 hours.
On medium, the light stayed on for almost exactly 12 hours.
On low, the light stayed on for almost exactly 23 hours.
I'm repeating 'exactly' because each one was within about 5 minutes of those times....almost like it was programmed to do that.
The light is advertised as 2000 lumens on high. I can't seem to find what the output is on medium or low, but would be curious to know what it is.
Anyway, pretty impressive numbers.