From memory the minimum runtime listed is 10 hours on ultrabright which, honestly, is ridiculous. If you had a rider behind, he'd probably want to kill you if he could still see past the sunspots.
I'll check bumpf that came with it, and see if it checks out in use.
There's a review here of a pre-production unit that says 7.5 hours at full whack.
http://www.londoncyclist.co.uk/blaze-burner-rear-light-review/ Maybe they're right. I do know that the light is meant to drop back to standard brightness once the charge gets low and that is meant to give you 5 hours before the light goes out.
One thing that isn't great is they've removed the "bayonet" style fitting lugs so the light can rotate. It doesn't move a whole lot, but I wouldn't want to put it on a seatstay if it could reach the spokes.
Edit:
the instructions claim the following runtimes/mode
5H on Full Bright
60H normal steady
10H sweep
18H Beating
18H Chase
10H Sides
Just to show how bright this thing is on full power:
In this unscientific test I'd say that the burner is as bright as the fog lights of a Range Rover. The central light in the picture is the blaze burner resting on the rear bumper.
