Just for fun, I put the thermocouple sensor from the prototype of my battery/led/driver analyzer (Any interest in a LED/Battery analyzer device?) on the head of one of these flashlights (with a fresh cheap ass bulk packed alkaline AAA) and switched it on high.
After 50 minutes the temperature reached 116 degrees F (started at 76F). Then the temperature curve rapidly bumped up to 126F over the next 8 minutes as the driver had to work extra hard to extract the last bit of full-power juice from the battery. Finally the curve started falling again as the driver could no longer fully power the LED. After two hours the thing is back to room temp and the light momentarily, randomly, flashes the LED as it manages to squeeze short burps of electrons out of the dead AAA cell (measures 0.60V)
It looks like you can expect a full hour of coppery high beam goodness out of a cheap AAA.
These things are really nice. I’ve been carrying it my pocket with my keys for over a week. I’ve walked over 50 miles that way. It’s not quite the uber-buffed, shiny tart that it started out as, but she still looks rather sweet. Unless you had a virgin to compare it too, you probably would not notice.