LED runtime question amongst different co's

I did some searching but not finding what I am looking for. Surefire has the runtime of 12 hours for example for the P60L (I realize this is useful runtime and not the full 80 lumens etc). How does this compare to one of the Cree drop-ins for example from DX etc. Is there special circuitry in Surefires modules that the others do not have? I am looking at some of the Q5 or the module at http://www.dealextreme.com/details.dx/sku.6090. Would I get many hours of USEFUL light out of this or would this last for 1-2 hours and then just die out completely etc. I guess this is where regulated vs un-regulared comes in? I'm still learning..thanks for your input.

Like you say, it depends completely on the manufacturer. The good part is, we CPFers are getting very good at making runtime graphs of various lights. I have no experience with the DX dropin you describe, but I'm sure someone does. Perhaps you could request a runtime review?

Thanks, I guess where I get confused is that I read about the big benefits of LED of incandesent is the longer battery life but it seems may of the runtimes I am seeing with LED are still around an hour or so..some little more..others little less. My incandesents are rated at 60 minutes and 85 minutes..and my G2L at 12 hours but see other LEDS that only last an hour. I will research more about regulated vs unregulated as it sounds like that is a big part of the runtime equation.

It all depends how bright the light is. A current generation LED that runs for 90 minutes will probably push 200+ lumen from an 18650, which is more than an incandescent that will run for 90 minutes on the same battery or 2 CR123A cells. Conversely, you can get a LED light that will run for days on lower settings.

One thing is certain. You definitely get more lumens per watt with LEDs than with an incandescent flashlight. Whether you get lower lumens for a long time, or higher lumens for a shorter time is up to the maker of the light (or what level you run a multi level light on).

Thanks, it's all becoming more clearer now.. in the end LED looks like the way to go.. I like all of my lights..I like the warmness of my Xenon's but also like the look of the LED.. I guess each has it's place.

The best LEDs are about 100 lumen/watt. The best incandescent lights (that I know of) are in the upper 30's in terms of lumen/watt.

So, if you have a 8W/hr battery (typical Li-Ion 18650) you can run the LED at ~100 lumens for ~8 hours. You could run an incan at ~35 lumen for ~8 hours. Alternatively, you could run the LED at ~35 lumen for ~24 hours, or run the Incan at 100 lumens for 2.66 hours.