First off, this thread should probably be in fixed lighting if you're talking about screw-in light bulbs. Second, the honest answer is not until they get efficiency up to around 250 lm/W. You're limited to about 3-4 watts heat dissipation with the light bulb form factor. Active cooling really isn't feasible due to cost/reliability constraints. Right now it's pretty much impossible to get over ~600 lumens unless you go with an oversized heat sink. The only way to increase output will be when LEDs put out more light than heat. Given that Cree recently broke 200 lm/W we may not have as long to wait as I thought. Maybe in 5 or 6 years you'll see screw-base LED bulbs putting out the same as a 150-200 watt incandescent.
Active cooling really isn't feasible due to cost/reliability constraints.
Besides, it's totally overkill for pretty much any current LED application. There isn't any need to cool an LED below ambient room temperature, so you might as well save yourself the time and design a better heatsink in the first place.
Yes, it can be done. You just need 8 XP-G running at 1.5 A each and if they're run in parallel, a battery that can give 12 A while maintaining a reasonable voltage. It would be easily pocketable. BUT you wouldn't need to worry about runtime of the battery because heat from all those LEDs would mean you wouldn't be able to maintain 3,500 lumens for more than a few seconds. :sigh: You didn't say you wanted lasting power.id love to have a 3500 lumen pocket torch IF it can be done :devil:
Second, the honest answer is not until they get efficiency up to around 250 lm/W.
And pray tell is there a problem with saying you know how to get a certain efficiency?You mean Cree actually putting 250lm/w emitters in production, or just issuing press releases saying they know how to do it? I'd say 80% of the people that frequent this forum don't know the rational difference (nor care)
In theory yes, in practice no, and the only way to do it in theory is to color mix red, green, and blue LEDs to make white. Phosphor whites have inherent Stokes losses which would make them about 82% efficient in the best-case scenario ( that's with a 100% efficient blue emitter ). You can tweak the emitted spectrum to increase lumens per watt ( at the expense of color rendering ), but you still come up against the ~82% limit. All that being said, I think eventually we'll see LEDs which produce 75% light, 25% heat, perhaps even >80% light, <20% heat. Right now the best bin XP-Gs are up to 40% light, 60% heat. The best production blue emitters are about 50% light, 50% heat.I wonder if it will ever be possible for a LED, or other semiconductor, to only output radiation in the light spectrum and not heat.
I wonder if it will ever be possible for a LED, or other semiconductor, to only output radiation in the light spectrum and not heat.