Cree Z5 bin, over 2800 Lumens @ 3 amps

On the current path and speed of evolution we've already been seeing from Cree... We should be at a Z bin (!!!) in 4-5 years... with over 2800 lumens at 3 amps only using the power curve of the XM-L as the example.

Advances that accelerate the overall process, as well as the efficacy curve up into higher currents, are both likely to happen along the way. So the currently imaginary Z5 bin could happen in less than 4 years, and could be much better performing at higher current.

I just thought I would post this, even though it's only speculating so far, it's not a whole lot of speculation. This WILL happen.

The theoretical upper limit to LED output is somewhere around 400 lumens/watt so that is within theoretical limits. However as one gets close to physical limits, progress tends to get slower and slower.

This is true, and completely unscientifically taken into account, in that I tried to see what is happening as an S curve where we're at the highest acceleration rate of improvement right now. In other words we could get closer to that faster for the first 2 years (which IS in line with what Cree has been doing), slowing down in the last 2-3 years because of what you mentioned. But that would be more speculation than I would say "will" happen. Unexpected jumps forward and also unexpected limitations can (and probably will) alter the timeline.

I don't know that the LED's are getting brighter. Instead they are getting bigger and being driven at higher currents (more light overall for sure). With the XM-L, Cree started binning them at 700mA instead of 350mA. This trend doesn't work out that well for flashlights since the batteries aren't getting any better. The SST-90 gives off plenty of light, but you have to provide some serious battery power to get 9 amps.

The SST-90 might actually be beyond a Cree Z bin, at 1000 lumens for the Luminus WN bin, but that's a 9 sq. mm LED driven at 3.2A, vs. the XM-L being a 4 sq. mm LED driven at 700mA.

internal combustion engines are a prime example for this.

With passenger cars, horsepower peaked sometime around the late 1960's, the early 1980's saw some benefits in a slight power increase and lesser fuel consumption form roller lifter cams and electronically controlled fuel injection. Even super-future rotary valves, variable valve timing and gasoline direct-injection of today don't make that much of a difference compared to the leaps taken decades ago. The further something advances, the less impact the changes will have. Just look at exhaust gas NOX limits, the number of digits after the decimal point gets bigger and bigger.

Still, I think that as development of newer technologies progress, Luminous SST-90s (just an example) will become cheaper within the next few years. Just look at the Cree T6, around january they were almost twice as expensive as they are now. The four XR-E's I bought in late summer 2010 are much cheaper by now, already.

That's why I try not to rush in my purchases, especially when it comes to electronics.

Problem with that is, "By the time you can buy it, it is obsolete". Or you can hang on for ever waiting for the Next Great Thing. As far as I'm concerned, the XM-L is The Next Great Thing. Though XP-G devices are more suitable to extended use on batteries. 3A is a lot to ask of any cell - and an 18650 will give you well under an hour at that load. Myself, I'm not that bothered, the power here is very reliable (30 minutes of outages since 1990) but others don't have reliable power and depend on batteries for light - then runtime becomes a LOT more important.

Or for bike lights where you want it to be very bright, very light and run for hours. Pick any two.

I think Sixfink had a great analogy with the gas engine, and one I can relate to: The last engine I built was a 4.6l dohc for a mustang. Some of the folks I work with who grew up with the old muscle cars started asking me about dyno numbers. They didn't seem all that impressed with @620bhp out of these new-fangled fuel injection motors, saying they were able to beat that with a good 'ol carb/bigblock setup. I agreed with that, but then went on to explain that they never saw 26mpg highway or had daily driver reliability with those set-ups either...

After a certain point, it all comes down refinement. I think that's what I'm looking forward to most with these new emitters. Better color rendition, better emitter size/lumen ratio, and of course greater efficiency. We may never see a 400lm/watt emitter, but imagine one with the output of an xm-l that's the size of a xr-e and has a high CRI. Hmm....yum.

I just like saying that .. bigger isn't better ..want a big screen TV ?..Do what mom told you not to do .. get closer to the screen. the battery is the limiting factor .Match proved it's terrible easy to just add a few more xml's..He just never tells you that the supposedly innocent looking gas can is really a car battery .