I see someone else has discussed tests on the Rebel 100lm whites.
I have gotten some of these Rebels myself, but am having a difficult time believing their spec. My story's different enough that I don't want to threadjack him.
First a few notes. One breakthrough with the Rebels is that it tolerates up to 175C junction temp and is rated for full life at 135C. Second, if you can, solder it, this gives a very low thermal resistance with no danger of glue leaking onto the electrical contacts. I used like 1.5 sq in of PCB of unknown foil thickness and by watching the delta-V under constant current as it warmed up vs the spec sheet voltage-temp coefficient shows the die temp was still acceptable at 700mA.
Here's my problem. I have a Lamina BL2000 Red here, rated for 270 lumens(!!) at 2.1 amps mounted on an aluminum slug. I have 3x red-orange Rebel LXML-PH01-0050 rated for 100 lumens at 700mA mounted on about 4.5 sq in of PCB.
So the book says the Rebels should be slightly brighter. There is not a significant color difference that I see, but the Rebel is notable dimmer at all viewing angles when I drive these side-by-side. This is troubling because I know the eye generally views intensities as the square of the candela value falling on it so the lumen different is significant.
I have no equipment to measure this, but I can go back and change the drive current on the Lamina. I have a dual power supply and flicked them on at the same time so I can visually compare the apparent output in the initial moment before the dies heat up and begin reducing the light output. From what I can see, 3x of the 100lm Rebels @ 700mA each only compare to the 270lm BL2000 when the BL2000 is being driven at about 1 amp, approx 50% of the current where the BL2000 produces 270lm! So assuming flux is proportional to current in the BL2000 and the BL2000 is operating at spec, the Rebel is only putting out 45% of what it's supposed to. And this is 3 devices in series and they all appear similar in intensity, no single defective one or anything.
I checked to be sure the packaging said this is the red-orange 0050's. It does.
I kinda doubt the Lamina BL2000 I'm using as a reference is performing twice as well as its spec indicates. Both specify lumens at 25C pad temp and I think I handled the temp issue anyways by only comparing in the moment after it's turned on. By Rebel spec, the pad would have to be some 100C for its output to degrade this much!
What's up here? Why can't I get the expected output?
Anybody in Austin, Tx got the equipment to measure these?