Cree XP-L V6 2C led, tested against XM-L2 T6 3C, edit23/7: I repeated the test and measured a dedomed XP-L

I think they’re rather slightly less efficient at the current levels we’re interested in. (3-6A)

The XP-L does have a higher lumen output but at a higher Vf. That is a big obstacle when trying to direct drive these LED’s.

But the small die size is a clear advantage, I can’t wait for super throwers using this LED. (TN31 or TK61 + XP-L at 5-6A)

Thanks for the tests djozz!

Do they? As I read some unofficial information both XP-L and XM-L2 have the same die size (2mm x 2mm). Now who can help to confirm this? The data sheet found in CREE website doesn’t specify this.

Die size is the same as XM-L2. So it wont throw better than XM-L2.

This will be future reference data. Like Tom E said, we need to know if you tested V5 or V6. My first impression when looking at these numbers are that Im not impressed with the XP-L. I expected it to be better. If you tested V6, then Im certainly not impressed based on the graph.

There are pics in the other XP-L thread of a dedomed XP-L and a dedomed XM-L2 and they are clearly both using the same die. It is a XM-L2 die stuck onto a 3.5x3.5 XP-sized substrate.

Whoops, sorry about that.

So no significant improvements over XM-L2 technology. :~

oops, that was a bit of sloppyness on my side, sorry about that, it is very important to mention the right bin and I made a mistake: I looked up the order confirmation from illumn.com and it was indeed a V6 bin that I ordered. So that leaves you all even less impressed . I corrected the OP!

Thanks to you all for the appreciation of the tests. I have one of these emitters leftover, it was next to the tested one in the same piece of reel. Out of curiousity, one of these days I will do an exact as possible same test on that one (but up to 8 amps, I don't want to loose this one) to see how consistant the results will be. Of course if the results do not exactly match I will never know if it is a difference in the emitter or an inconsistancy in the testing, but undoubtedly it will give some insight in something .

I wouldn’t call it an improvement so much as a variation and we like variety. Now you can more easily use an XP-L die on a 10mm sink pad with more room for wires and optic. The drop off at high current is unsurprising given the smaller center pad. What is surprising is it’s ability to run even with the larger footprint XM-L2 as long as it does. That might be due to the size of the heat sink though. The next issue will be getting small optics that fit the larger dome. Even with XP or Nichias a 10-15mm optic doesn’t focus too well.

This may be pretty much what I can do as a hobbyist, but there are some very easy major improvements if I just put more money into it (that I will not do for the time being):

1)have a light source officially measured so you do not have to rely on averaging multiple wacky sources,

2)put in a better luxmeter, not so much because those tend to be calibrated (which is of no use anyway when applied in a sphere), but because the better optical filtering makes the wavelength response follow the standardised human eye wavelength response better,

3)put in a wavelength analysing device. Texaspyro put some rgb sensors in his sphere and can measure colour temperatures and other interesting things going on with colour balance, pretty cool, but what you really want is a spectrofotometer with a handy sensor that you can stick into the sphere and that can produce true wavelength spectrums, so you can do colour analysing from that .

4) (and that is something I could do sometime) add a temperature sensor somewhere close to the led (relic38 did that during his copper board comparisons) and see what is happening there despite of the maximum cooling that I tried to achieve.

This may be a big flop, but I really want to try to use 2 XP-L's in a TeePee or "V" formation. Hoping it will give a bigger hotspot than an XML, but more intense than and MT-G2 (and hopefully than xml too). The TeePee or "V" formation will help bring the 2 emitter's dies closer together. It well also aim the most intense portion of the emitted light at the reflector (which is were most throw comes from). The positive contact pad of one will be in contact of the negative contact of the other for a 2S electrical formation. Might be able to file off small bit of the substrate edge to bring them ever closer together.

It might also have a some what elliptical beam pattern, which is a bonus for me as we see wider horizontally than vertically.

Djozz,

It would be neat if you used your remaining emitter to do a dedome test.

Just cross posted with your Post 27 djozz. Those do indeed sound like sweet upgrades. Money and time constraints, they are a bummer, but do make us more creative.

Thanks for the test. These results are significant, at least if you agree that different bins are significant, which I do. Hopefully the price comes down and these continue to be remain available.

I'm going to try getting these into a lantern this week and go up from 125 lux with a XM-L2 T6 and stock Noctigon up to 500 lux with 3x XP-L V6 and a BLFDD driver. Unfortunately max output will quickly drop off because the battery and thermal mass is small, but it'll be fun for a few seconds.

Overall these #'s make sense to me. Even that you are seeing about 7% higher than Match's, it makes more sense to me, considering a 6.5A TN31 de-domed XM-L2 U2 1A seems to be about 1,700 lumens, making Match's #'s look a little low. I thought Match used a U2 1A though. We've been seeing close to 2,000 from domed XM-L2 U2 1A's at above 6A - I just always thought Match's #'s were a bit low, or me and a couple other guys are too high.

In my P60 tests (at 3.5A I believe), I saw the XP-L V6 do about the same as the XM-L2 U2 1A, which I think you would see as well, but the tint is nicer on the XP-L in this head to head.

Thanks for the comparison test djozz! Great work and very nice equipment!

Thanks a bunch, Fantastic Work!

I’ll be using mine on 3x noctigons.

Same. Too bad those quad XP boards were limited production or I'd be trying to talk Richard into carrying them when Carclo optics come out.

I got a few of those copper quad boards from member Dsche (with bonus: cool Russian stamps!), I would not be surprised if he still has some, you could try a PM, he seems a very nice guy.

I think he still has some too. I ordered a dozen. They've been sitting in New York for about a week. I'd like to order more, but it's going to have to wait a little while...I'm sure I'll come to regret waiting. Too much money spent recently for too many pending projects...

Thanks djozz. I have little to add to the conversation right now - all relevant points have been addressed. I just wanted to chime in to reinforce how much your testing is appreciated. I personally use your graphs a lot and often refer people to them. (& Congratulations on your success w/ the integrating sphere.)

Today I took some time to do some further testing on the XP-L.

I had bought two of the same leds (XP-L V6 2C, from Illumn.com), in one piece of cut reel, so they were right next to each other. The first one was destroyed in the crash test of the OP, and today I used the second one to repeat the test in order to find out to what extent the results are reproducable. Of course if the results from the two leds differ much I can not tell what part comes from variations in the method (i.e. it was 5degC warmer today than it was last time) and what part is variation in the led.

I used the exact same equipment, even the same star and led-wires from the first test, I just removed the faulty led and reflowed the other one. I tested the integrating sphere with one of my reference lights to be sure it read within 1% the same as it did last time (it did).

Here's the result, I plotted the results of the second led in the same graph as the first one, for comparison (I left out the XM-L2 3C results from the OP, just the two same spec'ed XP-L leds). I measured up to 8.5A this time to save the led for further use:

The second led measures slightly different from the first one: the voltage reads about 0.05V lower at most currents, with a maximum difference of about 0.1V, the output at most currents matches almost exactly the first led, only above 6A led#2 starts reading a bit lower than led#1. So this is not an efficiency difference (that would affect the entire curve, not just above 6A), but it looks like led#2 shows slightly worse heatsinking than led#1. Perhaps it is the led, perhaps it is the reflow that was not as perfect, I don't know: the difference is not so great that I feel an urge to find out.

What I am happy about is that this integrating sphere system seems to perform consistantly, I am really beginning to trust the thing :-)

While I was at it I thought it would be nice to compare this led domed versus dedomed. So after the test, before it was cooled down, I took the copper mount out of the sphere and with the led still hot I dedomed it by lifting the dome off from the side with a scalpel. It wasn't the cleanest dedome I have ever done (usually I do dedomes under a stereo microscope, I had to do with a loupe this time), but the die was clear from silicone afterwards, so the dedome was effective (the led is illuminated from the side to show remaining silicone well):

(stereo pic)

The dedomed led went straight back into the sphere for direct comparison with the domed state. I was very surprised to find this:

(sorry I'm not very good in making chart dimension the same everytime, they differ a bit from the first chart)

So what has happened? The concensus is that dedoming lowers the Vf (that is at least a suspicion) and costs at least 20% output (that is measured by many). This led however dedomes without light loss (that is: nothing under 5A, only slightly above that) and the Vf stays dead-on. Tell me what's going on here?, it looks like the performance is the same, just at very high current the heatsinking seems to have suffered somewhat, but I can explain that if I must by the better heat dissipation properties (surface area) of a dome vs direct air.

The led was really dedomed well (see pictures above), and I checked the light colour compared to a few other leds: xml2 3C, Nichia 219B, an xml 'cool white' led from the spare leds box (you can find out which is which :-) , the XP-L is on the right side in both pictures):

Pictures do not show tint well, but by eye the dedomed XP-L looks like a little under 5000K and more yellow than both the 3C and Nichia. So it definitely looks like the tint shift that you expect from a succesful dedome.

I can think of three theories, all quite unlikely:

1) the tint shift to a warmer tint leads to less output but at the same time the luxmeter is more sensitive to the warmer light, and those two effects level out. This is highly unlikely, the wacky wavelength response of this type of luxmeter can not account for a huge 20% measurement error for a mere 1000K tint-shift. And besides, the by many observed output-loss upon dedoming was very probably done by the same type (or the exact same) of luxmeter as is in my integrating sphere.

2) the slightly altered 'beam profile' of the dedomed led as compared to the domed state causes the 20% measurement error. This is not true, shining a focussed aspheric flashlight around in the sphere at all possible angles causes very little variation in the reading, maximum variation is 2%, only projecting the led image straight onto the baffle shows a reading 10% less.

3) this is the conspiracy theory : the XP-L's that Cree sells at the moment have domes that do not attach well to the die: domed leds behave like dedomed leds in light colour and output. It would explain why I do not find an efficiency for a V6 that is any better than a T6, it would also explain why Old Lumens notices such a warm tint for his XP-L in that HD2010. I failed to check the tints of my XP-L's beforehand, so I do not know about them. How's that for a theory :-D

There must be theory 4 that explains it all, like my measuring methods are flawed after all and such. Enlighten me :-)

One theory: The CREE data sheets are in fact correct and the XP-L V6 is truly brighter than an XM-L2 U2, but they did a crappy job on the dome because of the tight space on the XP footprint? Smile