A quick report of a Luxeon V2 5000K 70CRI led test, because it is late already. I got a bunch of these leds cheap from Arrow, the first experiences seem nice so here’s a test.
Test methods can be found in earlier led tests of mine, links can be found via my signature at the bottom of this post.
After the test (I kept the led at 10A for a minute) I found that performance had significantly gone down, also at the lower currents (like 30% worse compared to before) , and upon inspection it was clear why:
It is not clear to me when that happened, the curve of the V2 at least looks steeper than the other leds that I put in the graph. But can not tell if that this curve is typical for the V2, or that damage already started at 5A, or that my reflow was not optimal and this led would allow higher current with a perfect reflow. At least around 5A this V2 has better output (although at a bit higher voltage so efficiency will be close) than the XP-G3 S5 bin that I tested before. I would say if the curve is indeed typical that my sweetspot for this led is at 4A.
(btw the tested 219C that is in the graph was a very low output bin led, a new 70CRI 219C led would have better output)
(next to a XP-G2 to show that both die size and dome shape are close)
Reserved for some tint observations, perhaps some pics added later.
In summary: in a Convoy T2 light-OP-reflector flashlight at high, I get 290 lumen OTF (30% more than with the stock 4000K-tint XP-G2) , the hotspot is 4900K, 72CRI, slightly above the BBL so not the rosy appearance of the 4000K Luxeon V, but still a perfectly good tint without any green hue. The beam profile is very nice, no odd tints in the corona (unlike the new Cree leds) but just a fine beam as we are used already from the Luxeon V.
Edit: In the above chart the SST-20 is missing because I did not test a low CRI high output version. But here’s the chart of maukka’s test:
This SST-20 led tested has a bit less output than the Luxeon V2 of the above test, still when considering that maukka’s calibration is a bit lower than mine. The voltage at 5A is slightly (less than 0.1V) lower than the Luxeon V.
Wow, I was looking forward to this test but I must say the results make me sad, I can’t believe just how much sanding down the diameter of a carlco quad optic a few mm really costs… I may as well swap to a triple, probably for sure I’ll get more lumens otf at lower current.
My djozz-lumen most likely is between 7% and 10% high (depending on actual spectrum) compared to real lumens (I accept maukka’s calibration as closest to real), but I stick to my djozz-calibration for comparison reasons to older tests. That said, the djozz-calibration is way lower than what most flashlight manufacturers (including the high end ones) seem to use.
Thanks for the build report and the measurements. I also believe this OTF loss is on the higher end, but I don’t have anything to compare the result to.
I am planning on using the Carclo quad optic for the V2s that might come in tomorrow.
38% loss from a XP-type led in a Carclo optic sounds like something is wrong. I do not see that the Luxeon V2 is optically so different to account for that. A XP-G2 shows about 18-20% loss in a Carclo 10570.
These style LEDs that have the phosphor to the side of the die also emit significant light from the side-phosphor. The TIRs might not collect that light as well so that could explain the additional loss.
I do not buy these optic losses. There is likely some other variable at play.
I do not trust my sphere cause the napkin math doesn’t make sense but here’s what I get when I take apart my Emisar D4 w/ L1V2’s:
2,650 lux w/ optics + lens (143lm)
2,780 lux w/ optics no lens (150lm)
2,870 lux w/ no optics no lens (155lm)
I used the linear setting it defaults to when you reset the battery. Granted this is the 10621 optic both show like ~90% efficiency according to their respective datasheets.
What setup are you using to measure? I think your lumen reading with no optic maybe be getting direct light to sensor when measuring “OTF”. The beam angle is much wider after all so it can spill into something very near it.
Just a box with paper lined in it and Zak’s ceilingbounce app. That’s a good point. Unfortunately I don’t have a DMM at the moment to measure the current draw, but it’s got 20awg driver leads and bypass with a solid copper heatsink and with a fresh VTC6, at 5200 lumens seems to pretty much drive the emitters to the max.
That number is too high for a triple and I’ve had similar issues with my shoe box setup. Try adding a small white divider between your phone sensor and the light:
Even this is probably not enough but I suspect you will see lower numbers without optic and similar numbers with optic. If that’s the case you had too much light getting to the sensor without bouncing around.
Alright so, I just remeasured and did it with 2 phones as well as a divider between the phone and light. With one, I got 2700 with optics and lens, 3591 bare. On another, I got 2900 and 3790. So that’s a 23% and 24% loss. I think that seems right? This was done with a VTC6 at about 70% charge.
Lets say you are pulling 12Amps at 0s = 4200 djozzlumens * .80 estimated losses = 3360 djozzlumens at 0s, remove 7-10% for djozz bragging factor = 3024
I need to get a DMM. Anyway, I’m still happy with the Luxeon V2, although I don’t actually know what to do with it. I just saw Luxeon and 3535 and ordered because I haven’t actually seen one that is bad. The tint on this is absolutely gorgeous, very similar to the X-PL HI 3A, but less rosy.
If you decide the divider is more accurate I would re-calculate back to some of your old measurements for the “with optics” numbers so you have a more accurate “floody mule” number but similar numbers for everything else. If that makes sense. In reality it’s probably something inbetween but you may not want to try and redo a whole new baseline just for this.
Yea I’ll probably stick to this. I don’t have any light that uses otpics for now, sold all of them since I find them too floody. The lights with reflectors don’t have much difference in measurements with the divider so all is good.
