kiriba-ru sent me these LED’s to test. I had never even heard of them before so I didn’t hold out a lot of hope for them but they really surprised me! They have one of the lowest apparent thermal resistance I have seen so far. This can be seen in how the output hardly jumps from a cold start, that says it is moving the heat away very efficiently.
The output is also very impressive at over 2200 lumens! This is more then any other 3V LED I have hot tested. The XP-L2 will make a bit more from a cold start.
The catch? It has a pretty high forward voltage compared to modern LED’s by Cree or nichia. Max amps you could expect in a single cell light would be around ~5-6A if I had to guess. That is still just under 2000 lumens though, so pretty respectable.
This also further confirms my hypothesis that the max amount of heat that the 3535 footprint can handle is around ~35-40W as all the 3535 LED’s I have tested have maxed out around there.
The dome started to burn around 5A but after scraping off the burnt area it completed the test just fine and a retest after it was over showed only a few lumen loss at 1A even after all that abuse.
I tried sticking an S2+ reflector over the LED and the beam looked pretty good, no tint shift.
Here are the results, click the pictures for larger versions.
Can’t find anything about this LED with a quick search. Could anyone share some pointers?
I absolutely LOVE the efficacy of this LED. Smells of really high sustained output.
How much can Q8 sustain? Because these with efficient boost driver would do 5500 lm with 55W including all losses.
The high Vf is a blessing for functional lights with our direct drivers, like the BLF-A6 or the Q8, those modern low Vf leds are driven far into the inefficient top of the output curve in direct drive, which is interesting for output addicts but it makes it a less useful flashlight. This could be competition for the XP-L, especially if it comes in good tints.
Btw, both the looks and performance are very close to the LG H35F0, I’d be surprised if these two korean leds are not very close related. Expect unbearable green-ness in the high CRI versions!
(I tested the LG H35F0 4000K 90 CRI led but did not post it, the led that I tested maxed out at 8.5A at a Vf of 4.09, with 1730lm output. Considering it was a 90CRI led, the 21% lower output compared to this Samsung led is perfectly consistent)
Edit: forgot my manners for a moment: thanks TA for another insightful test!
Nice test, TA. It looks like DigiKey has these at a pretty decent price and with good price breaks, too.
I’m wondering… would you be able to do a combination chart with this vs the XP-L V5 data you have? Looks like a real close competitor and a graph might help.
Also, what (if any) reflectors have you tried this in? How’s it look (especially with regards to tint-shift)? Maukka mentioned it looked good in his initial findings, then said it looked ugly when put in an EE X7.
Not necessarily, that is only for buck drivers with the same amount of input cell stages as in series output emitter stages. Besides all the theorizing, this for example is no problem with 2+S input for a single emitter, the down-side of this approach may be finding good 18350/26350/whatever short cells, formats which are not developed/manufactured by the big players in the li-ion industry.
This is the reason many times I've wished for a buck/boost driver which, on the other hand, would be necessary for driving violet/UV based emitters properly, I believe.
Stupid question here: are these led “good” to be used with the MTN DD drivers in triples or quads?
Since I started using the Wuben TO50R with these Leds, much has changed in my perception of neutral white and high CRI, so I wanted to build another light with these. But I want it to be triple or quad, floody!
That said, if you’re pleased with how they look in the TO50R optic and you can find a suitable optic for your build, I doubt you’d have any issue with a triple/quad and a FET driver. Between these having a higher vF and you running multiple (presumably in parallel), I don’t foresee any problems.