sma in the German TLF forum has tested the Luminus CFT-90, the new high-power LED from Luminus. This LED has a 9mm^2 Die, no dome and is rated for up to 27A. It’s factory mounted on a large copper pcb. sma tested it up to 45A (I had guessed beforehand that it goes up to at least 40A). See here.
As I predicted it has a suprisingly high luminance for such a large die. It managed up to 230cd/mm^2 which is better than any XP-G2 and almost as high as the Osram Black Flat at maximum current, but with 9-times the die size! At 40A, 4.86V, 194W it produced 5700 Lumens. Of course a XHP-70.2 can be much brighter, but it also has a much larger die and thus a lower luminance. There is also the fact that this Luminus LED is actually designed for continuous high-power use. The XHP-70.2 and XHP-50.2 and only designed for a maximum of around 30W and 15W.
Using this LED in a “flashlight” is of course very costly and requires a lot of effort. The LED already costs 100$+. A 20-40A Buck driver is also hard to get (I only found one for 90$). It will also be rather large. Keeping the LED cool is of course the most difficult part though. Active cooling is probably a must if one wants to run it continously at maximum power.
Every LED is inefficient when driven with a high power density. The XHP70.2 is no exception there. The Luminus LED has much higher luminance and thus will get you more throw. It will produce an amazing beam, that most here are not used to.
When comparing them one needs to take into account that the XHP70.2 will be dimmer after de-doming. So the difference in luminance is larger. The XHP70.2 has been tested up to 145W, so I will compare both LEDs at this power.
CFT-90 - 38A - 3.81V - 5600lm @ ??°C without dome - 228cd/mm^2 - 39lm/W
I don't know what temperature the LED had in sma's test though. The real values might be a bit different.
So the CFT-90 has a roughly 50% higher luminance compared to the XHP70.2 at 145W. Thats a noticeable difference! Both have a very low efficiency at such high power levels. The difference between the two is rather small in this regard. Luminus has definitely caught up! When considering power density the CFT-90 is actually much better compared to the Cree LED.
The temperature is also important. The XHP70.2 has a thermal resistance of 0.9°C/W without the PCB and the CFT-90 has 0.45°C/W with the PCB. So in reality the value of the XHP70.2 will be a bit higher. Both have a maximum allowed junction temperature of 150°C. Lets say the heatsink (flashlight) has a temperature of 50°C @ 145W (maximum temp that is pain free). Here's a rough calculation (ignoring the LED-heatsink interface etc.):
CFT-90: (145W * 0.45°C/W) + 50°C = 115°C
XHP70.2: (145W * 0.9°C/W) + 50°C = 180°C
So with this heatsink the XHP70.2 would have a high chance of failure and the Luminus LED would have no problem even though it has a much higher intensity and is less efficient. That's a large advantage if you ask me.
At this power level the heatsink of the XHP70.2 needs to stay cooler than 20°C (to stay under 150°C). You would need powerful active cooling to achieve this. The heatsink of the Luminus LED on the other hand only needs to stay under 85°C. That will be difficult but doable.
It’s much more expensive compared to the SST-90. >100$, but I find this genereally reasonable. It is designed to replace Xenon short-arc lamps. In the long run it is much cheaper compared to them because they have a rather short lifetime and require more power. It is also by far the most powerful officially rated LED on the market.
Interesting. Burn 27A worth of power to get what the 70.2 can do with 8A or so. I have a 70.2 in my Convoy L6 making 9200 lumens off of 2 26650 cells, commonly available driver and the emitter is less than $20. Not really seeing the appeal of the luminus.
I’ve liked the CBT-140 for a while, but it, like other Luminus emitters, is so inefficient it’s hardly worth the triple digit price point.
Edit: Not to mention that the extremely common and cheap XM-L2 is capable of a mile in throw (actually a measured 815Kcd) from a reflectored light. At only 4.6A. From a single cell. Simple FET driver.
The XHP70.2 P2 does not produce 5000 lumens at 8A when de-domed, maybe 4000. The Luminus LED will produce much more throw. More than the XHP70.2. More than any XM-L2 de-domed. It beats them all. In addition to this it produces a lot of lumens. The XM-L2 will do up to around 1700 lumens when de-domed. That’s quite a bit less. So compared to a de-domed XM-L2 you will get a hotspot that is 2.5x as large and at the same time probably around 30-45% more Candela.
The CBT-140 is basically the 5-years old predecessor. The CFT-90 is new, much more efficient and has a much higher luminance.
The appeal is this: it’s the best. The best always costs a premium. If you want over 100W of power in a single power-LED continously and not worry about the reliability, this LED is the only option (because of the lower temperature, see my post above).
I wouldn’t compare the numbers at the peak output. The inefficiency is indeed terrible. But at around 30A it’s much better in this regard (which doesn’t make it good actually). And it will still out-throw nearly anything on the market. And certainly anything close to its output.
I don’t see the point comparing it to XHP70.2. It’s much more powerful and efficient, but much bigger. XHP50.2 is much closer, actually pretty much the same size. And max output is close too, 5000 lumens with the dome. 50.2 leaks light to the sides, so it’s much less throwy with the same output. Efficiency? ~80W@5000 lm for XHP50.2 (with dome) and ~110W for CFT-90. Dedome and you’ll arrive somewhere in the 4000-4500 lm range with the same 80W consumption. Scale CFT-90 down to this level, it takes ~70W@4500 lm and ~60W@4000 lm.
Oh, don’t get me wrong… I’m not saying I wouldn’t like to try it out and see, but at the price point, the offset COB design, and the extremely high amp requirements, I don’t see myself doing anything with this one for quite a while.
When you want max throw, you can throw efficiency out the window.
The point is to get the highest possible numbers, and this is currently #3 on the list of highest intensity LEDs.
What’s so cool about it is that it can do this while also outputting a huge amount of lumens, which the first two don’t do.
Perfect LED for applications such as moving heads, which are starting to transition to LED:
And sky beams which are currently all short-arc:
Neither of these are “flashlights” and neither of them are “budget” so the majority of people on this forum won’t really get excited by this LED
I indeed did not take the domelessness (is this a word? O:) ) of the CFT-90 into account in my calculation, that makes a big difference.
If any host is suitable for this led it must be the BLF-GT, in fact its bulkiness and that it takes 8x 18650 batteries makes it more tailormade for the CFT-90 than for the XHP35, as if the GT temporarily is fitted with a XHP35 but in reality was waiting for this led .