Luminus CFT-90 Testing - The Mother of all LEDs

High thermal mass doesn’t necessarily mean high thermal dissipation, if this LED was driven anywhere near its max in a GT it would overheat instantly.
I wouldn’t recommend it for any ‘normal’ flashlight form factor, more for something with AT LEAST a fan cooled heatsink, or preferably liquid cooling.

Mind that a well-fixed Q8 runs at over 20A already, at a comparable voltage, so half the current of the CFT-90 at maximum output, and does that for 3 minutes without getting worryingly hot. With its larger mass and surface area the GT should be able to run the CFT-90 at over 40 A for three minutes too before stepping down.

First of all, the heat from a Q8 is spread out over 4 points, the CFT90 is a single LED so the junction temperature will be 8x higher than a Q8 (since it will be producing 2x the heat output).
For this reason you would need to use a large copper base heatsink, or a TEC.

Second, the surface area of the GT is probably close to 10% that of the heatsink used in SMA’s test. Heatsinks have tens or hundreds of times more surface area than a flashlight like the GT with its few shallow fins.

Third, the mass doesn’t matter at all for heat dissipation, it’s just an energy reservoir.
If all you care about is a few seconds of high output then sure, the GT will work, but for practical purpouses and actually using the light for more than a few minutes on max it needs to have much higher thermal dissipation.

Personally I think any light that can’t maintain its max output for long periods of time is basically useless, it may as well not have that max setting.
Which is why I hate lights that are direct drive.

^ It is an ongoing discussion on BLF how desirable high output/fast stepdown flashlights are. For maintaining the high output of the CFT-90 for longer time the GT will not suffice, but I’m sure someone will do the mod :smiley: and I’m curious what runtime on max it will have :slight_smile:

Ah come on if those 25K+ lumen lights offer enough fun for a few second to such extend people buy it, sure seeing this monster led in the GT should be awesome :smiley:

+1 hope the price comes down and efficiency go up…

Might as well just make a flashlight with a flash bulb so you get those 100k lumens for 1/10th of a second…
People buy dumb things just because of marketing, such as 25k lumens for 30 seconds.

this is not true, the CFT90 has 0.45K/W to the heat sink, while a XPL has 2.2K/W to solder pad
the MCPCB mount adds a bit to that so probably 2.5K/W

so at 20A the CFT90 die stays cooler


If a light can not sustain MAX output for at least a few minutes it is USELESS to me. I categorize it as a WOW light which is impractical for normal use at that level.

A lot of people buy these modded lights from V54 and others just for that[The WOW factor]. These people do not even use the lights that much! Within weeks or a few months a lot of them are up for sale!

To each his own.

Those lights are useless to CAPO and I on the trail. The longer a light can sustain MAX,the better. That is my preference.

I know several people who probably have a 10K plus collection primarily for that WOW factor and not for every day use. They are entitled to their preference also although I do not understand it.

Turbo mode on my D4 steps down after 10 seconds.
Unless I turn it off before that, which happens half of the time. And I do because I use it to take a glimpse of a place that’s dark with the mode that I use at the time.
So yes, this turbo is actually useful for some people.

Despite not being able to cool this monster led on max, the GT still seems the best flashlight to try it in, just image what beam at not max amps will give :smiley:

Basically the same as the XHP35 HI since the die size is very similar, just a bit brighter from a few more lumens.

We are all different. I returned my D1vn after using it once on the trail. It got so hot, so quickly[to be expected but still disappointing].

I was able to set the driver and get it to run for 1:30 on turbo. By that point it was so hot you could not even run the light on 50%. I had to let it cool for a few minutes. These small lights are so powerful that there is no way for the heat sinking to dissipate all that heat.

For me a 10 sec. or 20 second burst is useless. That is just me and probably some others. I will admit I love Max output. My K40vn,TK61vn,M2Xvn and some others ALL can run at least 20 minutes on max b/4 they get too hot. The M2Xvn NEVER gets hot and can stay on max continuously until I put a fresh battery in. Then again, this light is only 1200 lumens and a much bigger light compared to the D1vn!

So the lesson I have learned is that these SMALL/POWERFUL[Even bigger lights that get too hot too quickly] lights have know practical use for me on the trail.

My smallest light for the trail is my TX25C2vn DD/Single mode XPG2. The rest are mid ranged and large torches.

I thought about this not too long ago, talked to others etc. It’s probably doable! 40A is unrealistic though if one wants constant light output until the batteries are empty, the light will simply get too hot.
I decided to try a de-domed XHP50.2 K2 @ 12V & 4.5A instead. This way I can use the stock driver with the nice U.I. and full regulation.

I actually found a suitable buck driver for the Luminus LED from some unknown Chinese company, but even this is rather expensive at 90$. I linked to it here in a thread over in the German tlf forum where I have been debating the usage of the CBT-140 for four years now. I actually thought about using the high-cri variant of that LED. Now THAT thing is really inefficient, similar to a halogen bulb.

Wow, If only I was rich, big fan of Luminus leds here :GLASSES:

BTW this isn’t a typical flashlight driver, it runs from wall AC power, but it will be perfect for this LED:\_–1
40A max and adjustable voltage between 3.6 and 4.4v
Very affordable too.

Here’s a 50A version too:

You sure about that?
It seems like a standard constant voltage power supply. This poses the risk of thermal runaway when driving LEDs. Doing this with a 100$+ LED seems a bit risky to me. :slight_smile:

Well, I haven’t found one that is constant voltage though…
As long as you have stable temps and good voltage regulation it shouldn’t have thermal runaway.
Pretty sure it will also artificially limit itself to 40A or 50A depending on which model you use, so in a sense it is kinda constant current.

EDIT- yeah it has constant current limiting, so if you want it to be 40A max, you can get the 40A model and just crank the voltage and it will limit itself.
With better cooling than in SMA’s test you can probably still get an increase up to 50A instead of 45.

I’m with Dale. (DB Custom) Love the MT-G2 because the tint always seems to be great (no tint lottery), And if you need more light just add more emitters.

I know I not with the majority but I’m still waiting for lower cost not 5lbs flashlight that can run 4,000 Lumens for 30 minuets. Not 30sec step down but an actual min 4,000 for 30 minutes min (now to me that is a bright useful light) same test but 3,000 lumens would be pretty dam useful also.

So tired of telling the industry that what matters is a big number on the box. Waiting for the day when the market will send a more sophisticated message to manufactures.

End soap box

Wish we had a 1 hour ANSI test we could get on the boxes instead of 1 foot or 1 meter.

You can’t break the laws of physics. The flashlight would really need to be 5lbs to disipate the heat.

A stock L6 can do 3500 lumen constant, but output drops as the batteries run down. Even that big light still gets scorching hot.

Maybe you want a single 26650 sized light with active fan cooling built in? That might do a constant 3k lumen.

You just have to keep physics in mind. All that heat has to go somewhere.