The A6 is a FET driver, right? Lexel said using a FET driver is not really an option for such an expensive emitter.
I assume he means it would be very likely you could burn it up. How would you like a $5 driver to burn up a $150 emitter? That would suck.
I’m sure you could ask him for more details. Here is his CFT-90 driver thread. Well, not a driver build thread, but the closest I could find.
The driver design is a buck.
How could you kill an emitter that withstands 40A? Heat I guess?
I guess he meant that it’s wasteful to drive such expensive emitter without precise current control. If you spend this much, it’s worth to spend some extra and really get the best of it.
Though in this case that “some” is actually large.
Non of my Lambda lights used anything like Lexel’s driver. Most of those that used the Luminous 90s were $70-90 emitters. Never had any burn up. But they best they could manage was 13-16A though and that is running on 4c or 4d cells. So I just wonder if it’s difficult just to get up to 40A without getting to the point where you get way beyond that.
You can use a fet driver , but due to the high Vf it can “only” draw up to 18-20 amps .
High Vf? 3.47V at 20A is high?
Divide it between 4 strong batteries and they’ll keep 4.15V.
This leaves us with 35 mOhm resistance in everything between LED and battery, I’ve seen report of resistances as low as 10 mOhm.
I’d expect 30A to be easy for our masters (15 mOhm).
With 8 batteries and 10 mOhm host there would be over 35A.
But Vinh reported getting just 20A. So something doesn’t add up.
I wish i knew what’s the truth ! would like to test a cft-90 but 100€ isn’t that cheap 
Just like any other emitter, too much voltage will either kill the emitter or your batteries due to exponential current increase.
Aren’t they any manufacturer papers of this led?Have you made any search about it?
I see “high current operation: up to 27 A DC”.So,how it could go up to 40A?
Please read the first post(s) of this thread.
LEDs can be driven past the recommended manufacturer specifications.
This is what enthusiasts do and is the entire point of this topic, if you even read the first post.
I see.So,I wish some of you can put it in a GT,test it and share the specs with us,so as others follow. 
Thank you all.
Are you not aware that this has already been done? Vinh over at Skylumen has built several GT’s with this emitter. His posts are mainly on CPF.
Over here, Lexel has already fitted it into a GT, check out this thread.
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You forget that I live in Greece,so there are some thousands of miles between me and Vinh,plus the Greek Customs which are very strict, charging much money.Also,I read that Vinh drives the led to 20A,so I don’t know if it is good for me to pay much for little.
If I see that some guy goes to the transfer, with for example a Lexel driver,and I see some photos of this,then I can tell a Greek modder, giorgoskok, and a BLF member as well,to make the job for me. He has upgraded many lights for me till now very well.
Thank you anyway for your response.
Thanks to Web Plot Digitizer I finally reverse-engineered the chart from the Xandre’s test and got some efficacy estimations.
125 lm/W at 700 lm
110 lm/W at 1400 lm
85 lm/W at 2800 lm
58.5 lm/W at 4650 lm (this one is actually provided directly, not reversed)
32 lm/W at 5650 lm
Overall….worse than I expected.
Yeah, it was not designed for efficiency like a Prius car. This is a straight up hot rod. A twin turbo hemi type emitter designed to battle HID bulbs. Lol
If you think this efficiency is bad then go calculate it for the CBT140 
I did calculate it for dedomed SST-40. It was good. This one is better thermally. And factory flat instead of hand-sliced. And much costlier which enables a variety of improvements.
Despite that - it’s much less efficient……