High drain cells and DD drivers are not good combination for low Vf LEDs like Luxeon V and many new Nichias,Crees... But it's nice too see that it can survive for quite a bit of time under way over spec conditions, most other LEDs just turn blue and die.
The Luxeon V is one tough emitter, it’s still working after all the abuse and after I sliced the dome the dark spot is less visible. I did put a new Luxeon V in the Sofirn but this time I used a LD-B4 6 Amp driver instead.
As long as you use a host with good thermal path it’s hard to get the Luxeon V to turn blue, I have only managed to do it in a Skilhunt H02 with a FET driver.
I have a LD driver with luxeon configured it in DD mode on turbo. on fresh battery it never takes more than 8A.
In the Sofirn C8 I just put together with a LD-B4 using 22AWG wires from the driver to the LED and a high current spring without bypass I get 5.64A on CC and 9.36A on DD with a Sony VTC5A.
Will it be okay to push 7A regulated current with this LED? How will it hold up in the long run with regular turbo runs? External OTP will be done with L4P driver and MCPCB.
7A should be fine although my sweetspot would be 6.
No one knows what happens in the long run until reports are coming in that Luxeon V’s are failing. At least my tests do not tell what happens when leds are overdriven longterm.
Thanks djozz
Pretty much all my Luxeon V lights have lost amps and output - thought this was known well? I'm gonna convert what remains over to something else.
How dramatic are the losses? Could you talk about how you ran them? Were they DD’d, etc.?
Oh boy, @work now, but again, thought this was common knowledge. Initially in a SD Mini w/FET+1, the V did 8.5A on a GA cell at 4.16V, ~2200 lumens at start, 2000 at 30 secs. Now I think it's down to ~1500 lumens, not sure of amps. Think it's in my notebook somewhere but I don't have a cross ref to find it easy.... No time now to research.
Again, though everyone knew this? Anyone knows of it? Am I crazy?? 
I don’t think driving this LED with FET is a good idea. I lost half of my output (physically two of the 4 four emitting surfaces stopped working) using a LD-A4 driver. I had high mode set to direct drive and it was a huge mistake. Had to replace the LED. Currently, I’m running high mode constant current at 5.25A.
It’s been months of heavy use and lots of turbo runs and it’s still as it was since I tested it after the new LED was installed.
Ahh, ok - that helps somewhat. Soooo, I take it running/testing at 8-10 amps wasn't good? Didn't know there were 4 separate emitting surfaces - need to take a closer look at mine.
I hadn't heard of it. My D4 is using Luxeon V and still doing quite well AFAIK. Of course, that's a bit different than direct driving a single emitter. I should do a test with the bezel open and measure the voltage across the LEDs, since I don't have any good way to measure current (especially current that high).
A single Luxeon V that’s FET driven with proper springs or bypasses is not a good idea. VERY bright, for a VERY short time.
It’s a news to me that this LED has problems with sustained FET use.
It’s also a news to me this LED has 4 dies.
So…thank you both for your reports. 
In a quad, probably 5 amp per LED at best, so sounds like it's still in the safe zone. 20 amps is pretty high for typical compact quads.
So guess for those using the V's on a quad, you reflowed the 4040 V onto 3535 pads? I was only using L4P's 4040 MCPCB's.
I missed this. A bit confused: Is the Luxeon V 4 dies?
Ohhh - that 4040 quad is not listed under his MCPCB's, so guess he doesn't sell them bare :facepalm:
Yep, I'm still confused bout the 4 dies as well.
And since a couple guys chimed in about running these at high amps, djozz is either unaware, or didn't take time time to update his OP, because reading the OP, everything is fine and dandy with the Luxeon V at up to 12 amps or so...
Certainly that L4P quad or triple seems to be the best way to go with these LED's, or, be sure you constrain the amps way down, under 6 I suppose.
MOSLED EXTREME ( mosX ) ceramic insulation 4XV 4040 quad MCPCB (BARE) is here:
https://led4power.com/product/mosled-extreme-mosx-ceramic-insulation-4xv-4040-quad-mcpcb-20mm/
It is on page 2 and easy to miss. Can only find the AL version though.
Lumileds claims that Luxen V has a single die:
https://www.lumileds.com/news/299/50/Lumileds-Transforms-High-Power-Category-with-1-700-Lumen-Single-Die-LED
KevinZA1988 do you have any pictures of the failed LED?