I might remember it wrong but I thought I have red that 0.4 volt difference will be enough for some buck regulator’s.
Could also have been for a different type driver…
Thanks for the test!
A buck driver is always possible, but doesn’t always make sense. Most stock single-cell lights with 3V LED (XM-L2 for exmaple) have a buck driver. A lower VF means that the output stays constant for higher percentage of the runtime and the average current pulled from the battery is lower. So the lower the Vf, the more sense a buck driver makes.
Definitely interested in this as a Q8 mod candidate. Thanks a lot for all of the information djozz! 
You could maintain efficiency with a boost driver running these in series correct? I’ve been getting too many ideas lately, not good for the wallet.
why use this led in 1000 lumen light, i mean, if you want 1000 lumen, go with xpl-hi,hd, xm-l2, or even xp-g3, and it’s also easier to reflow the led on MCPCB
if i use this led, i will push it over 1800, close to 2000 lumen(or even higher)
It’s more efficient and produces a beam with a more even tint. Those are big benefits.
LEDs are more efficient when they are driven softly (look at the slope of the graph in the OP). So to acheive 1000Lm, a “2000Lm” LED driven at 50% will be more efficient than a 1000Lm LED driven at 100%.
Djozz, ylu know this was bound to come…please do the Q8 with these?
For me newbie it is kind of mixed.
On the one hand lots of lumens, on the other driver burning off volts. (And end Ferry Mingele mode 
)
If these are a good Q8 candidate, we really should have the XML pad ledboard redesigned to have pads for this as well.
XML and XHP70 would not fit, but these small pads would.
Hmm, ok, I will mod a Q8 with these, but I may wait for the new ones to do that. But mind that the stock light puts out 5000 lumen at 20A, and with Luxeon Z’s it is 8000 lumen at 36A, it will get kind of way too hot.
Thanks for the test djozz. Need to get you some samples of XP-L2. I’d donate to the cause. Impressive that the 4000k Luxeon V has almost identical output to a 6500k SST-40, and at a lower voltage to boot. Tint looks wonderful too! Can’t wait for some high CRI and more color temps.
How much does a custom run of DTP copper boards usually cost?
…and :+1: :+1: :+1: Lumileds of course.
Very interesting LED.
Maybe start a ‘groupbuy feeler’ thread.
But Djozz, how off is the size for an XM board?
Looks as if it could fit just as good bad as on an XP board…
The Luxeon V will not fit XM-boards at all.
I just posted over on RMMs thread to see if he has any plans to stock the Luxeon V and perhaps even get some custom DTP boards made up for it. He has his MTN Quad boards which are top notch, so if he did a Luxeon V board I would be in for quite a few. A triple or quad Luxeon V board would be really interesting as well.
Wow! Nice job on this test!
Exciting. If Vf's get a bit lower, one could nicely buck drive 4S emitters with 4S cells.
Thank you for another great contribution to the hobby.
16mm DTP
8) 8) :sunglasses:
When will they be on your website? I’d like a few of those.
Send me your address to PM, I wanted to send you a few anyway.
:+1: PM sent. I will do a new Luxeon V test on this boards and am really curious how much different it is. My guess: slightly better performance but way easier reflow!!
Have you tried a Luxeon V in a flashlight yet and if so, what is your experience?
Will that be for sale on your website soon? Looks good! Really want to see this emitters potential on a properly sized board.