I never direct drive a XML-U2 led before and i would like to try it 
host im using is unknown at this point, my question is since i only have 18650 battery’s/18650 hosts how many 18650’s should i use ? or how many volts should i put to it
the led is re-flowed on to a copper sinkpad and on a 1inch thick copper slug
No more than one 18650.
A fully charged cell might overdrive it, so a cell at 4.00-4.10V should deliver plenty current, along with the voltage drop.
ill try only one 18650 and ill post few pics later of the build
Either one really good (IMR) or several cells in parallel. No series, unless you want to fry something. :P
its not the voltage thats a problem, but the current may fry the led in seconds depending on how much the battery can put out
As Bort said, the main issue in DD is Current … not volts, as you cannot run 18650s in series for DD anyway (will definitely damage your XML).
I’ve DD’d a couple of XML-U2 lights, including a Crelant 7G9 and an Elektrolumens EDC XML, without frying the LED. However their wiring was “sub-standard” in that I used small gauge wires to increase resistance in the entire circuit so as not to damage the LED.
On the other hand, I’ve tried another DD XML-U2 project using very good electrical components and low resistance wires, and “insta-flashed” the XML-U2 … I tried this TWICE, having not learned my lesson!!
Related to this is the number of batteries in parallel - the more batteries in parallel the more current they can supply (less load on each), which will also be a problem depending on whether you’re trying to DD with low-resistance wiring. A good example is my Crelant 7G9 DD I mentioned above - it runs perfectly (and brightly!) on 2 parallel 18650s … but if I use 3 18650s it will start to dim and the light will become bluish in colour after about 10 - 15 secs as there’s just too much current running to the LED.
Cheers … and good luck with you build mate!
You can't look at match's XM-L2 on Sinkpad Vf chart at the moment because he removed it from his thread (he did not trust the meter he used to do the measurements, I'm waiting for the corrected chart ), but if the measurements are correct after all, you should be able to direct drive the XM-L2 on copper+good heatsinking without destroying it. If your batteries can deliver it and maintain their voltage under such load, the led will draw max. 5 amps.
a lot of assumptions are inherent in your post, must be xm-l2, must be sinkpad or equivalent, must be a similar LED to match’s (there is voltage variation in a batch) and must have heatsinking enough to lower the LED to near ambient temp (like match’s huge block of metal setup)
Also battery chemistry, internal resistance, age of battery and charge voltage (4.3V cells) could combine to put out enough current to ruin the LED
Fasttech makes a direct drive:
http://www.fasttech.com/products/1612/10001535/1114500
Also, the East 092 is DD
I get about 3.3 amp out of one 18650 on the East.@ 4.2 volts.
Has anyone used either of the boards ?
The East 092 in the HD2010 is direct drive in high, but it’s relying on very small wiring and switch resistance to protect the emitter. Ask me how I know….I soldered a 20ga wire into the bottom spring today and fried my emitter in about 3 seconds with a LiNiMnCo 26650 cell in place at 4.15V.
By the way, the switch is rated for 1.5A. I had been getting ~1.24A at the tail before I did the spring, everyone else was saying they were getting over 4A, guess I found out the hard way…should’ve put an 18650 in for a trial run.
Ouch, sorry to hear that.
I do think it’s rare to fry your emitter by DD, however.
May be the first time I heard this.
Edit: I’m stupid… S)
Similar to Dale, without the smoke, I discovered that a good solid 18650 can really pump the amps into a single XM-L. With a fully charged Sanyo UR18650ZT, I get 5.7A at the tailcap; no driver spring mod. I think I’d smoke it for sure with the driver spring braided. The spring gets really hot too. J)
In normal use, I put laptop pulls in my HD2010s until I decide what driver to put in them when they get the XM-L2 on copper treatment. I may leave the East-092 and see what I get for DD current. Hopefully more than 4A.
I get around 5.2 amps with trustfire flame 3000’s direct driven on all my xml’s ive tried.
fwiw.
Chris
Yeah, the XML is easy to kill. The XML2 not that easy..
Yes, I have both. Answers:
The EAST 092 I got was not direct drive on high (only on SOS and strobe). It was around 1,8A on high. I got a refund from fasttech.
Thread about the “low output” EAST 092 from Fasttech here. Fasttech said they would get the one they had in the picture again, which should hopefully be direct drive on high. I have another one one the way. Currently, they are out of stock though.
As for the cheaper one. Mine was not direct drive, but pulled a bit over 3A on fully charged batteries. That soon went below 3A. Mine also had next mode memory.
Others have different experiences with it. So consistency seems to be bad.
While on the subject, I have some questions.
-Once I tried 3x NCR18650B in series in direct drive with 3 XM-L T6 in series. Killed a LED in about 10 sec. (5+ amps)
Would the result have been the same with 1 battery and one led?
-Anyone have a clue how many amps a Feilong ICR 32600 will push out in direct drive on high?
Im considering to try it on 4 or maybe 5 XP-Gs in parallel, but I do not want to kill all the emitters instantly.
I plan to try it with the hopefully direct drive EAST 092 I have on the way from fasttech. Would the driver survive that?
-Just curious if anyone have tried say 4 XPGs combined with say 1XML or 1XP-E. All wired in direct drive (parallel). Could there be an issue combining several different emitters with slightly different forward voltage?
I have a WW MC-E direct driven of a TF 26650. It pulls 4.8A out of a fresh battery, XP-G2 pulls 2.8A out of NCR18650A but gets really angry in about 10 seconds. Should have tried copper PCB.
Thanks NightCrawl, makes me feel better about the XM-L2 I just put on a copper SinkPAD.