nice info,thanks.
Thanks RaceR86 again for the effort put in here. It appears the trend here is that the XPL is the new go to emitter for very hi current draw applications. It would be interesting to compare light output but with the smaller die of the XPL the same reflector could not be used. This is where a sphere would come in handy.
Thank you for the testing.
It is nice to see that it is highly unlikely to blow a led up with a single battery setup.
Thanks you RaceR86 for the tests and datas.
May be multiple emitter in parallel will become more popular, hoping battery technology will make big improvement too.
Thanks for more and more insightful data, RaceR! Who would have thought that led voltages, so relevant for single-cell flashlights, would vary so much. And there is no precise specification of Vf by any seller including Cree itself!
With a really powerful buck driver I would put my money on the XP-L based on what I have seen so far. Buying new XM-L2`s (from recent batches) and trying to push them to the more extreme currents seems a bit like gambling with bad odds. Unless you have verified how far the emitter can be pushed, which I now seem capable of testing quite well without frying any emitters. :) Sadly, most XM-L2s from recent batches does not seem that capable.
Not sure I understood everything you said. Smaller die on the XP-L? XM-L and XP-L have the same die size. Suitable XP locating/centering ring can make the XP-L`s fit perfectly in any reflector that you use XM-L if you need one.
I disagree.
If DD and low resistance cells could push XM-L2`s and XP-L`s to death at 5,5-8A+ that would be a good thing IMO. If the emitters were like that, many lights could maintain 3A much longer. Good for everyone who wanted a bright light.
Hot rodders could make single cell hotrods like say an HD2010 with spring mod with a 5200mAh cell push 6A to to an XP-L and maintain that for say 30% of the runtime before it started to decrease.
The" Vf safety net" we have are holding us back IMO. This is quite evident in the increasing increasing amount of "low resistanse mods" we are seeing. People just cant get "high enough" with regular cells. Not even with low resistance cells...
Id much rather see some lower Vf emitters. If the XP-L had a Vf of 3,2V instead of 3,43V @ 3A (25C) then I don`t think the XM-L2 would be used much.
When that is said, there is a place and use for every emitter/driver combo depending on what people want. Just need to find the best. :)
I was a bit surprised when looking at the highest and lowest amp readings. Still not sure if de-doming can change things a bit though.
I have seen and reported Vf issues before though. Check out OP in the L4 mod thread and scroll down to "Why did I use a bunch of time modding this light for probably zero visible gain?".
Cree have lots of precise data. You can see Vf here for any given emitter at any given current and temperature. My spreadsheet data is actually very close to Cree`s data. At least if you average out the numbers.... Lots of the numbers are within 1%. Problem is, +/- 5% can give large differences in flashlights.
Earlier in this thread I assumed the XM-L2s had Vf of 3,33V at 3A. And it does, at 85C. My testing is basically at 25C based on mcpcb temperature.
To give a few examples at 25C Cree says Vf are:
XP-G2 @ 1A : 3,16V
XM-L2 @ 3A : 3,43V (3,02V @ 1A)
XP-L @ 3A : 3,48V (3,06V @1A)
Added following emitters to the spreadsheet. They are in "bold".
| EE X6 - BLF Special E. | XM-L2 U2 3C |
| Intl- Outdoor | XM-L2 U2 3C |
| Intl- Outdoor | XP-L V6 3D |
I tried to do a light output comparison between three emitters but my test setup were not good enough to get any useful data.
Any thoughts on the different voltages on the XML-2 3C leds?
Thanks for more data RaceR86.
In high hopes to build a ~2000lm XM-L2 build, I ended up trying to find a suitable LED… 6 XM-L2’s (U2, T6 and 1 U3) and 1 XM-L U2 later… Nothing survived past 7.6A! Even when below 4.2v. The U3 mentioned above did 7A, but died when hooked up to a stock HX-1175b1 (dumb). No real data other than vf/A on a really promising XM-L2 that died at 7.6A. Oh well…
I bought some of the T6’s mentioned above and a couple more U3’s. I may try a couple of the T6’s to do 8A, but will have to settle for less powah! I have a P-bin CBT-90 and SBT-70 screaming in the drawer… Pick ME!! Unfortunately the vf of the CBT-90 @ 18A is 4.3v, was hoping for less. It should be making between 2500-3000 of very inefficient LED lumens though.
I also bought a light meter, so I should be able to start measuring output as soon as I get a light meter built and calibrated.
But everybody has been doing low res mods for years. Many years.
And I still like a direct drive light. Hands down it is my favorite. So as far as I am concerned its still good.
Sure it was, really, funny to see a single XM-L light pull 8 amps from a low resistance setup with a good cell.
But the output was just not there compared to the XM-L2 led at lower amps. Back then we all vailed and carried on about whether it (XM-L2) would be the end of single cell lights. It was not.
And I still have enough Xm-L lights left over to test it. But nothing I measure is calibrated by any method commonly acknowledged or understood explainable on the forum. So I can only say that relatively speaking a XM-L light doing 5A is about equal to a XM-L2 light doing about 3,8A. For anyone caring that amounts to about 1360 lumens in my converted Ikea bucket of light.
As far as XP-L vs XM-L2 then the only tests (in a single thread as far as I remember) that has light output included are done by hpflexpro where they are equal. So of course it is brighter to have a higher amperage capable XP-L. I understand that. But it is a little marginal to me.
I can't believe I said that. I may have to find another hobby. Things are shifting in my world. Sorry for intruding. I'll sod off now.
I don't know how I missed this thread until now, but I hadn't seen it until today.
I do think that the newer batches of emitters are different than the older ones--and not just the U3 bins, but the T6 and U2 as well. I've seen the vF shift in the newer batches of T6 4C emitters as well. They just can't pull the amps like the old emitters could.
That said, the higher bins seem to put out more light at less amps, so all is not lost. I wish we could have more efficiency and higher amps, but I guess we will have to wait.
I now have a 10A linear power supply (extremely small ripple current--basically non-existent) and the newer emitters just can't be cranked up as high as the older ones. 7A is difficult with a lot of them, even with a very smooth output.
With a stock HX1175B1 you are almost guaranteed to blow any XM-L2 you hook up to it--especially a newer batch XM-L2. It puts out around 7.5A stock and has a lot of voltage ripple on top of that.
H'mm and here I sit thinking you were keeping silent on this. Shame on my thoughts.
Thanks for your input RMM. What power supply did you end up with?
Unfortunately I haven't been keeping good notes on things--I've been too busy and burned out to do it right, but I have built 30-50 lights with these newer batches--lights that I've built with the old emitters as well--so I've been able to see the differences in lumens and amp draws.
I ended up with a Yihua PS-3010D. It's a beast of a power supply, and a great price, but it has some flaws from the factory:
- The current measurement display is not calibrated correctly. Simply remove the face plate and calibrate with a known load or source (I used 2x 0.5 ohm resistors in series, along with two multimeters to check voltage drop and total voltage).
- The chasis ground was not great. Fix while you have it apart.
- The output will spike sometimes if the power is turned on and off. This is also easily fixed by adding an extra capacitor to the board (see video link for overview and all of these fixes).
Fixes video:
http://www.youtube.com/embed/Osc1--tmzlQ
If you need a high-output power supply on the cheap, then this thing delivers. Nice smooth output--and lots of it. Be prepared to make the fixes shown in the video. It is large, heavy, and loud, but nothing else in the price range even comes close.
[quote=MRsDNF]
Any thoughts on the different voltages on the XML-2 3C leds?
[/quote]
The emitter from the EE X6 was still attached to the pill and stock copper mcpcb in the flashlight since some thermal adhesive was used and I did not plan on swapping it. Voltage was very similar to the CW XM-L2 U2`s that fried below 6A. Im guessing it might have been good for around 6A. It had fairly typical voltage for a "new" XM-L2, but slightly on the "low" side. When I say "low", i mean closer to the "good ol emitters"
The U2 3C from IOS had very high Vf. This was actually higher compared to the XP-L V6, which is just wrong. Id guess I was just extra unlucky with that one.
I think they just represent two sides of what we risk to see when buying XM-L2s. I would not bother using any of those with the H6Flex at "full throttle".
:beer:
Sorry to hear about your U3. Ive had 8,2A out from a stock (resistor modded) HX 1175B, but that is pushing it. It was a temporary test with an old XM-L2 T6. Its nice to see your U3 handled up to 7,6A though. Just strengthens my theory that low Vf emitters are more capable of higher amps before they fry. I knew you had a winner. Not a single one of the emitters Ive bought lately would have been capable of that.
7,6A though a stock HX-1175B in general is gambling no matter how good the emitter is though.. Id recommend XP-L @ 7A and a HX-1175B modified for low ripple next time you want to push the limits.
@ Ledsmoke.
Feel free to stay and share your thoughts. Btw, are you tired of living up to your username or something? :D I find the data very useful. Helps to avoid any damaged LED`s and learn more about the headroom. Also, in single cell DD/linear lights Ive been really enjoying to use the emitters I had data on. They performed just like expected in terms of amp draw. Often when making such lights there are lots of differences in peak amp. Sometimes its hard to pinpoint exactly why, but knowing the behavior of a certain LED just makes everything clear and simple. :) There is usually little or no more guesswork on the weak link. I can then handpick LED`s for the type of driver they suit best.
@ RMM
Thanks for sharing. Sounds like your experience go hand in hand with my data and experience.
Btw, here is a power supply similar to mine:
I got mine for close to nothing. It had been used in a professional work environment. Its really big an its heavy, that I know. Anyone familiar with Farnell? Just curious...
What is the correct term for forward voltage btw?
Vf?
vF?
vf?
VF?
^ Interested in hearing feed back on the Farnell too.
Just wanted to thank you again for all the effort you have put into this research and reporting RaceR86. Very good information and I hope it eventually leads to discovering the underlying cause of this new issue with xm-l2's. If not, atleast we have some potential clues for identifying the more vulnerable emitters.
Cheers 4Wheelr!
I do agree that the higher vF emitters can't take as much peak amperage. I suspect that the peak voltage all of the XM-L2s can take is similar before they blow, but it takes more voltage to get there if the forward voltage is higher so you hit that limit with less amps.
Its does not seem too far from the truth, but there is some strange stuff going on. Look at "RIP V" in the spreadsheet.
XM-L2 U3 went all the way to 4,27V. Most U2`s said farewell around 4,05 (+/- 0,07v). Something strange with that U3. Djozz`s U3 were quite similar. I dont know what to make of the U3. I dont like to push any of the XM-L2s beyond 4V. That is danger zone. But maybe not so dangerous for U3???
When it comes to new T6 and all U2`s Ive tested. If the Vf is 3,78 @ 5A or higher, then its not suitable for really high amps. If its 3,7V or lower, then its good.
RMM, have you come across any XP-Ls that could not handle 7A? Or have you noticed any with extra high Vf compared to the average? So far everything I have seen seems quite predictable and fairly consistent.
Did a quick test on two emitters from the Supbeam X60. I stopped testing at 3 and 5A. Not suitable for really high amps. I have not added them to the spreadsheet. One were bad the other one were really horrible.
If anyone at some point stumbles on a batch of high binned XM-L2`s (preferably U3 if CW, or U2 if NW) with consistent low Vf, let me/us know..
I haven't tried pushing the single XP-Ls as hard simply because I don't have any lights that I've wanted to put them in yet. 99% of the XP-Ls I use go into small triples with a single cell where vF is not an issue.
This is anecdotal but Hank (from IOS) told me that in the emitters he's tested the XP-Ls could go up to 1A higher than the newer XM-L2s. What I don't know is if the process or construction has or change on the XP-Ls to match the newer XM-L2s but we just haven't seen those emitters yet.