Really basic, but installed an XM-L2 4C in my Olight S1R. I will use it more often now. Next is the S1A… will either be a 4C or 5A.
I’m really frustrated right now.
I’m finally getting to work on my L2, and the driver build went so smoothly I was practically dancing in my office. I tried dedoming and XM-L2 U3 by mixing a few methods, and the emitter came out incredibly clean. I get it all built turn it on, and it works perfectly. I pull the tail off and hook up my clamp meter to get a reading, tap the button to get to turbo, measure 5.25A and… pop. :rage:
So I assume the bond wires must have been invisibly damaged with my special dedome method. A bit annoying, but whatever. I reflow a new emitter, and just drop it in gas to let it go the old fashioned way. It comes out not perfect, but good enough. Work s great on the power supply, so I get to rebuilding the L2. I have a short somewhere and I can’t figure it out. 45min later it seems it’s finally good. I fire it up, it works great. Turbo is even brighter than before :laughing: So I take the tail off to see what I’m getting with the clamp, tap the button to get to turbo, measure 5.4A and… pop. :rage: :rage: :zipper_mouth_face:
I’ve never had this happen. Never. :weary:
I’m using a Basen cell with a Sir800dp for the first time. I haven’t bypassed the tail spring yet. I can only assume that the resistance of the tail spring kept it from popping in the light, then my thick wire I use with the clamp was just too much.
That sounds really frustrating. I have heard of some XML2s tending to fail. Here is a thread with some other’s experiences.
Hmm thanks for that, didn’t pay attention to it before. I guess now I’m waiting for a new emitter on the slow boat from China.
I have a couple of XM-L2 U2 on order to replace fake XM-Ls in a 7x SRK. Hope I won’t hear pop-pop-pop-pop-pop-pop-pop with FET+1 and 30Q …
I dont think you will reach more than 5A/led. One 26650 to one led is much more than 4x18650 to 7 leds.
Pd it has to do something with U3’s…
Burned 2 in my C8 , running at 4.9 amps… Perfectly clean dedone
I need some opinions guys, or maybe even some data :student:
How much power can I continuously run through a red XP-E with no heatsinking without damaging the emitter?
I mean aluminum MCPCB just floating in mid air in a pill. Can I get away with 350ma? I tested a white XP-E2 at 360ma and the mcpcb got really really hot, but after 2min there was no sign of it turning blue.
Well it looks like you are in the perfect position to take some data. 
The red XPE has a thermal resistance of 8 C/W. 0.35A(2.1V)=0.735W, so the LED junction would be 5.9C above the MCPCB temp, assuming there is a DTP. If no DTP, the thermal resistance might be significantly higher.
I just did some measurements with an XPG on 16mm Al MCPCB at 2.7V and 0.3A which is 0.8W. The back of the MCPCB gets to around 75C sitting in open air. So if your XPE were on a DTP MCPCB the junction would get to ~81C which shouldn’t do any damage.
Thanks for testing that!
So the red will run at 350ma below 2v, so thats only about 0.7w so that’s in my favor.
However I’ve heard the red XP-E is more affected by heat, it won’t be as efficient as the XP-G (so more heat?), and there’s leas cooling in a sealed pill than on a workbench.
So with all of that, do you think I’m still good with 350ma,or should I dial it back to like 200ma?
My pleasure. Yeah, I guess 0.2A would be safer with the unknown resistance of the non-DTP. Is it really not touching anything in the pill?
Well, it’s a 12mm mcpcb that’s been cut down to a narrow strip, still 12mm long but barely wider than the emitter itself. It has some small contact with the side of a pcb and the lip of a brass retaining ring. It’s packed in a small space, but it’s not actually pressed against anything.
Oh, it sounds like there is a lot less surface area than the MCPCB I tested with. I think it should get considerably hotter in this case, so maybe try .2A and see how it goes.
Try some heavy wire to the pads if you can. Heat will go through there too.
Unfortunately no room for that, just some 26awg. Maybe I can pot the top of the board a bit, but 200ma is plenty, just wanted to see how far I could push it
Here we go again…
BLF X5
You beat me to it :rage:
I guess I’ll have to go bigger….
Had a really frustrating morning trying to make a 22mm FET+7135 driver with zener mod, using the components from a BLF-A6 driver, a 22mm wight board from Oshpark, a zener diode and a 220 Ohm resistor. I will not go into details but in the process of troubleshooting I must have soldered and desoldered (by hand) at least 30 almost invisible parts to the board. And it never worked. And it was part of a nice mod that I can not do now 
To cheer myself up I skipped the project and went on to another mod that to my surprise became a total succes. The host is an ultra lightweight 4.5 dollar AA zoomie: Ultrafire AT-007, one of my favorite cheapies because of the compact build but still good lens and optical path.
*The led is a dedomed XP-G2 S3 3D on a Noctigon. I sanded the Noctigon to 1mm thickness to get the focus right, it is clamped with the stock plastic thingy (that I made black with a marker) over the hollow pill (I love hollow pills :partying_face: ), bit of Arctic Silver on the edge of the board for better contact to the rim of the pill.
*The driver is a 15mm diameter Bistro driver, I transferred the components of a Banggood Bistro-driver to a 15mm Oshpark FET+1 board (I believe a design by Warhawk), and it works flawlessly. After the failure this morning that came as a total surprise.
*The tail spring was bypassed, the pressed-in switch-tab received an extra solder blob on the side for extra tight fit and improved electrical contact with the body.
And it works, and does not even get incredibly hot too fast, even on max setting.
Numbers on highest setting and purple Efest 14500:
–3.75 A current and quite constant for the first minute. This is measured with a clamp meter around a thick copper loop, the light without tail.
–450lm flood at start, 422lm at 30 seconds, the high setting appears pretty stable, at least for a useful minute or so . So just 7% drop, did I mention that like hollow pills? 
–33kcd throw after 30 seconds, measured at 7 meter. Nice for a just 18mm diameter lens.
-and a good tint, this led dedomed gives the best dedomed tint around IMO.
So although meant as a freak light with too much power in a flimsy host, it just works and is a great EDC, and anything with bistro is pleasant to use . And if throw/gram is a quality for a flashlight, this light scores 0.89 kcd/g (without battery, with battery it is 0.58 kcd/g). Beat that!
Edit: just checked and unexpected by me my Brinyte B158 with dedomed S4 2B has better kcd/g, with battery it is 1.07kcd/g LOL
Pop-pop-pop-pop-pop-pop-pop
That’s what my 7x SRK did a couple of minutes ago.
Did some crash testing with this light. Mounted a FET+1 on the empty stock PCB, springs have been brigded earlier, the traces on the tail PCB have been strengthened. There were 6 fake XM-L on the MCPCB and 1 spare Cree XM-L2, since one of the fakes died earlier.
Measured 18 Amps for more than 4000 lumens with old Keeppower 2900 protected, and then I tried my new 30Q. Was able to measure 26 Amps but this might have been a little to much … 
After less than 10 seconds all LEDs died. Actually I am not surprised, I expected something like this. New Cree LEDs are on the way.
Wow, sounds dramatic. Was there adequate thermal path and do you think that was the cause of the failures?