Teardown and Mod Thread of Courui XML2 Aka "Big Head 3x18650 Side-Switch Thrower"

It is a massively nicer beam than when I started and the HD2010 should be a good comparison if you know what that beam can look like.
But I should state that beam shots like these can be a bit deceiving. They don’t look quite so flawless in person unfortunately.

In person you will see more shall we say “artefacts” around the center hotspot. This is usually in the form of like a flower petal type halo around the center hotspot, as well as sometimes a faint ring just at the far extent of that flower petal. This stuff is comparatively so much dimmer than the hotspot that the camera with it’s limited dynamic range fails to show it accurately. Our eyes pick it up though.

It all depends on how well focused and centered the emitter is in the reflector as well as the reflector type and quality but if you combine a smooth reflector with a square emitter those artifacts are always going to be there to a greater or lesser extent.

So both these lights exhibit these effects when looking at the beam on a white wall, on the HD2010 with it’s softer hotspot transition it’s only really noticeable when spinning the light and watching the center of the hotspot. On the Bighead the flowerpetal is a little more obvious, I suspect simply as a side-effect of the enhanced definition of the hotspot itself. The ring is also slightly more defined. But this is all with just a quick 5minute focusing so that may still be improvable by further tweaking.

The HD2010 took considerably longer than this to get to the “perfect” focus and alignment…like hours… :stuck_out_tongue: :slight_smile:

Outside you’ll never notice either of these artifacts so ultimately it doesn’t really matter.
I just want to say that if you expect a buttery smooth hotspot when white-wall hunting, you’ll have to settle for less throw and go with an orange peel reflector!

Cheers

I wonder if the 5a ramping lck led driver could be peesuaded to fit?

from the quoted size, I’d say so but it depends on the positive pcd. comfychair has one so perhaps he could give us a measurement to compare to the stock board?

Yep plenty of space in the driver cavity. You’re going to struggle soldering anything to the aluminium shelf. But you could simply bolt a copper or aluminium slug to the bottom of the emitter shelf/pill and try to size it (or alu/copper foil wrap it) so it’s a press fit into the driver cavity. Then you have some more heatsink mass on the bottom of the emitter shelf and an extra thermal path from there into the walls of the driver cavity/head. Kinda like I did here with my Apex 5T6 here that light had a similar issue with a “floating” driver shelf/pcb.

I’m looking forward to seeing what people come up with to rectify the problems with this light! :slight_smile:

I measured the inside diameter of the stock driver board ground ring at 32mm. That’s the gold ring on the top of the board, the inside diameter of the driver cavity is probably ~34mm/35mm going from that measurement. I’ll get accurate measurements for this when I have the light apart again tomorrow.
So it might just work…

Personally I’m not going to go for multi cell setups on this light, it’s parallel and I like it like that :slight_smile:

1.504"/38.2mm OD, .562"/14.3mm thick. This one also needs more than 4.2v, and also won't run anything but a "3 volt" LED - it's not a buck driver despite the input voltage range.

Of course. Sorry I didn't add all the required health and safety disclaimers! NOTE: SOME ASSEMBLY REQUIRED, TOOLS NOT INCLUDED, WARRANTY VOID IF REMOVED

fair enough. for some reason I thought this one played nice at 4.2v. I’ll go back to sleep :bigsmile:

What’s driving your HD2010? Is it direct drive?

Pretty much, it’s a heavily stacked 7135 driver that will do max 6A. But in reality it only managed 5.8ish on a brand new battery. Generally on a fresh-ish cell it will hit around 5.5A. In that image it was probably doing closer to 5A.
The emitter is an XML U2-1C btw so higher currents are easier than with an XML2, even on Trustfire 26650s.

The HD2010 has somewhat brighter spill and a wider spot so comparing side by side is going to be tricky. But the bighead can definitely project a tighter and arguably brighter spot even in stock form with the tweaked centering ring. Can’t wait to see what it will do when really driven hard!

Hotspot size comparison between the two is fairly close to the difference between a domed and dedomed XML HD2010.

Thanks Linus. I might just go back to XM-Ls for hard driven single cell lights.
I’m waiting to see if you try a resister mod on that driver.

Will give it a shot tomorow.

3x good 18650s even while feeding 6A to the emitter are going to be able to maintain a much higher voltage than even the best 26650 cell I would think. They’ll only be loaded with 2A each and that should be easy going for most good 18650s nowadays. And even Samsung 20Rs have decent capacity if you can use 3! :wink:

This combination should be enough for driving an XM-L2s well to 6A, so I think they are the way to go in this light.
For something like a HD2010 with a single 26650 I agree you might just get better drive current and higher overall performance out of an XML U3 or similar rather than an XML2 U2. Would love to see some tests to back this theory up though! :slight_smile:

But... if XML & XML2 were equal output at equal currents, then sure, whichever one would pull the most current would be the go-to choice, but they're not.

I just popped my an E-Moli 26700 into my other HD2010 with the same East-92 driver but with the stock XM-L T6 and got 4.7A. A big improvement from the XM-L2 using the same cell.
I don’t really like tail readings much because the current levels jump around too much as compared to an emitter reading that is more stable using alligator clips rather than hand pressed leads.

Sure I understand that XML2 are about 20% more efficient at the same driver current, and that’s quite a lot more lumens…but is that really how it works out in the real world when the driver current drops a considerable amount due to battery sag. Diminishing returns on the XML at higher currents will probably rule the day, but I’m still curious.

I don’t really have enough experience with XM-L2s to know myself so I’m just curious if someone has directly put this theory to the test.
Say has someone done a direct lumens/output over runtime comparison on the same superbly copper heatsinked light like a HD2010 with the same battery to see which comes out on top. XM-L U3 vs XM-L2 U2 in direct drive showdown! :stuck_out_tongue:

In any case it probably doesn’t matter since XMLs won’t be available for much longer anyway.

The thing is though, you’d have to measure the actual lumen output difference not just the current. You may be driving the XML-T6 with more current but that old T6 is far less efficient at turning that current into Lumens than say an XM-L2 U2 and even 20% less effecient than the equivalent XM-L2 T6. This gap is probably far too big to jump with higher current alone. Closer bins and proper lumen measurements are where it potentially get’s more interesting…:slight_smile:

Boy. Am I ever getting confused.

I don’t blame you, splitting hairs is a confusing and complicated business :stuck_out_tongue: :bigsmile:

Yeah I know, cheating, it's not apples-to-apples unless it's on a XML board, but why go only halfway?

Another thing, semi-serious, stay away from copper MCPCBs if you want max amp draws. On aluminum the LED runs hotter and therefore pulls more current. Shouldn't it put out more light if the current is higher? No? :)

Thanks for the nice teardown Linus! This light will still be on my watchlist of lights very interested in.. (Im not pulling the trigger yet though)

Hopefully all info below will clarify some for those who have missed some of the info around XM-L vs XM-L2.

Having 3 cells to divide the current on, I would easily go with XM-L2. Which I even do in the majority of my single cell lights. It would be fairly easy to get 6A peak, or higher depending on cell. And you would also see 5A+ for a good/long amount of time depending on the cells... Having 2 or 3 cells in parallel helps limit sag a lot!

In general you either get higher output with XM-L2, or about similar output at lower current. But I had an example that was even worse (which I mentioned to Ouchy in another thread). So if you get an XM-L with lower than average Vf, and an XM-L2 with higher than average Vf, the XM-L could be brighter, in my extreme example with a partially drained battery it was 3,5A for the XM-L vs 2,2A to the XM-L2 with a drained battery. Its not common with such a large difference though..

As for lumen vs current:

(Direct copper mount, not copper MCPCB, but its probably quite similar)

6A to XM-L gives you around 1480 lumen.

In order to get similar output on XM-L2 you only need. 4,4A. Im not 100% sure what bins was used.

2,6A to XM-L2 gives you 1000lumen. 3A To XM-L gives you 1000 lumen..

And since the XML2's voltage is higher, which gives lower current, that also means the battery voltage stays higher for longer, which helps offset the difference in when the driver drops regulation and current starts to decline with cell voltage. I think it's pretty much a wash.

Boy. Am I ever having fun now.

Yep good sum up of your experiences thanks guys, it’s good to have a spread of information. What sparked my interest in this possible crossover performance situation was when I saw those XML U2-3C NW emitters on sale recently, was wondering if in a single cell light and highly driven it might actually result in a higher total output vs the newer equivalent available XM-L2 T6-3C emitters. Even if it’s only a slight difference or possibility I was curious if it was possible that the older tech could still outperform the newer stuff.
Also I feel safer knowing the current is being spread across 3 bond wires rather than just two but that may also be less relevant in reality.

I guess this is what it comes down to for me, knowing the output bin of an emitter can make all the difference when the differences are so small. Especially when you may have older emitters that are rated at a higher output bin and therefore gain an advantage over the newer stuff with a more efficient baseline.

I may just do this test myself out of curiosity with those particular emitter bins I mentioned above and see what happens. But as you say the variation between individual emitters even within a bin is probably going to make this stuff too muddy to draw any real conclusion from anyway.

-

Ok back to the big headed light! XM-L2s all the way with this one I agree! :slight_smile:
Speaking of which the tint of the one in my light is actually pretty nice, having used it a bit more I’d be pretty confident in saying it’s a 1C tint with a nice amount of green. Makes distant vegetation pop without being too obviously tinted. Surprisingly nice actually, particularly after fixing the focus. I guess the days of getting the horrendously blue XMLs in cheap lights are gone. :slight_smile:

I was a bit confused on the issue as well, but I think I understand a lot better now. Thanks for the explanation!

This flashlight looks amazing btw. :slight_smile: