COURUI DO1 'Big Head' (Black/GRAY NOW AVAILABLE) $29.99 @ Gearbest ( use coupon: gbcourui) A long-throw modder's light!

This is what I want to prevent that’s why I put kapton tape all over the bottom part of my reflector.

I hope you have the same luck as rexdog said. Well if its the driver that got busted then I think you can use it as contact points and use (piggyback as wight said) a Nanjg 105c as your driver. With the 105c, you can add as many AMC7135s as the space will allow and drive your LED the way you want it. That’s what I did (use Nanjg 105c) with my TangsFire HD-2010 when I fried my driver too (no not piggyback as its physically impossible to do with the HD-2010). :slight_smile:

I have an extra factory driver I could sell. Another alternative is using a 7135 based driver with TomEs version of the MomStar UI. I have been using a 6000ma board with that UI with good results. It wont deliver quite 6A with only a single XML, but I still like it better than the factory board.

Thanks for the replies chaps.

Unfortunately I did fry the board. There was a large curl of smoke when it died, and what I think is a mosfet has burnt out and distorted.
I suppose the good part is that the led is ok...

@ vestureofblood, I would certainly be interested in buying your spare, I prefer a simple UI (and simple wiring too) how much would it be with postage to the UK? (standard air mail would be fine, I'm in no hurry).
Feel free to PM me if you'd prefer.

So is there an actual difference between the grey and black versions? I’m going to order one…but I prefer the looks of the black one. But if the grey is a better light, then I’ll get it instead…

Only difference reported has been with the mcpcb size & centering ring that I know of, but that was earlier in the piece.
Body & drivers seem to be consistent. I have both.

As recommended by tatasal, I dedomed my beefed up (resistor mod and thicker wires) Courui D01 which was already doing 117,733 cd. Here it is beside my modified K40:

The dedomed D01 at the left has a wider hot spot than the dedomed K40 at the right. However, its hot spot is more intense than that of my K40.

A reading taken at 11 meters gave 1928 lux. This can be computed to 233,288 cd or 966 meters throw. My modified K40 with its 6.1 Amps LED current, 18 AWG lead wires and all the works only gives me 182,468 cd and is clearly outmatched by my modified D01 with only 4.4 Amps LED current. :open_mouth:

There should be something not right in my modding methods of my K40 and this has kept me awake the whole night last night. :weary:

No wonder other modders got 300 kcd to 400 kcd with their K40s - and I always thought that it was just my lux meter reading differently. I think I’m gonna retake my K40 modding 101 to see what I did wrong. :frowning:

Any advise from the BLF experts? :bigsmile:

Has anyone got a foggy reflector? Mine is foggy, matte, :frowning: It can be seen better when the light is turned on.

Nightbird - good to see your COURUI came out so well. For the K40, oh boy, could be several things. First suspect would be the LED itself - maybe a poor reflow to the MCPCB, maybe just a poor performing LED. Definitely check out the reflector and lens carefully, but if that looks ok, the LED would be my first suspect - sorry, can be pricey to sub it out though, just to verify. I'd assume you have it focused, and the LED situated without a blocking centering/alignment piece, etc. From the beam pic, it looks well focused.

Thanks Tom E! I think I found the problem.

I had a feeling that the problem is with the K40 reflector so I tried to compare the performance of the K40 and the D01’s reflectors using the D01 body (and emitter). Here’s the set-up:

First I used the D01 reflector set-up like above and took the readings at 6 meters. The highest reading I got after all focus adjustments was 6030 lux or 217,080 cd.

Next, I used the K40 reflector set-up like above and repeated the whole process at 6 meters. The highest reading I got after all focus adjustments was only 3180 lux or 114,480 cd. :open_mouth:

So my I guess my theory is true. The K40 reflector is NOT as good as the cheap D01 reflector. My K40 is an old model originally with an XM-L.

Here’s a closer look at the two reflectors:

The K40 reflector at the left is deeper than the D01 reflector at the right and it is just a bit narrower so all other things equal, it should perform better if not at par with the D01.

Here are the front ends of the two reflectors. What I noticed is that the K40 reflector is dark where the D01 reflector is bright colored and this could be the culprit. Much of the light from the LED could just be absorbed instead of reflected forward in one direction. Also, not obvious is that the K40 reflector is like a cross between an SMO and an OP reflector while the D01 reflector is 100% SMO.

For comparison purposes, the Vostro BK-FA01 reflector is also bright colered like the D01 reflector and this could be the reason of the Vostro’s and the D01’s more than 200 kcd compared to my K40’s 182 kcd max.

To further confirm that the K40 LED is not the problem, I reassembled the K40 and took the readings at 6 meters, and I got 4650 lux or 167,400 cd. Compared to the 3180 lux using the D01 body (and LED), the 6.1 amp current of the K40 has indeed driven its emitter (an XM-L2 T6 1A) farther than the 4.4 amp current of the D01 (XM-L2 also).

Are the reflectors of your K40s similar to mine? :quest:

Yes I have a foggy reflector, seems standard on the gearbest couruis because I have a second one with exact same foggyness…
I tried to wash and or polish it away but all I got was a foggy and scratchy reflector…

Can't check mine now (@work), but I know my K40 performs well - got mine in the group buy. That dark look is bazaar Surprised.... Don't think I ever seen anything like that. The depth of the reflector explains the tighter beam pattern - a tighter beam pattern doesn't always mean better throw, I've seen several times, as is in this case.

But with the almost similar specs of the two reflectors, their outputs using the same LED source should have been close. I agree that deeper doesn’t always mean better. The dedomed Vostro gives 223 kcd and a very tight hot spot at measurements taken at 11 meters. The dedomed D01 on the other hand gives 233 kcd and a wide hot spot.

My guess (if its not as is from the factory) is that the dark reflector of my K40 is a result of tarnishing. I’m working in a Geothermal Field and metal parts of our equipment and tools here like brass, copper, aluminum and stainless steel tarnish easily. I think its because of the H2S in some parts of the field. My K40 is the most opened flashlight I have because I learned to mod using my K40 and many times during my learning phase I continue modding during breaks at the office. :bigsmile: From now on I think I should limit modding at home.

Pure copper pill for this Courui available: ( by NikolaS )

Thanks tatasal for sharing my offer ………


Guys, take a look at this: !!!

Courui "Even Bigger Head" D01 Projector: 113mm Lens , Luminus SBT-70 @ 13.5Amps *Build Stage* (by LinusHofman)

Perhaps going to be the ultimate `Big Head`….(this thread, and that of NikolaS, now added in OP)

I am sorry if I missed this mentioned,

I want to know if there is enough room to add a “blank” PCB between the batteries and the head (converting from 3P to 3S).

2 of the cells will need to be insulated from the head by the PCB. I am wondering if there is room?


This has been done before:

I think CK is also working on this

New modding thread on the Courui: my Courui D01 project: COMPLETE (by Caleb-v)
Added to OP.

I ‘shamelessly’ copied FmC’s mod last night and got 3010 lux at 11 meters which can be computed to 362,210 cd or 1207 meters throw. :open_mouth:

Also got 3.62 Amps reading at the tail cap with 4.13 volt batteries. :wink:

This is now my strongest thrower so far and I’m really loving this light. :beer: