MOD: C12 + MT-G2 = Lotsa Fun!

Host: Ultrafire C12
Emitter: MT-G2 P0 5000K on 20mm Noctigon copper MCPCB
Driver: Qlite 105c modified for higher voltage (zener diode mod) with 4 extra 380mA 7135s, for a total of 12 (4.56 amps estimated)
Cells: 2x Efest 18350 V2 or 2x NCR18650PD (extended)
Optic: SMO with enlarged emitter hole
Tailcap Measurements:
Moonlight: 0.01A (may actually be less)
Low: 0.10A
Medium: 1.25A
High: 4.49A

What can I say? I’ve been doing WAY too much reading on this forum! :slight_smile: This build was inspired and facilitated by the great work of many of the great contributors on this forum (special thanks to old-lumens, comfychair, Tom E, DBCstm, ImA4Wheelr, and many others). To think that it was just two months ago that I received my first budget light and began frequenting this forum is astonishing. This is my first completed build, and I felt like sharing some of my experiences here.

Although I have reasonable amount of experience with the finer things in life (mill, lathe, drill press, etc.) and used to have access to them, my current tools and environment are truly “budget”; which fits perfectly into the spirit of this forum. I am currently a law student living in a small apartment with my small family and as such my nice metal workbench has transformed into a study desk, my lathe is now a Harbor Freight rotary tool, and my beefy bench vise has turned into a small suction-cup-mounted device. Juggling family, school, and work doesn’t leave much time for hobbies; such as flashlight building, so my builds are always done at night (when patience has long disappeared) and take a long time to complete. That said, I have enjoyed making these little monsters come to life.

Now on to the build:

This light started life as an XM-L2 C12 with a 3 mode driver which I subsequently swapped for a 105C with a few extra 7135 stacked on it for good measure.

It was pretty bright and I was satisfied with it until I started reading a lot about this… :slight_smile:

Reading about comfychair’s C8 mod drove me over the edge… before I knew what happened I was on intl-outdoors ordering one of the big beasts. I also had some reading to do about how to convert the 105c so that it can survive 6+ volts. I figured that the C12 host would be a good candidate because of the large pill and sufficient space (just barely!) to fit 2x18350 cells.

In time, the emitter arrived. Time to get to work!

Hmmm…. it doesn’t fit in the hole (yet!)

I used a rotary tool with a diamond bit to carefully enlarge the emitter hole. It isn’t perfectly round but it is good enough.

Out with the old, in with the new.

Emitter mounted, wires soldered.

Qlite (Nanjg 105c) zener modded, running 12 x 380mA 7135s - thermal grease added to pill threads

Mounted in the pill (with lots of nasty flux residue still on the board!) 4th star chosen for 4-mode (moon-2–25–100%)

It’s alive!

This light has the option of either being run in shorty mode (2x18350) or extended mode for more runtime (2x18650)

Here are the cells: Efest V2 IMR 800mah 18350 and Panasonic NCR18650PD

Copper braided tailcap spring with bronze nub removed to gain extra clearance for the 2x18350s

How does it perform? Very well! To the naked eye, the beam is very similar to my SRK. The hotspot isn’t quite as focused, but it is close. The spill is also a bit wider than the SRK. The beam and tint make this light very nice to use inside the house. The four modes make this light more usable than the SRK for close-up work.

I haven’t done any conclusive runtime tests yet, but on full power the 18350s start to dim noticeably after around ten minutes of use. The body heats up fast on full power, but I left it there for five minutes and although it was almost too hot to touch, nothing melted. It can be run on the second to highest power until the batteries run out without getting uncomfortably hot, which still provides quite a bit of light.

Here are a few poor beamshots (I will try and take some better ones in the next few days)
This wall is not white, but more of a cream color.

SRK, MT-G2 C12 at around 4.5A, XM-L2 T6-3A at around 3.8A

MT-G2 left, SRK right

XinTD XM-L2 left, MT-G2 right

Daylight fixed WB, manual shutter, ISO, and aperture. These shots aren’t very good, I’m going to set up the tripod and take some better ones sometime this week. These are not very good comparison shots because I was handholding everything and in a hurry.


MT-G2 C12

XM-L2 3A XinTD V4

Again, I have to thank everyone on this forum for all of their contributions which made this build possible.

I will update this post with tailcap readings (only accurate up to ~2 amps with my DMM), runtimes, and better beam shots as time allows.

Very Nice! Good to see you stepping into the modding arena. It's addictive.

Congrats on a very cool build.

i really must own/mod a c8 to mtg2… they just look awesome

Nice work RMM. Now I want one.

Well done , sir .

Thanks for sharing .

Very nice and well thought out mod, you have made yourself a awesome performing flashlight :-) . I will not confess what my first mods were, but they were way more simple than this one, well done!

Well done RMM. Those MTG-2’s can become addictive. love your mod and even better it works. Whats next?

Since you asked, I’ve got a few in the works (but nothing too original):

  1. 3D Maglite XM-L swap (to run on alkalines, will be a Christmas present).
  2. ZY-T08 de-domed XM-L2 on copper, maximum amps possible (will be my first de-domed thrower). Not sure yet what driver I will end up with, I think I’m going to try and turn up the stock driver first on this one. Will be using Samsung 20R batteries for this one.
  3. Trustfire 3T6 with DRY driver swap.

None of these are as cool as what you guys do, but I am having fun and hope to continue to increase my skills.

I still have a long ways to go when it comes to soldering, but I finally am feeling a little more competent. Before starting this flashlight hobby I had lots of experience welding with my various jobs (Mig, Tig, etc.) but no real experience soldering. My first few attempts were pretty frustrating until I did some reading; I found out that you don’t solder like you weld. I bought one of the Yihua stations from Hobbyking which is much nicer than the $3 Harbor Freight special I was using. I have also been watching a lot of helpful YouTube videos on soldering. Most importantly, I have been practicing and getting some experience. I still have a long way to go; some of the stuff I see soldered on here looks like a work of art. Right now I’m at the “it’s shiny, strong, and conductive” stage; better aesthetics will come with time.

I was really glad when I put it all together that the zener/resistor modded driver worked correctly. I checked everything as I was working, both visually and with the DMM, but I’ve worked on enough projects to know that if something can go wrong, it WILL go wrong with me! :wink:

This is really cool, well done! Can’t wait to get my Mt-g2s and have a play. Out of curiosity the c12 is identical to the c8 apart from the extra heatsink fins right?

Yes, they are very similar, but vary a lot from manufacturer to manufacturer, so it is hard to make a blanket statement. Along with the extra external heatsink fins, the pill in my C12 is larger and has more contact area than the pill from my XinTD V4.

Excellent work, RMM! One of these days I will have a go with an MT-G2. :)

I have been trying to modd my c-12 and have failed miserabley this week I still haven't had a chance to find out why but I was. Changing the driver to a 8 chipped 380 mAH 7135's on and a XML2T5 on a 16mm copper star with no luck anyhow as soon as things slow down ill take a looksie but kudus on a MT-G2 I love the MT-G2 emitters huge hot spot.

That's a great build.

Where do you get a C12 extension tube?

From eBay. I couldn’t find one anywhere else that fit right. It was more than I wanted to spend, but it was the only option I could find.
$8 C8 Extension Tube

Added tailcap measurements to OP.

Really nice job RMM! Hhmm - like that C8 extension tube, for $8 shipped from US, not that bad really - it's an unusual item. I didn't know they were available.

Great mod RMM! One of these days I'll do an MT-G2 build!


Thanks, I just saw your post. A little pricey considering Banggood just had a whole C8 for $8.88, but what can you do?

Great mod! They way you do this is quite clean and thorough.