YUPARD Mod: 9 XML @ 3P3S with FET Driver (3S 26650) UPDATE: 4.3A per emitter! This is Insane ! (Post #37)


When I started this mod, my heart wasn't really in it. Ive been playing with KD beast drivers, and planned to put one in this this light. By the time I got to this mod, I'd realized that they only have a life span of twenty minutes, so I was kind of down.

Then I thought about the FET drivers I got from RMM. I'd never tried them, and can't say I really understood them. My mind was on one type of modding, and I'm not smart enough to learn about two things at the same time.

I wasn't sure if it would be worth my bother to try it with a 3P3S setup with nine emitters, so I talked to Richard. He assured me it would work, but I'd need to do a Zener mod. That part I still don't understand, but he assured me it was necessary. Since I'm new to all this, I just performed the Zener mod on the FET driver with blind faith.

I've been doing a lot of multi emitter lights lately, and it gets expensive swapping in XM-L2s, so I kept the original XMLs. I did reflow them onto Sinkpads though.

I did the wiring with 26AWG 9 strand silver teflon wire. I really like this stuff for multi emitter lights because of its very low profile. The bottom of this reflector is flat, so low profile is nessesary.

I stripped the stock driver for a contact board. I couldn't be bothered fiddling around with the traces, so I just drilled a hole through the middle that was the same size as the small spring on the FET driver.

Copper braid was added to the driver first and threaded through the hole. The small spring was pushed through the contact board until it was flush, then solders into place.

I kept threading the braid through the battery spring, soldered everything down, and added ground wires to the driver.

The parallel leads were bundled together and soldered to the LED +\- pads. Each set of leads runs three XMLs in series.

Notice the bit of black shrink tubing on the - set of leads. I only had one color wire, and didn't want to get confused.

In the end, this light was interesting to put together.

This is the part where I'm going to need some help. With the emitters wired 3P3S and a Zener diode in the mix, I have no idea how to calculate how much current per emitter I'm getting with 3 x 26650 in series.

I also had no idea this driver had five modes until I turned it on.

Tail readings with 3 x KingKong 26650

100% - 10.09A

- 4.36A

- 1.78A

- 0.34A

- 0.10A

I didn't know what to expect when I first turned it on. But it's real bright and I'm real happy. Plus I won't have to pull out a dead KD driver after twenty minutes.

It was a long day, so I haven't had time to braid the tailspring, and the reflector is sitting up on a couple of the centering discs. I'll fiddle with that stuff tomorrow.

And to top off the bottom, my signature clear bootcap.

Happy Modding.

I just had the light outside and it’s awesome. I really didn’t think it was going to be so bright.
I wish someone could help me confirm what kind of current I’m getting per emitter.


Unless I am missing something you are looking at 30A divided between the 9 emitters. So 3,3A to each emitter.

Same brightness as my 9xT6 light now.. Which is stupid bright! :D This is why many like these FET mods. ;)

Thanks RaceR86.
Those were the numbers I came up with, but they seemed too good to be true. Should there be some allowance in the equation for the Zener diode?

Now to figure out how to run one with a light that has an odd number of emitters. (5 or 7)

[quote=Ouchyfoot] Should there be some allowance in the equation for the Zener diode? [/quote]

Sorry, I don't understand the question.

You have a linear driver. Input amps is the same as output amps.

This is just like a single cell light running a FET driver. Only that you have 3 batteries in series, and therefore also need to have 3 emitters in series.

The Zener is basically there in order to fix the input voltage to the MCU, because the MCU is not built for 12V input, so the Zener takes care of that bit, as far as I know. (Im not much into the technicalities of the zener mod, I just know it works.)

I don't think many have done these mods with 12v input yet. Only heard RMM mention it. Is it the same zener diode as used on the regular (2 cell in series) zener mods?

If cells are in parallel, you can just wire all emitters in parallel. Otherwise, not so easy..

Yes. Just the standard Zener diode and R200 resistor.

Okay. Here’s my question, and it’s not a joke. I’m dead serious.
Can one of these drivers be modded to run 6 cells in series? Yes really. 6 cells in series with 12 emitters.

Ill leave that question to others.

But Im planning on running 6cells (2s3p) with 12 emitters (2s6p) from Zener modded FET driver.

Are we both looking to mod the same light?

I have ordered this:


That’s the one I’ve been planning on modding ever since you showed it to me. Looks like were building the same light. Hope you don’t mind. Are you going to keep the XM-Ls or go XM-L2? Lots of investment for twelve new emitters.

Cool! Go for it!

I have not decided between XM-L2s or XP-G2s.

The build will probably have to wait some time though. So you might beat me too it.

Dx has the xml2 version for a bit more.


I could probably use some advice on the way. I always find unexpected hurdles.
I’m ordering it now. I’ve had it bookmarked for ages and look at it every day. It was only a matter of time. I was originally trying to decide if I wanted the Hyperboost, but it has no modes. This light will get hot on high.

whoaa… nice mod, I was about to give up on my 9T6… I guess this will help me kick start my project again… thanks,
BTW is this FET driver was the one meant for building Mt-G2 light?

Yes. The same one.

I don’t know if I want to trust DX. It does say XM-L2, but they still have the stock XML pictures. I mean if they’re XM-L2 great.
Now I don’t know what to do.

I wonder if I can run that FET driver with 9 XP-G2 LEDs on noctigon? :bigsmile:

Nice! What firmware did you use on that FET driver?

man 10A whoah! Gotta be getting mighty warm on high

Excellent job!

Will be pushing ALOT of amps but if the XP-G2 can handle it…will make one HECK of a thrower !

I got the FET driver from RMM.