Supfire M6 - resistor mod (Update testing XP-G2s on copper in post 59-60)

Got the Supfire M6 today! :party:

My DMM said emitter current was, 2,44A - 2,4A - 2,4A measured with NCR18650B @ 4,04V (resting). That is an average of 7,28A after around 20 seconds of on-time.

Comparing those results with my other SRKs when they were stock, this is slightly higher. And both of my SRK were well driven.

The emitter with the highest current was 2,44A high, 1,27A medium, and 0,27A low. Im not able to measure strobe, would not be surprised if it was the same as high. SOS seemed to be the same as high.

Now, lets take a peak at the driver circuit.

How friendly, they even made an empty spot for a one extra resistor on R9, R13, and R17. :)

0,12R was my lowest value resistor at the moment. 2 should do the trick.

That bumped up current from 2,4A to 3,21A. Perfect!, lets add one more! J)

A total of 3 extra 0,12R resistors. (two on R17 and one on R16, see picture below)


After that I added the same resistors to the other groups limiting current to the other LEDs (marked R13 and R9 on the driver circuit). I added a total of 9 0,12R resistors. Emitter current now looks like this:

3,63A - 3,52A - 3,58A - Average of 3,57A and 10,7amps total.

The emitter with highest current (which was the same as before) now had a high of 3,63A, medium 1,93A, low 0,38A.

Notice how high medium is... That is certainly not a "cool-down-mode"...

Lets take a torture test and see if something fails.. Tail standing indoors, no breeze or anything..

Start 29C (I would assume 24, not sure why it was that high)

1 min -37C

2 min - 42C

3 min - 46C

4 min - 49C

5 min - 52C

6 min - 55C

7 min - 57C

8 min - 60C

9 min - 63C

10 min - 64C

11 min - 65C

12 min - 66C

13 min - 67C

14 min -67C

15 min -68C

Nothing died...

I don't have any output numbers. But at after 9 minutes, it did not get that much hotter. I believe I read texaspyro or someone tested it, and it lowered output or something.. Either way, what is interesting to see, is how hot it gets within the first 3-4 minutes. That is hot! I don't mind hot on high, but maybe you do. After 5 minutes it starts to get into the stupid hot territory.

Based on first impression, resistor mod seemed to be a success! I have still to try it outdoors, at night.

More to come in the future...

Very nice write up and mod.

If you ever upgrade to xml2, it would nice to see how the current changes with the same driver config. If you do such a mod, please keep the xml current numbers posted in your OP. I haven’t seen any apples to apples comparisons out there. This might be an excellent example if you do.

EDIT: Nix the above idea. I guess the difference won’t be that much at 3.5 amps.

Very nice, thanks for sharing.

Mine should arrive in about 10 hours if the postman delivers on Saturdays.

I’ll try to follow your mod, and will report the results here. :slight_smile:

Thanks for sharing!!!

I have thing to do this weekend.

Thanks. I don’t know anything about resistors or diodes, but your photos make me feel like I could do this. So you added a resistor to the empty spot and removed and added two more for each LED?
Where would I buy some of these resistors?

I saw you edited your post, but here is the answer I was writing... Others might find it useful...

I have done XM-L to XM-L2 before.. When I did my SRK with resistors, I started with stock XM-Ls just in case of "poof".. I measured with XM-Ls and with XM-L2s, on each emitter. The drop when changing to XM-L2 was close to nothing. But that was at around 3,1A.

Example of a quite recent driver I played with, the one in the Small Sun ZY-T13 I have had XM-L, XM-L2, XP-G2 on it, and emitter current was pretty much the same. But then again, that was 2 cell in series, so vf was no issue.

The main area where you could see drop, is when you start pushing beyond 3,3-3,5A and are using single cell/parallel cells. Then its harder to achieve high current to XM-L2. In this case, I don't think the drop will be that much.

I have some XP-G2s on Noctigon that has been ready for a triple for a long time. My plan is to try those in this light. Ill check emitter current, but I don't expect the current to be more than 3,3A at max with fresh cells. XP-G2s are even harder to push beyond 3A.

The resistors limit current. But these are in parallel, adding more resistors in parallel makes more current flow through.

I used these resistors for this mod. If you want to add less resistors, then you need lower value on the resistors. But I used the lowest I had at the moment. Basically, I added 3x R120 to R17(see marking on driver circuit), 3XR120 to R13(see marking on driver circuit) and 3xR120 to R9 (see marking on driver circuit). Instead of stacking 3 in height, I just added the 3 resistor onto some of the others, all of them are in parallel, so it does not matter where you put them...

I added a total of 9 resistors. Adding resistors are easy. Much easier than stacking 7135s.

Edit: Did some minor changes to OP, hopefully its easier to understand if the text above was not clear.

Thank you RaceR. Good info. Based how you got your SRK to throw, I can’t wait to see your xpg2 mod beam shots. Best of luck.

Okay. I looked at the photo closer and now I see they’ve been stacked. I think I’m definitely going to give this a whirl when my light arrives. I’ll most likely swap XM-L2s on Noctigons too.
I’ll probably have some more questions when the time comes.
EDIT: I may wait to see how your XP-G2 swap goes. I’ve been considering the same thing for a while, and wondered why nobody ever uses anything but XM-L in these triples.

nice write up!

now, if we wanted to just add one extra resistor, what ohm would we want?

That would depending on how much current you wanted.

When I added 2x R120, i got about 3,2A.

2x R120 should be the same as one R060.

If you add one R056 (the same value as stock on the driver circuit). That would probably give you around 3,3A.

so would a r030 be the same as adding three as you did?

Racer, do u know how hot it got before the mod? Or how much hotter is it now?

Thanks for this bro! Good find/work!

nice write up, I’ve just received my m6 and I’m thinking the same as you, nw or hi cri xp-g2’s would be the way I’m thinking of doing things, yes there would be a lumen drop, but the throw increase would be interesting.

It would be the equivalent of adding an R040, if there were such a thing. So adding a R030 instead would result in even more current flowing to the emitters. That is, if the cells and other components can deliver it.

EDIT: Adding a R030 would be the same as adding 4 R120’s.

thanks! not too knowledgeable with the electronic parts of this hobby. should have divided the original resistance by three, instead i divided the r060 by two, which would be dividing by 4

For those of us that are new to the resistors and mods, online calculators can help out a lot.

Racer added three .12 resistors for a result the same as one 0.04

[quote=fishmaniac] Racer, do u know how hot it got before the mod? Or how much hotter is it now? Thanks for this bro! Good find/work! [/quote]

Texaspyro did some numbers.

The stock M6 is already hotter than a hot SRK ;) I increased output with more than 43% with the resistors I used. That adds a lot of extra heat to a light that is already hot on high. 0:)

[quote=gords1001] nice write up, I've just received my m6 and I'm thinking the same as you, nw or hi cri xp-g2's would be the way I'm thinking of doing things, yes there would be a lumen drop, but the throw increase would be interesting. [/quote]


I have some XP-G2 R5 3Cs, ill see if im happy with that combo, if not, ill just swap the emitters. It might take a week before I try it. Have to play with the stock XM-Ls a little first. :)

Might even swap the driver circuit one day too, ill see how the "off" feature grows on me. UI would be so much better if strobe and SOS were hidden. Its annoying to cycle through them in order to get to off, and its a bit annoying to wait for 3 seconds in order to turn the light off too. The normal SRK is much nicer in that way. No regrets buying the light though! :) Its nicely built. I always considered it a mod host, like all other lights I buy... 0:)

The advantage with this light compared to the kings are that I can more comfortably adjust high higher due to having a medium, which is now basically a high... :p I now consider high to be turbo.. J)

I know I have a stack of xm-l 4c emitters so I’ll likely fit them, cw is far too harsh these days and that’ll get me by till I can properly mod it, it is a good quality host that’s for sure. I just lock out when I want it off, quicker than a 3 sec button press lol

lol.. I did not think of that. Thanks, Ill try it out.. :)