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

how does that compare to a SRK host?

Driver chip is AMC7136. its Current sense feedback voltage is 50mV

Your stock driver setting: 3x 0.056 ohms = 0.018 ohms

Stock drive current = 50mV / 0.018 = 2777 mA

After 2x0.120 ohm resistor added, 0.018 & 0.060 = 0.013 ohm

now drive current will be 50/0.013 = 3846 mA

The hosts handle the same amount of heat and stabilize at around the same temp/light level. The M6 driver compartment heats a lot fast than the SRK (maybe because the black body radiates heat back into it better).

Nice mod. Thanks for sharing!

Here's my quick calculations of your mod and a hypothetical mod with 1..5 pieces of 0.1 Ohm resistors:

RaceR86 mod Planned mod
Stock resistor 1 0.056 Ohm 0.056 Ohm
Stock resistor 2 0.056 Ohm 0.056 Ohm
Stock resistor 3 0.056 Ohm 0.056 Ohm
Extra resistor 1 0.120 Ohm 0.100 Ohm
Extra resistor 2 0.120 Ohm 0.100 Ohm
Extra resistor 3 0.120 Ohm 0.100 Ohm
Extra resistor 4 0.100 Ohm
Extra resistor 5 0.100 Ohm
Resistance
Stock 0.01867 Ohm 0.01867 Ohm
w. 1 extra resistor 0.01615 Ohm 0.01573 Ohm
w. 2 extra resistors 0.01424 Ohm 0.01359 Ohm
w. 3 extra resistors 0.01273 Ohm 0.01197 Ohm
w. 4 extra resistors Ohm 0.01069 Ohm
w. 5 extra resistors Ohm 0.00966 Ohm
Feedback voltage (mV) 45.5 Calculated back from the measured 2.4A emitter current - takes driver losses etc. into account..
Emitter current
Stock 2.44 A / emitter 2.44 A / emitter
w. 1 extra resistor 2.82 A / emitter 2.89 A / emitter
w. 2 extra resistors 3.20 A / emitter 3.35 A / emitter
w. 3 extra resistors 3.58 A / emitter 3.80 A / emitter
w. 4 extra resistors A / emitter 4.26 A / emitter
w. 5 extra resistors A / emitter 4.71 A / emitter

That’s pretty awesome.

Thanks for the calculations!

Am I right that the upper limit to this mod is, in effect, direct drive? After all I believe that the cells are in parallel as are the 3 emitters. This is good as there is less danger in wildly over driving the emitter.
The TR-3T6 resistor mod had 2 or 3 cells in series. If I had this light, I wouldn’t hesitate to do this mod.

Nice calculations _the_.

Should be good guidelines. :)

[quote=dchomak] Am I right that the upper limit to this mod is, in effect, direct drive? After all I believe that the cells are in parallel as are the 3 emitters. This is good as there is less danger in wildly over driving the emitter. The TR-3T6 resistor mod had 2 or 3 cells in series. If I had this light, I wouldn't hesitate to do this mod. [/quote]

Most likely yes. We can not know how far the resistor mod will work until someone tries it though. Might be limits. But as can be seen, medium and low becomes higher too. About 3,6A to each emitter is already at the stupid amount of heat for this light IMO. It will be very useful in the winter though. Not only does it function as a light, but it will be a great hand warmer too! :)

4 cells in parallel will be able to kill 3 XM-L mounted on aluminium in DD, so DD is not a good idea on stock emitters. Put in XM-L2s mounted on copper and you should be able to output the amount of current you desire, if the driver will do that. But there is really not much point in going beyond the 3,5-3,6A range IMO. Not only due to vf of XM-L2s and the less great medium and low, but mainly due to heat.

I’m loving this thread. I’ve been seeing resistor modding in the forums a lot lately, but most of the chatter was between modders with electronics backgrounds. This thread is truly helping me understand what is going on. The before and after pictures by RaceR86 gave me immediate focus of the what and how, and each additional post has helped me with the why. Now I’m looking at all my lights a little differently. I can’t wait to get started.

One of the original emitters failed during the experiment (not sure why), so I don't have directly comparable results, but here we go:

2 x 0.1 ohm resistors did boost the emitter current to about 3.3-3.4A (with XM-L2 3C on Noctigon), quite well in line with my calculations.

Output jumped up to about 3100 lm (OTF, after 30s)

3 x 0.1 ohm resistors gave another 100 lm, up to about 3200 lm of nice neutral white light.

Light
Approximate min lumens
Approximate max lumens
SupFire M6-T6X3 XM-L2 3C (3x0.1ohm mod) 390 3,196
SupFire M6-T6X3 XM-L2 3C (2x0.1ohm mod) 381 3,102
BTU Shocker NW XM-L2 Mod 52 3,079
BTU Shocker CW 52 2,820
Solarstorm Warrior XM-L2 T6 1A 94 2,397
Skyray King CW 235 2,298
Trustfire TR-J12 338 2,195
SupFire M6-T6X3 301 2,190
BTU Shocker NW 47 2,181
Skyray King NW 230 2,096
Solarstorm Warrior XM-L U2 1A 85 2,077
APEX 5T6 NW 150 1,941
Blackshadow Darth NW 169 1,532

Ps. Throw is now about 49kcd (440m)

Edit: Fresh cells -> 3309lm (OTF, after 30s)

_the_ that is sweet, and your calculations seemed good too.

Based on the resistor values, and amps, we seemed to get very similar results, so that is always nice to see. :)

Are you one of the people who have ordered AR coated lens from CNQ? Would be nice to see your lumen comparison on your modded light with AR lens vs stock.

(I know many others have those lenses coming, and some will probably share, but the more numbers we get, the better)

Edit: did you measure current with 3 x 0.1 ohm resistors?

Not yet.. But I think I need to order some.. ;)

Didn't have time for unsoldering the emitter leads again for measurements. Sorry. Might do this later (I know, I should buy a clamp meter)

I have a feeling you will order at least one pretty soon. Im still waiting, I want to see some numbers before I pull the trigger.

If you find the time, this day or another, please check emitter current with 3 x 0.1 resistors. Considering that you only saw a 94 lumen gain going from 2x 0.1 to 3x 0.1. Im wondering if you are not seeing much of that calculated output (3,8A) due to vf and such of the copper mounted XM-L2s.

Some may be familiar with my other SRKs (SRK/UV-S5), both modded. A little comparison here.

I tested both of those vs my current Supfire M6 (not supbeam as wrote on one picture). Mouse-overs below.

Camera settings:

1,6s, f5, iso400, 17mm (aps-c), WB was 5000K on first comparison, and 5200K on the second.

What other members have noted, or showed before. The M6 have less flood, and a more defined hotspot with slightly more throw. Otherwise, not a huge difference compared to my other modded king. In real life, there is no doubt M6 appears brighter due to the more harsh light. Output difference is not that much though. Due to tint,CRI and such, id take the SRK easily. Much nicer in real life. But its impressive to see the output of the M6 with stock emitters (and modded driver circuit).

When it comes to throw, I compared it to my SRK with de-domed emitters and a much lower current. The treeline in the distance are 120 meters away. The de-domed SRK wins fairly easily, not a surprise really. Due to not having that much bright spill, I would say its a better thrower in real life than in the picture. Lots of bright spill and flood kinda limits the ability to see things in a distance. The M6 outputs a lot more light though(!), and still have decent throw despite running close to 3,6A to XM-Ls on aluminium. And when XM-Ls are on aluminium, gain above 3A is not that much.

it seems there is some mistake on 2nd picture RaceR,it supbeam instead of supfire :bigsmile:

Yupp, you are correct. And if you read the 2nd line I also said so. You even quoted me on it.

Good guess. Ordered some. :)

I'm not totally sure about this (had some problems measuring), but I got readings of 3.5-3.7A. I think you are correct about the vf and such.

Ps. Nice beamshots!

There is a formula that one can use to calculate current if the voltage drop across the resistors is known. It can be obtained by putting the DMM leads on each side of one of the resisters. The formula is:

Vdo/[1/{(1/R1)(1/R3)…+(1/Rn)}]

Please excuse me if I’m using the wrong types of brackets above. Just trying to make the formula easier to follow. I don’t know if Vdo (voltage drop out) is the correct term either. I don’t have any formal electronics training.

amazing results _the_

so the m6 is actually brighter than both of your BTUs? how fast does it heat up?? thats crazy

Thanks!

Yes, more lumens than in either of my BTUs. Much less throw though. ;)

Heats up pretty fast, but I haven't tested longer than 1min bursts yet..

BTW / OT: These resistor mods are addictive.. I continued by adding 2 x 0.1 Ohm to my de-domed XP-G2 TN31 -> 440kcd

how much more output would you expect from a AR lens? just 6% more light, and it will be over 3500 lumens