# Mag XM-L Mod



## LilKevin715 (Apr 29, 2011)

Here is a Mag XM-L mod that was pretty straight-forward. The main goal of the project was bang for the buck. I hope this mini-guide will be helpful to others as I myself have learned a lot from others here on CPF; just my way of contributing back to the forums.

Specs:
Mag 2D Gray (Incan version)
Cree XM-L T6 1D tint on 14mm round board
H22A Flattop Bare Heatsink
Shiningbeam 2.8A 3-Mode PWM Linear Regulator Driver (8 X AMC7135)
20 AWG Silver coated Teflon jacket wire
3 x C Accupower 4500mAh NiMH LSD Batteries
52.1mm Hardcoat Acrylic Lens



 

 



The first pic shows 20 gauge Teflon wire soldered to the emitter board. I then attached the emitter board to the heatsink with Arctic Alumina thermal epoxy. The emitter wires were then bent into shape for preparation for the driver as seen in the next set of pictures.



 

 



The battery wires were then soldered to the driver as well as selecting the desired mode (3-mode) by bridging the correct star to the outer ground connection. The emitter wires were then soldered to the driver. I then attached an anodized Akasa BGA ram heatsink to the LED side of the driver with Fujik thermal glue. The main purpose of the BGA heatsink is to prevent any possible shorting of the driver on the main heatsink.



 

 



The stock switch was then modified (cam cut off) and the battery wires from the driver were soldered to the switch. The switch assembly was then placed back inside the battery tube and the snap ring was reinstalled. Ceramique thermal paste was then used on the inside of the battery tube and on the heatsink accordingly.



 

 



The heatsink was then pushed into the battery tube and any excess thermal paste cleaned off. Also pictured is the modified stock reflector with the focusing cam cut off. The best focus was obtained when the top of the emitter pedestal base was at the same level as the bottom of the reflector lip.



 



The use of 3 C cells in a 2-D host requires a battery sleeve (1 inch ID/1.25”OD PVC pipe). The tailcap spring was cut down and the anodizing was removed from the inside of the tailcap with Drano Max Gel. 

Beamshots will follow shortly…


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## LilKevin715 (Apr 29, 2011)

Beamshots have been uploaded. Not the best quality but good enough to get a general idea of the beam profile. Pictures are slightly underexposed to show better detail of the beam. Shots were taken about 0.5m away from the wall.

Low/Medium/High


 

 



XM-L Mag vs. SST-50 (4500k) deep SMO Mag, both use same driver.


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## RepProdigious (Apr 29, 2011)

Nice clean build but wont the thick wires next to the led destroy your beam quality?


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## LilKevin715 (Apr 29, 2011)

Before soldering the wires to the emitter I did check the height of the wire & teflon insulation. If light from the emitter was emitted at a 180 degree angle then yes it would probably affect the beam profile. However the XM-L has a light emitting angle of 125 degrees. 

Here is a picture at close to eye level




I did press down on the wire as hard as I could with tweezers while soldering the wires in place. You can see some indentations from the tip of the tweezers on the wire insulation in the pics.


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## StefanFS (Apr 29, 2011)

That's how I would do it. 
You could even add a generous amount of glow powder/epoxy mix around the emitter with no ill effects to the beam. That's a nice effect.


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## Essexman (Apr 30, 2011)

I'm building a maglite just like that, thanks for the pics and text.

When running on full power what current draw are you seeing at the tailcap?


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## ljw2k (Apr 30, 2011)

Looks a nice clean simple build mate and as Essexman i am also waiting for parts for the same build only using a different driver as the batteries i have bought are UN protected D Cell from DX and the driver i am using has built in safty features.

http://www.lck-led.com/p501/Constan...3-Modes,5.5-12v,3.0A,P7,MCE/product_info.html


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## LilKevin715 (May 1, 2011)

> When running on full power what current draw are you seeing at the tailcap?


Tailcap current draw measurements are 0.13/0.86/2.79 amps. If I assume 25% optical losses then OTF lumens are in the neighborhood of 42/252/655 (according to Cree data sheet).


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## steviedezie (May 16, 2011)

Where can i find the heatsinks for a maglite???


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## LilKevin715 (May 19, 2011)

steviedezie said:


> Where can i find the heatsinks for a maglite???


 If you re-read the first post carefully you will find your answer... (and a simple CPF search).


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## don2k9 (Jun 6, 2011)

This mag mod is so beautifully done. I did my mod on my 4D with a P7 on the same heatsink from H22A two years ago. Powered by 3x18650, the thing is the heat generated from the driver is so out of control it will shut itself down in 15 minutes during the summer days but works fine in the winter. 
I've quit myself from flashlight for nearly 2 years, even lost my old account here in CPF. I decide to try something new on my Mags this time, since there are so many new things out there on the market.


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## freeloader700 (Mar 5, 2012)

Very nice...I am in the middle of this same build. Excited to see how it turns out


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## LivingDaylight (Mar 6, 2012)

Is this the driver you used?

http://www.shiningbeam.com/servlet/the-132/3-dsh-Mode-Regulated-Circuit-Board/Detail

I ordered that for a mod I have planned. I also ordered an XM-L on a 16mm board, so I might have to cut down the reflector a little more.

Thanks for this timely post!


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## Justin Case (Mar 6, 2012)

IMO, using 3xC NiMH might not provide enough Vbatt to reach full regulation when using a 2.8A 7135 driver.

At that drive current, an XM-L Vf may be about 3.3V based on the datasheet. Add 0.12V for the 7135 overhead. Thus, you need at least 3.42V to reach/stay in regulation. If the Mag mod has 0.1 ohms of parasitic resistance, that is another 0.28V, for a total of about 3.7V. Unfortunately, based on Silverfox's NiMH shootout data, Accupower C NiMH cells will sag below 1.25V at 3A draw within about 10 min of run time. Most of the Accupower C cell's voltage plateau looks to be at around 1.2V. Out of about 5Ah/2.8A = 1.8hrs battery capacity, only 10 min of it is in full regulation. The rest of it is out of regulation.

If the actual Vf is lower, say 3.2V, then that helps. If the Accupower C NiMH cells can hold a higher voltage (let's say that the plateau is 1.25V at 3A draw), that helps. If your Mag has only 0.05 ohms parasitic resistance, that helps. I wouldn't count on better performance from the Accupowers. But a lower Vf certainly can happen. And you can implement various resistance fixes for the Mag. Then, you need about 3.2V + 0.12V + 0.14V = 3.46V to reach/stay in regulation, while Vbatt could be at least 3.6V.

it all depends on what you have.


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## moderator007 (Mar 6, 2012)

Justin Case, I agree with your statement above. Do you know if anyone has actually tested the amc7135 at 2.8A and a XML with 3 D Nimh's in series? It would be interesting to see the results. I know we can mathematically figure if it will stay in regulation or guess on when it falls out of regulation. But I have never seen the actual numbers. And I do realize there would be alot of variables but at least we would have some guide to go by.


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## Justin Case (Mar 6, 2012)

I have a triple XP-E powered by 6x7135 (2.1A) and it requires about 3.66V to reach full regulation when powered from my bench supply. There is probably some parasitic resistance in making contact to the center spring and ground trace of the driver. The connecting wires themselves are 18 gauge stranded copper, 1 foot long. I measure about 3.2V for Vf at 2.1A nominal drive. So the overhead is already about 0.46V, which seems like a lot since I'm simply using a bench supply to power the triple drop-in. Of course, I didn't put a lot of effort into optimizing the test setup.

Edit: The XP-E datasheet says that Vf is 3.4V at 700mA drive. So my sample is 0.2V under that.


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## moderator007 (Mar 6, 2012)

I wonder if a burn in of a XML would help lower its forward voltage Like the sst-90. Could help stay in regulation longer if it worked.


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## Techjunkie (Mar 6, 2012)

Justin Case said:


> I have a triple XP-E powered by 6x7135 (2.1A) and it requires about 3.66V to reach full regulation when powered from my bench supply. There is probably some parasitic resistance in making contact to the center spring and ground trace of the driver. The connecting wires themselves are 18 gauge stranded copper, 1 foot long. I measure about 3.2V for Vf at 2.1A nominal drive. So the overhead is already about 0.46V, which seems like a lot since I'm simply using a bench supply to power the triple drop-in. Of course, I didn't put a lot of effort into optimizing the test setup.
> 
> Edit: The XP-E datasheet says that Vf is 3.4V at 700mA drive. So my sample is 0.2V under that.



As long as the light is a side-switch light, where Batt+ is interrupted by the switch, like in a Maglite, you can escape the switch resistance to the LED by hardwiring the Batt+ contact at the bottom of the switch directly to the LED+. LED- still has to flow through the regulator to get to ground (Batt-), and can't do that while the regulator is powered-off. See here.





moderator007 said:


> I wonder if a burn in of a XML would help lower its forward voltage Like the sst-90. Could help stay in regulation longer if it worked.



Hey, I know that thread


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## moderator007 (Mar 6, 2012)

Techjunkie said:


> Hey, I know that thread


Well, you should:twothumbs. 
I am pretty sure I have seen you build some 4 or 5 amps mags with a XML. You didn't happen to check the Vf after a few cycles did you.


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## Justin Case (Mar 6, 2012)

Techjunkie said:


> As long as the light is a side-switch light, where Batt+ is interrupted by the switch, like in a Maglite, you can escape the switch resistance to the LED by hardwiring the Batt+ contact at the bottom of the switch directly to the LED+. LED- still has to flow through the regulator to get to ground (Batt-), and can't do that while the regulator is powered-off. See here.



It's a P60 triple in a SureFire 6P. No side switch. The Maglite has lots of resistance fixes that can be implemented.


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## LilKevin715 (Mar 7, 2012)

Justin and moderator007:

Please see my Vf vs Temp thread I created a while back(now updated), it should answer some of your questions.

I don't know if a XM-L could or even would benefit that much from a burn-in compared to a SST-50/90. Its one thing if the Vf was in the 3.7v+ range, but the Vf of a XM-L is pretty low already.


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## Techjunkie (Mar 7, 2012)

moderator007 said:


> Well, you should:twothumbs.
> I am pretty sure I have seen you build some 4 or 5 amps mags with a XML. You didn't happen to check the Vf after a few cycles did you.



Not that I recall, no. XML are so low Vf to begin with, I've never had desire or need to pay as much attention to that detail for them as with the SST emitters. If anything, I've had the opposite problem with XML, having to add resistance to keep regulators from overheating. Generally speaking, all LED have lower Vf when they're hot than when cool, but burn-in of CREE LEDs (lower Vf even at cool temps after they've been broken in), is not nearly as drastic as with other LEDs (possibly even non-existent).


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## Justin Case (Mar 7, 2012)

LilKevin715 said:


> Justin and moderator007:
> 
> Please see my Vf vs Temp thread I created a while back(now updated), it should answer some of your questions.
> 
> I don't know if a XM-L could or even would benefit that much from a burn-in compared to a SST-50/90. Its one thing if the Vf was in the 3.7v+ range, but the Vf of a XM-L is pretty low already.



It is well-known that LEDs are negative temperature coefficient devices. The coefficient is given in the Cree datasheets. For an XM-L, it is -3mV/C. However, I don't think that the question was Vf vs temp. It is Vf vs If, with If at the upper end such as at 3A (or even more).


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## LilKevin715 (Mar 8, 2012)

Perhaps I should have been more clear with the linked thread. It was mentioned in reguards to regulated runtime. 

There is no doubt mags do have resistance, but 0.1 ohms seems a bit much in a setup such as mine. CKOD measured the resistance of a stock tailspring (#1 and biggest offender) and obtained a value of 0.027 ohms. That seems more realistic as my regulated runtime was well over a hour. A 3 X C or D nimh setup with a AMC7135 driver is definately doable and fesible for a XM-L. I can't say the same for something like a SST-50 @ 5A though.


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## Justin Case (Mar 8, 2012)

LilKevin715 said:


> Perhaps I should have been more clear with the linked thread. It was mentioned in reguards to regulated runtime.
> 
> There is no doubt mags do have resistance, but 0.1 ohms seems a bit much in a setup such as mine. CKOD measured the resistance of a stock tailspring (#1 and biggest offender) and obtained a value of 0.027 ohms. That seems more realistic as my regulated runtime was well over a hour. A 3 X C or D nimh setup with a AMC7135 driver is definately doable and fesible for a XM-L. I can't say the same for something like a SST-50 @ 5A though.



The tail spring isn't the only source of resistance. Other sources include the cell-cell contact resistance, cell to switch contact resistance, switch contact resistance, and grub screw ground resistance. Also CKOD's measurement is the resistance of the wire itself. He did not measure the contact resistances between the spring and the tail cap, nor between the spring and the bottom cell. Of course his conductor measurement will show low resistance. He's checking the resistance of a fairly thick gauge wire. Contact resistance is very different.

See this link to get an idea of how bad parasitic resistance can be.


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