Surefire L4 OSRAM Ostar Mod

rush

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Mar 30, 2008
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Germany
My Surefire L4 OSRAM Ostar Mod aka "Flaming Fields"

The OSRAM Ostar 6 die emitter in its higher luminous flux bins is the emitter with the highest light output available today. So sure enough building a flashlight around this beast is more than tempting. Since i won't be lugging around a large torch on a regular basis, i rather wanted something small enough to be sort of an EDC. Lots of useable smooth light is what i had in mind and this is just what a multi-die emitter really "shines" (pun intended :)) at.

Full credit for the the idea behind this mod has to go to ARCMania who has pioneered building an Ostar into the KL4. While his great work involved custom parts like a pill to house electronics and hold the LED, i am making use of the existing parts of the Surefire L4 host. The KL4 is pretty much the perfect host for this project since it will tightly fit LED and converter with no room wasted.

The Build
Lets have a look at the list of parts that went into this mod:
  • Surefire L4 (Lux V)
  • OSRAM Ostar (Bin QY4C)
  • Blue Shark converter with Remora controller (Sandwich Shoppe)
  • Small piece of copper as heatsink for converter
  • Wires, Polyimide tape, thermal interface materials
  • DIY milling setup
... plus lots of time and patience ;)

1) Opening the KL4 head
The first step is far from being the easiest since the treads on the head are locked with a black sealant. Some people seem to have been lucky and not needing much force to open the head. This one needed both heating and a combination of a vice and a wrench to come apart. Using strong and thick rubber sheets wrapped around the head preserves it from getting scratched in the process.
Once this is done we are removing converter and the Lux V LED, it will probably end up in my small LED museum.

preparationgb7.jpg



2) Milling the head for the Ostar
Looking at the parts at this stage you can see that the Ostar will fit the grooves on the backside of the KL4 reflector. For a perfect fit we need to take off some material though. I am using an ordinary drill in a rig and some small milling tools. To avoid any damage and too much debris inside the reflector i have masked things off with some tape. I also need two slots since the wires to the LED are running at the top of the MCPCB. Fast forward about an hour the head looks as in the picture below.
I also enlarged the reflector opening by a few tenths so the Ostar will go in all the way.

final0009nf1.jpg



3) Other mechanical work
The "LED support" with its two screws will be used in the mod, but it does need two new holes for the wires.
The Ostar MCPCB needs to be sanded down to be slightly smaller in diameter than the inner diameter of the head.
Some more sanding is necessary on the converter boards to mate with the LED support and the battery contact part.

4) Assembly
Blue Shark and Remora are stacked as tightly as possible. I am using isolating polyimide (aka Kapton by DuPont) tape wherever unwanted electrical contact could be possible. A cut piece of copper attached to the top of the DC-DC converter chip will make thermal contact to the aluminium LED support.
A cut piece of polyimide shields the top of the Ostar against the milled reflector backside, on the bottom thermal grease is used to help removing the heat from the LED.

final0003cq5.jpg

final0007qj8.jpg



5) Todo
The whole assembly is still a little too high and the head will not screw together all the way. I will probably remove some more material on the inside and add some thicker O-Ring to seal the head. This does not affect the function of the light at all.

final0014aw7.jpg



Electrical characteristics
The converter is in stock configuration, that means 100% output is 1000 mA to the LED. With the Remora the Shark is turned into a three level clickie at 10% - 50% - 100% output. 100% means about 20 W power at the LED, which is more than the setup can handle thermally. I plan to reduce max. output to about 750 mA.
With freshly charged Li-Ion cells (AW black 750 mA) i am measuring the following input currents to the converter:
Cells....Level.......Iin
2..........10%.......300 mA
2..........50%.......850 mA
2.........100%......3300 mA

Using the L4 body with 2 RCR123, the 100% level is drawing far more current than a standard Li-Ion can handle. The protection kicks in rather quickly as soon as the voltage sags too much and current going up. LiMn (AW IMR 16340) can sustain the high current though.
Runtime with two black label AW on 10% is 1 hour 40 minutes.

Light output
Similar as the stock L4, the modded light has a very floody beam with a very useful hotspot. Artifacts from the 6-die layout of the LED are noticeable on a white wall but not when using the light.
I don't have a way to measure lumens but from comparing with different other lights i can tell that not only it is wicked bright but also putting out much more lumens than anything else i have :D
At 10% the output is around 100 lumens, it is slightly brighter than the stock Lux V L4.
Check out the outdoor "beam shots" below, you can see that the floody beam is lighting up the whole area, i changed the exposure to make them look more as it appeared in reality.
On 100% it easily lights up objects that are further away than 100 m, but with the wall of light in front of you it is actually hard to tell.

L4 Ostar at 10%
dscf0004kv5.jpg


L4 Ostar at 50%
dscf0006hi7.jpg


L4 Ostar at 100%
dscf0008om8.jpg



Summing it up
I am amazed with the wall of light of the L4 Ostar mod, a nice floody beam. The lowest level is more than enough light most of the time, but when you need it you can crank it up and turn night into day. What makes all that special is the pocket friendly size of the L4 when it trumps many larger lights in light output.

If any of you can tell me what generation the KL4 head i have is, i would appreciate it. There is at least one other type of KL4 head/reflector that i have seen here on CPF.

If there is interest i might make a limited few mods for fellow CPF'ers, especially seeing as ARCMania has stated that he would not make any more of them.


Hope you enjoyed it! :)
 

thegeek

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Very nice! Is the converter board the reason the head won't fully close or is it the Ostar board?
 

rush

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Germany
Very nice! Is the converter board the reason the head won't fully close or is it the Ostar board?

Thanks!

Actually it is both the Ostar MCPCB and the converter board(s). The whole setup is tightly stacked inside the head, so the only way of reducing height while using the original parts is to remove more material. I need to loose another 1.5 mm so the head will close fully. This is possible though without compromising mechanical or thermal properties.
 

1996alnl

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Oct 10, 2008
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649
WOW!
That third picture looks like FOUR stock L4's on at the same time.:eek:
That's a serious light you have there. Seeing that amount of light coming out of something that small must seem sureal at times.
Exellent mod.
 

rush

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Mar 30, 2008
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Indeed it is insanely bright on 100% (1000 mA to the LED), much too bright on close quarters and a wall of light when used outdoors ("Flaming fields" :D ). It should be at least around 800 lm (emitter) @ 1000 mA, so that is actually more than 4 Luxeon V L4's :)

I am impressed every time i put it on full power, this is the other light besides my LS 20 that will put a grin on my face when i use it :grin2:

I have been using it strapped to my helmet on mountainbike night rides, 10% output is still more than enough on the double tracks like in the pics above. And turning it on 50% output will pleasantly light up a small curvy single trail even at higher speeds.
 

1996alnl

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Oct 10, 2008
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rush,i'm very impressed with your mod.,and the runtime on 10% output is even more impressive.
As nice as the the L4 is with the LuxeonV it just shows how technology has evolved as far as efficiency goes.

I'm using a AW 17670 cell in my (stock) L4 and it's pulling 1800mA! And actual runtimes are about 40 min. of regulated light then it dims considerably.

I'm seriously thinking of modding this light,it's just that i like the tint so much.

Will your light work with a 17670? If not hows the runtimes on 50% and 100% with RCR123's?
WOW that sucker is bright on high.
 
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rdh226

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My Surefire L4 OSRAM Ostar Mod aka "Flaming Fields"
...
If there is interest i might make a limited few mods for fellow CPF'ers, especially seeing as ARCMania has stated that he would not make any more of them.
Count me in as one very-interested feller!

Dunno how hard this would be, but two variations on the power-curve would be of great interest (to me):

L4: 4% : 16% : 64%

and, to operate off a single RCR123 if possible (Sandwiche Shoppe shows V(in) from 2.7V):

TW4: 2% : 8% : 32%

But i would (AM!) still definitely interested in the 10%:50%:100% version as described!

Hope you enjoyed it! :)
Oh, indeed, I did! Lustfully, even!

KL4's standing by . . .

-RDH
 

cmacclel

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Jul 15, 2003
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Cool mod but :)

-The Board will not be able to boost 7.4v to 21v for long before it overheats and fails.

I Have a shark and Ostar here in front of me on my Test Bed. Here are some readings.

-14.8V 1.5 amps at Power Source .939 to LED
-11.1V 2.0 amps at Power Source .933 to LED
--7.4v 3.3 amps at Power Sourve .900 to LED

Li-Ion cells are typically rated a a 2c Discharge rate which would be a max of 1.5 amps from the AW R123 750ma cell. On high your pulling over 4c which is over double and is not safe.



Mac
 
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cmacclel

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This light needs AW IMR RCR123's in order to use the high mode.


Yes that solved the battery problem but does nothing for the driver board s overheating. This setup with a much bigger heatsink and using 3 cells would shutdown within 10 minutes in the SuperFlashlight V.

Mac
 

toby_pra

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Oct 9, 2007
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Very cool mod! :D

I love those Ostar LED's and according to Mac, perhaps sometimes
there will be a useful setup available...
 

rush

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Germany
Will your light work with a 17670? If not hows the runtimes on 50% and 100% with RCR123's?
WOW that sucker is bright on high.

One cell will only give you the lowest mode, i don't know what the maximum possible output current would be though (somewhere between 100 mA and 500 mA).
RCR123 will only work for a very short time at 1000 mA due to the protection circuit kicking in if you use protected cells. Using unprotected RCR would not be a good idea.
Using IMR 16340 the runtime on medium (500 mA to the LED) is about 30 minutes. RCR would probably be comparable but i don't have numbers right now.

Count me in as one very-interested feller!

Dunno how hard this would be, but two variations on the power-curve would be of great interest (to me):

L4: 4% : 16% : 64%

and, to operate off a single RCR123 if possible (Sandwiche Shoppe shows V(in) from 2.7V):

TW4: 2% : 8% : 32%

I am using the Shark converter together with the Remora UI extension. The Remora has a fixed 3 level control output to the Shark which is set to 10%-50%-100%. What can be changed is the maximum (100%) output of the Shark and the lower levels will decrease accordingly. So instead of 100 mA - 500 mA - 1000 mA to the LED, i can change it to 75 mA - 375 mA - 750 mA for example.


But i would (AM!) still definitely interested in the 10%:50%:100% version as described!

KL4's standing by . . .

-RDH

My offer is still valid, send me a PM please.


Cool mod but :)

-The Board will not be able to boost 7.4v to 21v for long before it overheats and fails.

I Have a shark and Ostar here in front of me on my Test Bed. Here are some readings.

-14.8V 1.5 amps at Power Source .939 to LED
-11.1V 2.0 amps at Power Source .933 to LED
--7.4v 3.3 amps at Power Sourve .900 to LED

Li-Ion cells are typically rated a a 2c Discharge rate which would be a max of 1.5 amps from the AW R123 750ma cell. On high your pulling over 4c which is over double and is not safe.


Mac

Thanks for chiming in Mac, your points are all valid.

An I(out) of 1000 mA is more than this setup can handle for a prolonged time. I have not tested how long it would run until the thermal protection in the switcher IC on the Shark would shut down with overtemperature, but it is probably less than 5 minutes. So the high mode has to be reserved to short intervals.
500 mA I(Out) is usable but some additional cooling (moving air, holding it in your hand) is recommendable to keep the temperature down. I have done a measurement on the outside of the head and it will reach close to 60 degrees C. The body of the L4 is comfortably warm at that time. The test was done with the light laying flat on a piece of wood (low thermal conductivity) at normal room temperature.

This is why i would rather lower the 100% output of the Shark to say 750 mA if you want to be able to use medium without worries.

The only recommendable cell for this setup is indeed the LiMn chemistry (ie AW IMR 16340). First it tolerates the high discharge current and second the LiMn is a rather safe chemistry that does not need a protection circuit that would shut off your light without warning as with protected RCR.


Bottom line is that this mod (at least using the high 1000 mA maximum output) is not useful if you need the longest runtimes and is not child safe. But it is an awesome lot of light in about the smallest possible package.
 

Hallmcc

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Jun 8, 2008
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Raymore, Missouri
Sorry, I don't mean to high jack your thread, however, where did you get your OSRAM Ostar (Bin QY4C) at?

I have a project I need to finish and am two short. My previous supplier quit carrying them.

Thank you in advance.
 

dutchguy2

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Dec 4, 2007
Messages
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the Netherlands and Germany
I bought one of these from Rush and I must say most impressive!

First of all it was very nice to deal with Rush (Martin)

The light is build very well, no flaws what so ever. And man, what a light output :naughty: it is very, very bright for such a small light. Furthermore the size and beam makes it my favorite EDC light.
 

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