Linger Special + SF L2M SS = Heat Problem?

I just got my Linger Special from Nailbender and my stainless steel Solarforce L2M. The dual XPG-R4's get really hot, much much hotter than Nailbenders SST-50 drop-in.

I have the SST-50 in a L2P and I'm comfortable having it tailstand on high for 1 hour, I'm NOT comfortable running this new drop-in on high for 15 minutes while in my hand. The drop-in itself just feels way too hot.

I've tried wrapping with heavy duty aluminum foil with a tight fit, and yes it helps but I still would like it a little cooler. I'm about to cut up a soda can and try that soon.

I remember reading something about a copper ring people used on their drop-ins, I can no longer find that thread. Where could I get this ring? I'm thinking of using thermal paste between the drop-in and the copper ring, then inserting in the host.

Is there such thing of something like non adhesive thermal putty? That would make all of this so much easier.

The problem is the SS body itself. SS has very poor thermal conductivity thus will not easily allow heat out as compared to an Al body. Take a look at the values for a comparison:
http://en.wikipedia.org/wiki/List_of_thermal_conductivities

I'm not sure how much a copper heatsink would help in this case but it certainly couldn't hurt but just wanted to point out a potential source of problem in case you weren't aware of it.

Going slightly OT, I too have NB's SST-50 pill (3mode @ 2.5a) and was contemplating either a SST-90 or the Linger special. How is the brightness and throw of the Linger vs. the SST-50?

Thx,
Tim

turboBB said:

Going slightly OT, I too have NB's SST-50 pill (3mode @ 2.5a) and was contemplating either a SST-90 or the Linger special. How is the brightness and throw of the Linger vs. the SST-50?

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I believe the Linger special is like a "poor man's SST-90".
Floody.

turboBB said:

The problem is the SS body itself. SS has very poor thermal conductivity thus will not easily allow heat out as compared to a Al or Ti body. Take a look at the values for a comparison:
http://en.wikipedia.org/wiki/List_of_thermal_conductivities

I'm not sure how much a copper heatsink would help in this case but it certainly couldn't hurt but just wanted to point out a potential source of problem in case you weren't aware of it.

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I was aware steel having poor thermal conductivity, I just want to transfer the heat from the drop-in to the host as quickly as possible. It puzzles me why these drop-ins have ridges when we're supposed to move heat away from them.

Going slightly OT, I too have NB's SST-50 pill (3mode @ 2.5a) and was contemplating either a SST-90 or the Linger special. How is the brightness and throw of the Linger vs. the SST-50?

Thx,
Tim

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The Linger special has no hot spot yet it actually throws a little. The SST-50 obviously throws farther. As for brightness, it's slightly brighter than my 2.5A SST-50, hard to notice unless look really closely. These XPGs has a little green tint to them, not noticeable until you compare them side by side with the SST-50. I prefer the color of the SST-50

Update: Two strips from a soda can improved the heat transfer, the head gets much hotter quicker now. I might leave it like this.

Ive got a buncha old aluminum printing plates I can cut into strips and am going to wrap my nb SST-50 when I get it- its going in a C2 and is reg so I probably dont really need to but am gonna mess with the strips just for kicks..

I had a Linger. It was truly awesome output wise. There was a faint green tint but that didnt bother me. NB says in his specs on this module that he is pushing those XPGs real hard so they do produce alot of heat. But man, that thing lit up a HUGE area from 20 feet back indoors. It really is a cool custome unique setup. I just wish you could get them with a broader voltage range.

The heat on the external side of the light body is a good thing as mentioned though. I dont understand what you mean by getting it to run cooler? Because of the setup its gonna be hot no matter what you do. Unless you pack it in ice or something , maybe it shouldnt be used as a tailstander though . Your hand is a good heatsink .

Using the alum. strips is a good idea. I have tried soda cans and now am trying a cutup baking dish the kind you can get at the supermarket. Its thick yet malleable as opposed to the soda can. What I have noticed in Surefire bodies is that the "throat" where the P60 module drops in is tapered . This seems to be an extra step in machining that would afford a tighter fit for the bottom of the P60 module thus better heat transfer. Another detail not easily noticed that puts SF above the rest. My Fivemega body is straight down the throat so there will be a bigger air gap with the P60 module in there. So 5megas are more economical but not designed quite as well. I am hoping with the baking pan since it is more malleable than the can and thicker than regular foil that it will do a better job of filling in gaps and be more durable in the long run than foil. I also had some thermal paste kicking around. I unscrewed the pill on the P60 and laid down some paste on the threads. I figured a thin layer between the reflector and pill would also help with heat transfer since threads have play also . Hopefully the paste wont lose viscosity with heatup and just run out and make a mess. Its Artic Alumina so we will see.

When I switched to the baking pan as opposed to the can and the AA paste I noticed the body of the light was getting more heat transfer when before it was mostly concentrated on the head. Hopefully the 18650 I am using can deal with the extra heat? I am thinking this is a good thing though and I am getting even better heat conductivity ? Seems like the outside of the head and body are heating up a bit quicker also . Its all subjective here though. I have an IR temp gun , maybe I will spend some time trying to get some readings (external )

Got a quick question for you Linger special guys. Does the linger special module have any donut effect in the beam?

Well, more than one. The center clutter is definately there on a wall, but not too noticable in actual use, especially outdoors. I'll live with the center clutter to get the huge bright coverage that this drop in gives. It behaves more like a super wide optic than a reflector light in that the brightness is nearly constant from edge to edge.

John F

That answers my questions. It NB could get rid of the artifacts, I may consider this drop in. Near constant brightness from edge to edge is nice to have in a floody light.

JohnF said:

Well, more than one. The center clutter is definately there on a wall, but not too noticable in actual use, especially outdoors. I'll live with the center clutter to get the huge bright coverage that this drop in gives. It behaves more like a super wide optic than a reflector light in that the brightness is nearly constant from edge to edge.

John F

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Hmm, I honestly dont remeber center clutter or artifacts . You have the 2 hotspots overlapping and it creates an aincredibly huge hotspot and yards of spill but I dont remeember donut holes of little artifacts or shadoy less brite spots everywhere. considering it is one reflector dealing with 2 leds I htought it was pretty darn smooth with a little bit of a figure eight pattern going on.

Liteskr42 said:

I dont understand what you mean by getting it to run cooler?

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What I mean by running it cooler was, moving the heat away from the drop-in as quickly as possible so the heat build up isn't as much so I'll be able to run it a little longer.

Hopefully the paste wont lose viscosity with heatup and just run out and make a mess. Its Artic Alumina so we will see.

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It'll take a lot of heat to make the thermal paste runny, we're talking over 200 degrees celcius.

shilent said:

I just got my Linger Special from Nailbender and my stainless steel Solarforce L2M. The dual XPG-R4's get really hot

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Heat seems to be a "feature" of the XP-G's.

I have a single XP-G R5 drop-in and it gets hot very quicklly in my Solarforce L2 and L2P bodies.

It's much hotter than any of my other LEDs and the heat coming from it reminds me of the heat that comes out the front of my incan drop-ins.