I really am shocked that at this point none of the usual companies has applied heatpipes to a flashlight design. It would be relatively easy and if they can sell $30 CPU coolers with 6 heatpipes, I don't see why it can't be done on a sub-$100 flashlight. The technology is there and I wouldn't think the process would be all that difficult to sort out.
The funny thing is that some of my flashlights put out more heat that some of my computers. :)
It could be.
But. Heatpipes only work well when they are in a fixed orientation. And computers normally don't move in use - flashlights do.
hadn't thought of that - so i guess that would be so the coolant collects in the proper place from gravity?
that'd be ok w/ pistol grip lights...usually...
There is really no means of active cooling that works well in a flashlight. Heat pipes do need to remain stationary and fans mean openings in the light, for air flow. Fins on the outside are only passive cooling. The real deal is that flashlights were never meant for these high powered emitters. Short time use is the only way to keep them from overheating.
hmm
or dry ice 
(talk about dangerous lol)
That’s not true. Modern heat pipes do not rely on their orientation.They may be slightly more effective in one orientation than the other, but they still work.
I have yet to see any evidence that they work well in any orientation other than the one they were designed for. Heatpipes rely upon mass transport - they quite literally move the heat from one place to another. Capillary action is not a quick way to return the coolant.
if somebody wants to test one, i'll send one for the cost of shipping
edit: i have two sizes, (very) roughly, the size of a small apple and (height) a large grapefruit
Those 15mm fans look awesome. The shipping cost is the only thing allowing me to resist. I have a few 20x8mm fans, member on another forum found them at a local shop for cheap.
Have you looked for any evidence? Look under the $10 I sent you last year. You’ll probably find it there.
For everyone else, The difference is a few degrees C. I've tested it myself on high-end CPU heatsinks that rely almost solely on them. Even upside down I was only getting a 7C difference with a 75w load and that could have been in part due to less mounting pressure.
Here an article on the different types of heatpipes: http://www.frostytech.com/articleview.cfm?articleID=2466
intuition (not very accurate) says there would be a difference (how much?)
but if heat pipes were designed for a flashlight, not a cpu
ie radially, all around the head - then some of them would always be functioning (assuming you're not pointing the flashlight down)
a DIY'er could build such a heat pipe system (I have a nice pipe flaring tool :) ) but as far as adding coolant goes....???? admittedly, I can't flare cpu size heat pipes, but I think I have a 3/8" end...
I'm imagining my advance auto spotlight w/ 100W HID, 3 cpu heat pipe sinks and 26650 battery pack
i need a second job lol
OH - 20mm fan isn't bad at all! the diagonal measurement is a bit much, but I've already taken the grinder to a plastic fan frame - they're over built enough to remove a LOT
20mm X 20mm x 6mm - 5V
http://www.mouser.com/ProductDetail/ADDA/AD2005MB-K70S-LF/?qs=sGAEpiMZZMvuXzJ9NcThaqBG%2fSi4pPVaBpKkRsBtmaI%3d
10mm x 10mm x 3mm - 3V
http://search.digikey.com/us/en/products/UF3A3-700/259-1520-ND/2417176
12mm x 12mm x 3mm - 3V
http://search.digikey.com/us/en/products/UF3C3-700/259-1522-ND/2417178
15mm x 15mm x 3mm - 3V
http://search.digikey.com/us/en/products/UF3F3-700/259-1523-ND/2417179
PPtk
nice - they actually say 3.5V on the spec sheet
I wonder if 4.2V would toast them. I've actually toasted some cheap fans (sort of) on purpose experimenting w/ fans for my camper It took quite a bit of over voltage....probably doesn't correlate much though since I only know how they were configured at purchase (no specs)
I have a bunch of US quarter (coin) sized copper heat sinks (for ram/vga) - this might actually work...
effective...maybe - cost effective...maybe not - fun...YES
From the article you posted the link to:
"The crux of the situation is that some wick structures are more efficient than others, and some have limitations with respect to orientation and gravity. "
Also concerning the grooved wick heatpipes: "Manufacturing costs are low with this type of heatpipe because the grooves are easier to make, however the technique is much more susceptible to gravity and can be orientation specific in use. In general, Thermolab state that vertical orientation is best. "
So it seems that they say orientation depends completely on the type of heatpipe manufactured.
Also, when you tested yours, did you test it as you would a flashlight, bouncing it around while carrying it and moving it from vertical to horizontal and back, to see how it worked in that manner? Just asking...
From what I have read over the years, orientation somewhat important. Also when you see how these pipes are made, the manufacture of them would be prohibitive from a DIY standpoint. The type of fluid used is dependent on the target temperature (different fluids for different temperatures) and the proper vacuum needed to apply, before sealing the pipe, might also be difficult to do at home.
I seriously doubt that 4.2V will hurt them.. If you're worried about it though, toss a el'cheapo diode in series with the fan. The diode will drop about .6V, bring it down to 3.6V...
We're talking roughly 50mA, so the heat is no worry...
.05A * 0.6V = 0.03 Watt
PPtk
I wouldn't be too worried about it (said the man that has bricked fans)
what would happen if you just paralleled it w/ the emitter - it'd be right on voltage spec and just rob a bit of current from expected drive levels?
direct drive w/ thermistor is probably preferable...
btw - i know of at least one cheap technique for making an air intake water resistant
pumice
I have a bait bucket aerator that was made to be inside the bucket (but not submersed)
they put porous stone on the air intake so that splashing water in the bucket can't flood the inside of the unit
admittedly...that pump is designed more for pressure than throughput. a micro fan probably can't draw much (if any) air through pumice....
No, it’s not just asking. It’s being a smartass. I read the article. I see that certain types have certain drawbacks. But it show that orientation is not a must. You are ready to shoot it down without accepting the feasibility of it and I don’t understand why.
I said nothing about it being DIY. I said manufacturers.
I'd probably go for the dropping diode before I would parallel a fan with an emitter. Fan's are very strange devices to a constant current regulator. They look like they are switching on and off very quickly - think PWM - to the regulator. I've seen very very strange things happen when a fan is driven by a constant current supply. The only saving grace in this instance is that the fan is such a small portion of the total current draw. I still wouldn't suggest it though. The thermister would probably work as well, but the nice thing about a diode is that it always drops the same amount of voltage no matter the current and it can handle a lot of power in a really small package. Even cheap diodes can usually operate just fine with a junction temperature of 150 or 175 C.
As for the pumice - you're correct about the pressure being a problem. These micro fans move a lot of air for their size, but they can't handle ANY static pressure. You would get pretty much 0 air movement with a restriction like that in the flow path.
PPtk
Yes, smart ass is correct. Just cannot seem to keep my nose clean round here, or anywhere else for that matter. It just naturally comes out. That’s not an excuse, just a plain fact.
Shouldn't have been said, but it was. You're welcome to your opinion just as anyone is and it's not my place to shoot it down.
didn't think of that (pwm), but yeah, that makes sense and sounds bad lol
I had been originally been thinking plain old resistor (and sort of 'heard' that when you first said diode) but diode makes much more sense.
very true on the issue of pressure. even the 60mm and 40mm fans I'm working with now don't like being restricted inside the host. they still move a decent amount of air, but nowhere near what they do in a computer case - makes them louder, too.