Copper will absorb heat faster. In this case it's not a benefit. No matter what heat is heat and Copper will reach the "too much heat" point faster than Aluminum. Actually, once heated, Copper will hold it's heat longer than Aluminum. Well, ok, Copper will store more heat than Aluminum, given that the heat sinks are the same size, just because Copper is better at transferring heat and it will store it better as well, so if it has not way out, it actually will get hotter faster than Aluminum, which resists heat a little more than Copper.
Point is, without some form of transfer out of the heat sink to somewhere else, it gets hot and stays hot. LOL, I've got a headache again.
dang you guys really opened my eyes up… got a lot more to think about now.
The biggest prob I am having is how the cast heatsink serves as a screw-down sandwich plate for the LED. Its got those 3 screws to clamp the whole thermal assembly together. with 4P-18650 lying flat at the bottom, theres a lot of room for cooling. But the problem isn’t space… its how to mount a heatsink firmly against the LED, and press that flat up against the reflector dish. All while keeping the LED centered at the focal point.
There are a LOT of CPU heatsinks out there. Heat pipes are something I am taking a close look at as well. Oh yeah… if you can solve the heatsinking concerns an SST-90 would annihilate the dark in a reflector this size. But I am looking more for XML throw… at least for now. At $24 / ea for the host, a second SST-50 or 90 build would not be too far out of reach.
Thanks Peter for the direct copper bond suggestion. Sadly I dont know how to do that. I have tried several times to reflow cree LEDs onto various aluminum stars… so far I am like 0-5 or 0-6. I either overheat the star, or I jostle the LED so it slides & squirms all over the ####ing (!!) place when the solder flows.
Give me a couple days to sort it all out… Its a lot to take in all at once.
Good luck with it kramer5150, I hope you can solve the heat issues, and you can adjuts the focal lenght to get the best throw, it must be impressive with that diameter and depth of the reflector.
Best heatsink for homebrew star mount is those cylindrical ones for CPUs (easiest to get are intel stock units and they have copper core, <10$ on ebay). Even the fan should run (slowly) wired into the cell. But just to contrast, this already has better heat transfer than 90% of flashlights.
I am leaning towards copper bar stock (maybe with heatsink fins cut round it) for additional heat sink mass and a low power consumption laptop fan with perforated side walls to vent the hot gasses out.
Need to research fans now…. Does anyone have any suggestions for a low voltage fan? Some of you are very PC savvy, hoping theres an easily solution to be found. I don’t think I need a wind tunnel, just a small fan to vent out the hot gasses.
IF you can find a fan, why not keep the stock heat sink, and add the fan/perforations? As agenthex says, its much better heat sinker than most normal torches, if you force the hot air out, it should be pretty good as is, or add the fan/perforations and if possible, add some more mass to the back of the heatsink. If a 501b can run an Xm-l, that huge hunk of ally should do ok.
if you need any PC heatsinks I have a box of them in my garage for the price of postage. I have a compulsive urge to scavenge anything useful from old PCs in dumpsters
Some of them are probably big enough to cut the fins off in the middle, bolt it to the back of the existing HS and then hang the finned parts out of the side/ top.
battery pack looks good. I find roughing up the surface with a file or dremel for a little bit first helps, then I tin with some solder. I’m usually holding the wire I’m soldering with a pair of pliers, so touching those to the cell after making the join is another way of wicking away the heat. I’ve managed with a crappy 50W radioshack iron before (hoick spit), so it’s not too difficult.
WOW I didn’t know fans were that efficient. THANKS I think thats my solution right there.
I can get a pair of those, blow cool air into the box from two intakes. Theres enough room inside to wire up 4 eneloops and run the fans on a completely separate dedicated circuit. 2 fans parallel will draw a mere .16A, that wil run for ~12 hours with eneloops.
The plan is to run the XML with an east-092 driver I pulled from my HD2010. Hopefully the solid core 22AWG wires, solder and OEM switch will throttle enough current to keep things under control. This driver is a real beast in a low current design, thats why I haven’t considered using thicker awg wire. I just cooked a 4P wired MCE using this driver in a P60 host… OOOPS!!
Hey thanks for that tip. Yeah there are so many pre-packaged, plug and play solutions from the PC industry. My whole problem is attachment and alignment. I can’t think of a way to attach a CPU heatsink using the OEM mounting screw locations and align the LED centered in the reflector.
Use the original as a drill template for your holes,once you know its position relative to the host. Or try the fans and stock heatsink first and see how it goes….
Frankly I don’t think this even needs a fan since the cooling will already be far superior than on most other lights, but the 12v fans will run at lower voltage (albeit slowly). These are units designed to cool >100W (though w/ fan) and this is maybe 10W. It looks like the size of the intel unit above is similar to the neck diameter on the light so press fit might be possible with some tape to buffer the gap.
If I might make a suggestion on design: single li-on cell in a holder charged by a standard li-on charger. All you need to do is hook up the internal holder to the charger with 2-pin connector (one side solder to the holder, one to the +/- on the charger). Easy to use (just plug it in) and parts are things you might already have. The project should cost <$20 total excluding charger and something anyone can do a couple hours.
If the packaging allows for it, you may wish to have one blowing in, one blowing out - with the heatsink fins in the middle.
You could also probably use the existing battery pack for power, and they would just spin a bit slower than spec; a lot of the Airsoft mask fans are 12v fans being run at 9v. That would probably simplify the build a bit, too.
