100w LED array heat sink?
- Thread starter Lon
- Start date
deadrx7conv
Enlightened
Looks like a good housing to weld a large heatsink inside. Other option is a waterproof fan and drilling a couple vent holes.
So best I can figure the housing has about 400 sq inches exterior surface area.
Deadrx what kind of heat sink would you weld to it? So you dont think the housing is enough?? I have a round finned 1.5" deep heat sink and a fan that runs it now, it doesnt seem to have near the 5 sq inch per watt surface area.
Sorry for so many questions, I just dont want to burn up my array.:o
Deadrx what kind of heat sink would you weld to it? So you dont think the housing is enough?? I have a round finned 1.5" deep heat sink and a fan that runs it now, it doesnt seem to have near the 5 sq inch per watt surface area.
Sorry for so many questions, I just dont want to burn up my array.:o
deadrx7conv
Enlightened
The above is the dimensions for a China-sourced typical 70w-100w outdoor LED flood light. The bottom 112mm is the driver. Notice that your recycled housing is lacking fin count surface area.
I'd carve up ANY large CPU heatsink that would fit there. If you can drill/tap, then you can hard mount your heatsink/fan combo and see how it goes. You want to make sure there is some type of thermal connection between the heat-sink and that housing. Otherwise, the housing turns into an enclosed convection fan-oven. Welding is probably the best way to make that connection. But, we here tend to use thermal epoxies as another option.
The other option is to do some backyard 'aluminum pouring'. Fill the housing and mount your LED directly to the aluminum fill.
If you're driver is variable, start with a lower 30-50w(if the LED lights) and move up from there. Monitor the temps will determine how good your heat sink method is.
Something like this cut to fit and mounted inside?
http://www.heatsinkusa.com/categories/10.000"
http://cgi.ebay.com/370491621077
http://cgi.ebay.com/300571764120
Other good sources of heatsinks are burnt out car stereo amps or home stereo receivers.
Last edited:
deadrx7conv
Enlightened
It should work. Water filled copper pipe is an excellent way to move heat from the inside of the housing to the outside, and affordable too.
But, like anything, you should test the LED at different wattage levels monitoring temperature.
But, like anything, you should test the LED at different wattage levels monitoring temperature.
deadrx7conv
Enlightened
Very creative and original design!
Make sure you use a pipe plug to mount the LED to. The pipe cap might need a little filing to flatten it.
I just don't see enough surface area for 100w yet, even with the mop of copper wire.
You could try to use 'baseboard heating' which is finned pipe and might give you the surface area you need, or try the slip over pipe fins. Check with your local hardware store, plumbing and heating supply, or plumber/HVAC guy for scrap pieces.
Baseboard heating pipes can be 'manifolded' together either vertically or horizontal across the back of that recycle light housing.
I still think that the best mount for your LED is a recycled heatsink, from a Pentium4 or equivalent. You can drill though the back half of the CPU heatsink to push that "pipe idea" and the pipe should be 'press fit' into the CPU heatsink along with being pressed into the light housing's hole. Braze/weld it all together once you set the LED height in the housing. Don't forget that the 'metal reflector' is also 'heat sink area' too. So, you want to drill several small holes around the CPU heatsink and attach the reflector to the heatsink.
Make sure you use a pipe plug to mount the LED to. The pipe cap might need a little filing to flatten it.
I just don't see enough surface area for 100w yet, even with the mop of copper wire.
You could try to use 'baseboard heating' which is finned pipe and might give you the surface area you need, or try the slip over pipe fins. Check with your local hardware store, plumbing and heating supply, or plumber/HVAC guy for scrap pieces.
Baseboard heating pipes can be 'manifolded' together either vertically or horizontal across the back of that recycle light housing.
I still think that the best mount for your LED is a recycled heatsink, from a Pentium4 or equivalent. You can drill though the back half of the CPU heatsink to push that "pipe idea" and the pipe should be 'press fit' into the CPU heatsink along with being pressed into the light housing's hole. Braze/weld it all together once you set the LED height in the housing. Don't forget that the 'metal reflector' is also 'heat sink area' too. So, you want to drill several small holes around the CPU heatsink and attach the reflector to the heatsink.
That mop of wire is not even be sufficient for 20W, not to speak of 100. Tiny surface area.
There is no cheaper way to cool such a fixture than a heatpipe cpu heatsink. You can get nice big ones for $20, which are good enough to cool away 100W without getting too loud.
And Lon, 40x10mm fans are great as noisemakers, but you will be much more happy with any fan >80mm.
There is no cheaper way to cool such a fixture than a heatpipe cpu heatsink. You can get nice big ones for $20, which are good enough to cool away 100W without getting too loud.
And Lon, 40x10mm fans are great as noisemakers, but you will be much more happy with any fan >80mm.
blasterman
Flashlight Enthusiast
- Joined
- Jul 17, 2008
- Messages
- 1,802
Cap mounting LED arrays this way only works up to 5watts or so. I've tried it - doesn't work. Conceptually the copper cap the LED is mounted to works as a flat piece of metal, and even at 1/8" of an inch thick it can't radiate thermal from the big emitters fast enough. Then the junction between the cap and the copper pipe comes into play. So, drop the pipe idea unless you want to point it at things to set them on fire :-) You won't need a thermal probe because the solder joints on the array will catch fire in a few minutes and melt anyways.
Even if the pipe were a solid core of copper it would need an extensive array of thick cooling fins with 1/4" junctions directly to the 'solid' rod. Even then, running the modeling in my head my intuition is there would still be issues. You have no idea how much thermal these big arrays generate. 20watters are bad enough.
No....looks about half that. The inside is sealed so it doesn't count after it warms up and the fins aren't long enough.
Still, if the wall of the fixture is more than 1/4 thick your original idea of machining it and mounting the emitter on it might be the best.
Otherwise, the only way to practically cool these fat, inefficient chiense arrays is via active cooling. The older Pentium style passive sinks typically used on Dells work better than modern ones with thinner bases and thinner fins. Then stick a super high RPM 80mm on it.
Insert my scripted lecture that you can usually get more Bridgelux lumens per dollar than these Ebay arrays at about 40% less energy consumption.
Even if the pipe were a solid core of copper it would need an extensive array of thick cooling fins with 1/4" junctions directly to the 'solid' rod. Even then, running the modeling in my head my intuition is there would still be issues. You have no idea how much thermal these big arrays generate. 20watters are bad enough.
No....looks about half that. The inside is sealed so it doesn't count after it warms up and the fins aren't long enough.
Still, if the wall of the fixture is more than 1/4 thick your original idea of machining it and mounting the emitter on it might be the best.
Otherwise, the only way to practically cool these fat, inefficient chiense arrays is via active cooling. The older Pentium style passive sinks typically used on Dells work better than modern ones with thinner bases and thinner fins. Then stick a super high RPM 80mm on it.
Insert my scripted lecture that you can usually get more Bridgelux lumens per dollar than these Ebay arrays at about 40% less energy consumption.
Thanks Blasterman, very good info, I will search out your lecture. I started with this ebay array cause the guy sold it, a finned heat sink, fan and some lenses for 55 bucks, I have some bridgelux coming, and spoke to a tech there, i know they are better, just wanted to experiment on the cheapy as I will likely destroy it as Im learning.
The fixture is right at 1/4" thick. I am going to a Comp. shop to get some old sinks, will rework and post up, thanks ALL for the advice, its likely saving me big time.
The fixture is right at 1/4" thick. I am going to a Comp. shop to get some old sinks, will rework and post up, thanks ALL for the advice, its likely saving me big time.
deadrx7conv
Enlightened
You seem to be right on track now. Add a waterproof fan or two and see how it runs. Gelid, Nanoxia, and ADDA have waterproof fans if its for outdoor usage.
Google heat-sink lapping to smooth out the LED and heatsink mating surfaces. Don't forget to use artic-silver or equivalent thermal paste on the LED/Heatsink surface. You should also use the thermal paste along the heatsink/housing mounting area(or just braze/weld the heatsink to that housing).
Is this for indoor or outdoor usage? what type of power supply or driver do you plan on using?
Google heat-sink lapping to smooth out the LED and heatsink mating surfaces. Don't forget to use artic-silver or equivalent thermal paste on the LED/Heatsink surface. You should also use the thermal paste along the heatsink/housing mounting area(or just braze/weld the heatsink to that housing).
Is this for indoor or outdoor usage? what type of power supply or driver do you plan on using?
