I have been working on a DIY searchlight, and am worried about proper cooling. I am using 4x LMP LHP73B. What would be suitable for cooling this build? I preferably want to avoid water cooling.
Thanks in advance.
1 Thank
I’d like to build a light like this someday. I’m interested in what others think about cooling. I bought a little Peltier cooler kit that I’ll eventually try out to see if it could work.
It might help if you mention more about your design. Do you have room for large heatsinks? Power source? Is water resistance a concern?
For this power, you would need some quite powerful cooler, linke a high end CPU Cooler or something like that.
Are the 4 LEDs seperated or very close to each other?
If they are seperated, 4 smaller, cheaper CPU coolers probably would do the job well. The aren’t super heavy, but need space, of course
I havent built it yet, (or even ordered the parts for that matter) so the design always has room to change. Right now, I’m thinking about using 16mm MCPCB’s that are 3cm apart, with a 45mm x 40mm reflector on each LED (90mm x 90mm in total). I was looking at CPU coolers, but since the LEDs are not very seperated nor close together, I have had a hard time finding anything.
My design is going to be an open-air build. I don’t really care about portability (as long as I can lift it with 1 hand), nor water resistance. I plan on using a 12v airplane battery as the power source. Large heatsinks aren’t a problem.
Get an aluminum U channel, about 2 ft long, 1.5x1.5 or 2x2 in, then get a smaller channel, same lenght, put it inside, make sure they are firmly pressing against each other, no air gaps, use as many screws or rivets to acheve that. that will become your wind tunnel, side of the channels will be your cooling fins, a fan on one side will blow air thru the tube and cool those fins, you can put 2 fans, one on each side so one pushes air thru another one pulls, this way airflow will be more uniform thru the lenght of the channel, Use as big of a star aka mcpcb as you can get, it is the most critical point of heat dissipation, obviously use direct heat path stars, with around 50w per led you need that. use 2 or 3 screws to mount them firmly to the channel. Do not use thermal paste as a gasket, you want more metal to metal contact, this is most efficient heat transfer solution, paste should be only filling up tiny air gaps, it has a lot lower heat conducting ability than metal to metal contact when firmly pressed, but better than air.
I have build 200W uv light using this design over a decade ago, it still runs. so I know it works if done properly.
2 Thanks
Oh, and obviously close the open side of the larger U channel with anything, as long at it is airtight. You can also heatsink drivers on same channel, either between leds or on either side.
Or just buy one of these:
Plus one fan on each end.
THey seem to be available under the name “Tunnel Heat Sink”
How hard do you want to drive the LEDs, btw?
Maybe put them on the biggest MCPCB you can find - or/and put some flat heatpipes between the LED and the heatsink to spread the heat further.
2 Thanks
I had no idea those were available, that is even better than diy version.
1 Thank
I love the idea, but thats not really what I want to accomplish. I preferably want a more throwy light, so i want the LEDs in a square formation. If thats not possible though, ill totally use that idea.
Thanks
This is more what I was thinking about. Only problem is, this is ~$500. I like the big copper plate though.
I want to drive the LEDs at 15-20A (in series). I’ll totally put them on a big MCPCB.
Heatpipeas are good for stationary devices, they do not work in all orientations equally, hot side has to be lower than cold for them to work properly, servers and computers are not moving around and flipped upside down. that heat set up on the picture above is the opposite of what it has to be, it was designed so the cooler to sit above the processor, they rely of gravity to return fluid, flip it upside down and it no longer a heatpipe, it acts like a solid heatsink, with much lower efficiancy
That is no problem use 2 shorter tunnels next to each other, with 2 leds on each, with proper optics it does not really matter how far leds are, within reason of course, 3 or 10cm wont matter much, optics is what matters most with throwers. best tir for throw is ledil seanna, but it is pretty big and complex, but it can make thru 5 degree beam with large leds such as 7x7 die size, (xhp70), nothing else comes close.
Thanks so much! I never even considered using 2 tunnels next to each other.
I take it back that is what I want to accomplish. Thanks!