Help? Cxb3590 temp?

One eye gen

One eye gen

Member
Guys I'm having trouble finding out the running temperature of CXB3590. 50w per cob will be what they are ran at. This information will help determine what I use for a frame/substrate. Any help will be greatly appreciated.

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What type of heatsinks are you using? I have 3 4x cxb3590 fixtures. They all are framed with 1/2" angle aluminum.
 
Yeah I'm trying to figure out the CXB3590 operating temperature because I have something different in mind. I will be sharing the build on here after
 
One eye gen said:
Yeah I'm trying to figure out the CXB3590 operating temperature because I have something different in mind. I will be sharing the build on here after
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Not quite as easy as that. First you have to know the efficiency of the CXB3590 then you have to know how many watts you will be running to it. Then you have to know the thermal resistance of the heat sink used. Once you know those factors you can calculate how many degrees over ambient temperature the LED will run. So you have the 50 watts part now you need to figure out the efficiency of the LED they should add that to the data sheets but they don't. Going to be around 60% is my guess so that would mean you need heat sinks that can handle at least 20 watts of heat. 30 watts gets turned to light 20 watts is heat. Now the better the heat sink the lower the cob will run temperature wise. This will always be over ambient temp their is no one set temperature the cob will run. So if the of heat sink calculation is 20 over ambient temps then a 25C room will have a cob temp of 45C, a 15C room will have a cob temp of 35C. Here is a link to a page that explains how to calculate for proper heat sinks. https://www.led-heatsink.com/thermal-calculation
 
Thermal resistance is about .85 for that pin fin so you are looking at about 17 to 20 C over ambient with those heat sinks. That about 60 F to 70 F so in a room that has a temp of 80 degrees the cob would run 140 F to 150 F @ 50 watts running @ 60% efficiency
 
Don't skimp on sinks, they last forever. I would set them up on 150mm pin fins, nice and cool.

Wasn't aware Cree had come so far with their efficiency numbers. If I remember correctly CD bin was about 50% efficient. What are the bin options these days?
 
One eye gen said:
Too late to switch to 150mm I already placed an order for 45
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They will provide decent performance. The difference between running cool and warm isn't really a game changer, it's just a way for the enthusiast to squeeze a little more light from a rig.
 
One eye gen said:
So it may be possible for me to build a acrylic frame..... am I right?
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Pretty close to the max temperature plus acrylic breaks pretty easy. Polycarbonate might be a better choice as it is more impact resistant has about the same temp rating I believe.
 
I'm thinking about making a 42x42x .125 inch square on the bottom of the fixture. And cut holes to allow 15 cobs but secure the lenses to the heat sinks having the screws pass thru holes in the acrylic. While having a second piece of acrylic with matching dimensions except for the top acrylic layer has bigger holes to not impede air flow and stay passively cooled
 
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I can provide additional support throughout the fixture with all thread and washers. Think about when we go to the banks and they have that plexi with bolts securing the angle changes
 
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