High Level Heatsink Design

[thebouljello]

I just linked two examples that will do as you ask without a fan. So don't tell me you're reading my posts. You clearly have precisely no interest in "high level heatsink design"

Hopeless.

In your first reply, you said you use the rail mounts with a CPU cooler, and I have never seen a CPU cooler without a fan. The product in the digikey link includes a fan, so it is out of consideration.

You were good up until you delegitimized yourself by being condescending and calling this hopeless.

 

[thebouljello]

Well you made me look it up and the spec sheets posted for the nubm44......not that they are even correct......show 65C as max operating temp so 149F rather than 125F

Interesting. The only specs I could find for it are bits and pieces from google searches and the data from DTR's posts. How do you know that they are incorrect?

 

[RedCowboy]

I looked at the spec sheets attached to sales adds on ebay which have a reputation for being from other diodes and being less than accurate but I expect it's in the ballpark. Personally from my many hours of lasing with this diode I can say that 125F has not been a problem for me but that's no guarantee of what the actual manufactures max temp really is.

I have seen tests where chilled diodes reach higher output and output appears to be reduced with increased temp ( at our overdriven levels ) so I normally shut my hand held units down when they start to feel warm in my monkey paw.

Reducing your current from 4.5a to 3.5a makes a big difference because there's a bottle neck at the diode itself or so it appears in my testing, but I like max output for short duration ( 1-5 min ) so I use a large sink and drive @ 4.5a .......... if you go with your 3.0a plan you should get more stable output with a good heat sink but for real continuous use I would want a fan over fins to maintain as low a temp as possible........without using TEC/ect.... So your plan to go with 3.0a is a good one if you want continuous duty.

 

[thebouljello]

I looked at the spec sheets attached to sales adds on ebay which have a reputation for being from other diodes and being less than accurate but I expect it's in the ballpark. Personally from my many hours of lasing with this diode I can say that 125F has not been a problem for me but that's no guarantee of what the actual manufactures max temp really is.

I have seen tests where chilled diodes reach higher output and output appears to be reduced with increased temp ( at our overdriven levels ) so I normally shut my hand held units down when they start to feel warm in my monkey paw.

Reducing your current from 4.5a to 3.5a makes a big difference because there's a bottle neck at the diode itself or so it appears in my testing, but I like max output for short duration ( 1-5 min ) so I use a large sink and drive @ 4.5a .......... if you go with your 3.0a plan you should get more stable output with a good heat sink but for real continuous use I would want a fan over fins to maintain as low a temp as possible........without using TEC/ect.... So your plan to go with 3.0a is a good one if you want continuous duty.

That gives a good estimate, especially considering the personal experience that you have with this diode.

I would most likely operate the diode at 3A. From yours and the other replies I have read in this thread, it seems like running this diode continuously without a fan is not viable. However, before I dismiss the idea, I want to draw attention to the heatsinks I found in this link: https://www.newark.com/w/c/led-ligh...results/2?sort=P_ATT_BASE_VALUE_1000427_EN_US
They are intended to be used with LED fixtures, so they are bigger and have very low thermal resistances, and they could possibly be used to run the diode continuously. Of course, some machining may be necessary. Thoughts?

Originally, I wanted to design a heatsink, but I am realizing that a custom make would be very complicated and expensive. Therefore, I am heading in the direction of buying heatsinking equipment at this point.

I appreciate the input.

 

[Lifetime17]

Hi,
sometimes bigger is better for some applications in our field.
Rich

 

[RedCowboy]

@ thebouljello -That link goes to Newark site but not a specific heat sink and I have not done much testing @ 3.0a but I can tell you what your output and waste heat with a G2 lens will be on average.

4.5a = 7.4w light and 14w waste heat
4.0a = 6.7w light and 12w waste heat
3.5a = 6.0w light and 9w waste heat
3.0a = 5.2w light and 8w waste heat
2.5a = 4.3w light and 6.4w waste heat
2.0a = 3.3w light and 5w waste heat

@ Rich- Nice looking hosts/sinks

 

[thebouljello]

Hi,
sometimes bigger is better for some applications in our field.
RichView attachment 68264View attachment 68265View attachment 68266

Those are nice. I really like the style of the one in the last pic.

 

[thebouljello]

@ thebouljello -That link goes to Newark site but not a specific heat sink and I have not done much testing @ 3.0a but I can tell you what your output and waste heat with a G2 lens will be on average.

4.5a = 7.4w light and 14w waste heat
4.0a = 6.7w light and 12w waste heat
3.5a = 6.0w light and 9w waste heat
3.0a = 5.2w light and 8w waste heat
2.5a = 4.3w light and 6.4w waste heat
2.0a = 3.3w light and 5w waste heat

@ Rich- Nice looking hosts/sinks

That helps put it into perspective for choosing an operating point. I'm gonna end up picking an operating point or heatsink, then basing the other off the decision.

Sorry about the bad link. Here's a link to a specific heatsink instead of a list of search results

https://www.newark.com/wakefield-solutions/spirled-9680/spir-led-heat-sink-96mm-dia-80h/dp/28AH9455#anchorTechnicalDOCS

It has good thermal resistance, but would need some machining to accommodate a copper housing module. Machining it may decrease the thermal resistance though.