Heatsinks for DIY LED lamps

thanks

1M of that heatsink profile was about £60 when I enquired

@SupraSPL -- A while ago you mentioned you were going to try passive cooling some 25W COBS using a 6" length of the 5.82 HUSA profile. How did you get on with that? Any news?

thanks, ukp

Yes I have been using them and they are running very cool, ambient is about 24C, heatsinks are about 30C with no air movement. They are on a dimmable driver but when turned up to full they are 24W ea and 65% efficient.

What leds are you running? was 65% a typo?!

I was considering some individual passive heatsinks for cooling cxb3070 @ 700mA.
Consulting your excel sheet (ty) I see that they are dissipating 24W of heat @ 700mA..

6" of 5.88 profile gives you ~ (6*260)/75) = 20W cooling.
there still cool enough?

Edit for maths.

For 5.88"X6" heatsink, passive cooling at 70cm²/W, I get 22.3W. That is referring to total LED dissipation wattage (heat and light). It would be more accurate if we went by just heat, but the 70cm²/W rule is just a guide. You can use more or less depending on your efficiency. So in your example you have 23.6W at very high efficiency (55.4%) so a 5.88X6" piece would work well.

The 65% example I referred to is the CXA3590 5000K DB. It is currently the most efficient LED available. At 200mA (13.3W) they are 70% efficient or 227lm/W. The driver (HLG-120H-C350B) dims from 20mA to 370mA. At 20mA it draws 4.6W at 370mA it draws 160W. Definitely overkill but the cost was not unreasonable and I am very curious what it can do.

Thanks again dude!
I will go with;
4 x cxb3070 @ 700mA
2 x drivers
4 passive sinks @ 30W max each. Will update when I have started buying, few months

kind regards, thanks for your help etc..

UK PEANUTS

UKpeanuts said:

1M of that heatsink profile was about £60 when I enquired

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That sounds reasonable. A good heat sink is an heirloom. Generations may use it.

Don't forget the only flat of a heat sink is what you make. Make it good and flat.

SupraSPL said:

For 5.88"X6" heatsink, passive cooling at 70cm²/W, I get 22.3W. That is referring to total LED dissipation wattage (heat and light). It would be more accurate if we went by just heat, but the 70cm²/W rule is just a guide. You can use more or less depending on your efficiency. So in your example you have 23.6W at very high efficiency (55.4%) so a 5.88X6" piece would work well.

The 65% example I referred to is the CXA3590 5000K DB. It is currently the most efficient LED available. At 200mA (13.3W) they are 70% efficient or 227lm/W. The driver (HLG-120H-C350B) dims from 20mA to 370mA. At 20mA it draws 4.6W at 370mA it draws 160W. Definitely overkill but the cost was not unreasonable and I am very curious what it can do.
View attachment 3389081
View attachment 3389083

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Does the CXB do better? It looks like it does just to compare the data sheets.

Flux(lm) is 14,340 for DB bin in CXB

Yes it would be a nice boost, but for some reason Cree only released warm whites in CXB so far.

So this heatsink here is rated at 0.67°C/W and can supposedly passively cool a CXA3070. This here is rated at 0.83°C/W (for a single piece with no fan). Does anyone think it would be good enough to passively cool a CXA3070 at 1.4a? Where it would sit in my cabinet will actually be at the same level as the fans so there will be some air flow anyway to help with cooling but yea..

Snapper said:

So this heatsink here is rated at 0.67°C/W and can supposedly passively cool a CXA3070. This here is rated at 0.83°C/W (for a single piece with no fan). Does anyone think it would be good enough to passively cool a CXA3070 at 1.4a? Where it would sit in my cabinet will actually be at the same level as the fans so there will be some air flow anyway to help with cooling but yea..

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The radial star sink would be good, but 20 bucks is just so expensive for 1 sink, and it would get pretty warm if you drove it at 1.4A or even 1.05A I'm guessing. The other option 27 bucks for that thing is absurd. Are you not in the US? You could get something so much better and cheaper from heatsinkusa.

I'm not in the US unfortunately, shipping is expensive to where I am. This was another option but the description thermal resistance is different than what's listed under specs so I'd need to check

Snapper said:

I'm not in the US unfortunately, shipping is expensive to where I am. This was another option but the description thermal resistance is different than what's listed under specs so I'd need to check

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If you're in Europe, refer to this thread.

Which heatsink do you guys think would be better for 140 watts of Vero29 actively cooled with a 140mm fan?

7.280"x14"

or

5.886"x20"

I like the 5.886" profile because the fan would cover most if not all of the fins, but the 7.280" has a thicker baseplate and is slightly heavier overall.

Not sure which one to choose.

The 5.88 will get more benefit from the fan, 400cm² more surface area, cheaper, more even heat load and better spread.

SupraSPL said:

Yes it would be a nice boost, but for some reason Cree only released warm whites in CXB so far.

Click to expand...

Update, I see some cool white CXBs at Cutter

Ready to order the heatsink for my second build but Im torn between the 5.375 and the 7.280. They will be 20" (x4) and have 2 cxb3590's @ 1.4 on each. Thats about 100 watts. Im worried that the 5.375 fins are too close and the 7.280 being to wide and further from the heat source.

The sinks will be mounted on upper part of a cabinet and air will have to pass over the top where the fins are to exit out of the cab and fins are inline with airflow. (sorta like its ducted) But there will be no fan laying directly on the sink.

Here is a side view of cabinet. There are 4 80mm fans across the back of cab lined up with each heatsink.

Im almost done with my first cabinet set up the exact same way except Im running 10 cxb3070 @ 1050 and 5 20" pieces of the 5.886 but only 60 watts on each piece there.

So anybody have an idea which profile to go with for the 50 watt 3590s?

That nice. Will you be putting sides on it, to make a full channel against the roof?

The main thing here is your sink won't shed heat evenly. The end near the fan will be hotter, since it only gets the hotter air for cooling....if you are completely ducted.

Else, if no duct, the fan end is the fan end is the coolest since is has direct source of cooler air, and doesn't have to pull along the length except slightly. The end without the fan will be hotter.

And did you say the back has 4 fans ACROSS the heat sink???

I would have those in the top firing down INTO the sink.

Yes. It will be a full channel. The only way for air to get by is the 3"x48" opening in front of the light.

Here is some pics of the start of my first cab that Im working on at the moment.

The heat sinks will be connected with thin ply between to form the channel. (and angles will be flipped over so they dont block flow)
This one has 5x 80mm 35cfm fans that will go in the holes drilled and the heat sinks will line up with them. So it will be 175 CFM passing over the top channel.

The back edge of the light will be hinged so I can drop the front down for cleaning inbetween runs.

So the 5.375 or 7.280 for the next?