Heatsinks for DIY LED lamps

DoctorDelta9

DoctorDelta9

Well-Known Member
SupraSPL said:
So your 5.88" X 48" bar is 12500 cm², good for 167W passive cooling or 500W active cooling. So at 300W you are getting 41.6cm²/W which is very good for active cooling. Due to the length of the heatsink you might benefit from a shroud to keep the airflow in the channels. Even if you only went a foot from the center with the shroud it would help guide the airflow and the heatsink would still have the ability to cool itself in the case of a fan failure.

Because this setup gives you excess cooling power, you could use a slimmer profile such as the 4.9" (11300 cm²) (should be back in stock may 8th). It has a thicker base plate than the 5.88, which may benefit you since you will have an uneven heat load. On the other hand maybe the extra surface area of the 5.88" would make up for it. Same cost either way and with either choice you will get awesome performance

CXB3590 3K CB X 12 = 906W dissipation or 413 PAR W. I would recommend reflectors or lenses because of the distance to canopy. If you use the 50mm 90 degree lens, 372 PAR W or 14.9 PAR W/ft². That is about 742 PPFD average, very good intensity and awesome bud potential :)
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I already ordered the 80deg lenses. I plan on making the "light bars" height adjustable. What is my optimal distance from light to canopy? My only worry about covering the ends of the sinks is heat retention over those outer lights. I'm sure it won't be much because they will be actively cooled, however I want the fail-safe just in case my fans die :roll:. I suppose some alum. Sheet metal would work best for this purpose. Now the question remains. One fan per bar or two. I've read about fans fighting for air. But these suckers are so long that im pretty sure I will require 2 per bar. Also.....I had a thought. What if I were to cover the entire length of the sink with alum sheet, creating channels. And have my fans pulling air instead of pushing. If I could suck that hot air right off the sink let if flow up with the natural convection and straight into my exhaust seems more efficient than trying to push hot air down.
As always thanks for chiming in guys! Much love!:bigjoint:
 
DoctorDelta9

DoctorDelta9

Well-Known Member
On another note,
I found a custom heatsink shop online that said they would beat HSusa price. They want me to send the a spec sheet.
So if we could design a 'perfect' (I use that term loosley) heatsink for our type of application, what would it be?
Fin height?
Fin spacing?
Fin width?
Baseplate width?
How awesome would it be to get a 48" x48" to hang above the lights and spread the cobs as efficiently as possible!!!
 
alesh

alesh

Well-Known Member
DoctorDelta9 said:
On another note,
I found a custom heatsink shop online that said they would beat HSusa price. They want me to send the a spec sheet.
So if we could design a 'perfect' (I use that term loosley) heatsink for our type of application, what would it be?
Fin height?
Fin spacing?
Fin width?
Baseplate width?
How awesome would it be to get a 48" x48" to hang above the lights and spread the cobs as efficiently as possible!!!
Click to expand...
Not sure about things you asked, but these are 2 awesome features for DIY-friendly heat sinks:
hs_fan.jpg
Easy fan mount (a standard 80mm fan can be mounted on this HS)


nodrill.jpg
Easy LED attachment - w/o the need for drilling and/or tapping holes.
 
EfficientWatt

EfficientWatt

Well-Known Member
Also has a thin base, and small distance between fins .. Definitely more suited for active cooling, as DocΔ9 pointed out.
 
DoctorDelta9

DoctorDelta9

Well-Known Member
SupraSPL said:
Finally got around to organizing this and I figured it might come in handy for those who are designing DIY lamps. These charts show the surface area and surface area/cost for each of the Heatsink USA profiles.
View attachment 3300177

So in summary, the cheapest surface area is the 2.08" profile. It gives a lot of spread, maybe too much spread for our purposes. The 4.85" is also cheap and might be good for a vegging heatsink. Thin base plate though, not ideal for COBs.

The 4.6" serrated is a good value and it has a .23" baseplate thickness/riser height so it might be good for COB and gives a good spread between COBs. It has decent height to the fins, so uses active cooling efficiently (120mm fan should cover all fins). The 4.9" has a thick.3" base plate and still gives a good spread, should be very good for high powered COBs. Same with the 5.88" and it fits 140mm fans.
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This needs to be pinned. I've already printed myself a hardcopy. Lol. @SupraSPL you sir are the man
 
Bueno Time

Bueno Time

Well-Known Member
Check this shit out some guy posted in my grow thread, figured I would share it over here.

DaBeaverFunk;6928399 said:
So I built a light w/ 6 Vero 10's per 44" of heatsink. The same profile you are using BT. I'm running them at 90watt, so less efficient than your setup but still much better then my previous attempts.

I did some CFD analysis on the heatsinks and ended u. Cutting some 20*C off their ambient temperature by slotting the heatsinks to increase airflow around the fins. I had access to a mill to do this, you may be able to get by with a dremel and a shit ton of patients.






6 vero 10's @15watts a piece x 3 bars.
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So these channels he cut out allow convection to pull cooler air through the fins from the bottom of the sinks and apparently its very effective with a 20*C drop in temp on a 2.08 x 44" bars running 90w each.

I love it! Wish I had access to a machine like this.
 
Positivity

Positivity

Well-Known Member
I love it....looks nice like that too..

Kinda surprised its cooler with less metal though. And the extra metal between cobs...makes me wonder if they are even conducting much heat?

But 20c less....its working!
 
SupraSPL

SupraSPL

Well-Known Member
Very interesting idea, although cutting off 20C would mean they were running super hot to begin with, ideally they should be at only a few degrees above ambient (maybe he wasnt shooting for Tj 50C). 44" should be good for 50W passive cooled. So even with the notches it sounds like they are still running hot.

I spose cutting away the base plates in between would not matter much as long as the heat load was balanced in each section. And at that point the fins just act as support for the most part.
 
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Bueno Time

Bueno Time

Well-Known Member
Yeah Im sure they were super hot with 90w on 44", I been running almost 1w per linear inch of 2.08 profile and its pretty warm to the touch as it is, passively cooled.
 
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