Heatsinks for DIY LED lamps
- Thread starter SupraSPL
- Start date
Well, it was a good bit hotter near the cobs. That 43c was towards the center and while fail safe it would be fine still I fully believe, I would not want to run it daily like that. With the infrared sensor I have, its a pain in the ass on the lights. It does not pick up the aluminum temperature very well. I sometimes have to put tape (the kapton is what I usually aim for) to pick up the real temp depending. Kinda weird.
But yes, I agree that I would be comfortable if a fan failed. I have no way to measure the output other than my kilawatt. I did not notice a drop in power draw, stayed consistent so it didnt seem to hit a temp wall (although I am sure the efficiency was down).
But yes, I agree that I would be comfortable if a fan failed. I have no way to measure the output other than my kilawatt. I did not notice a drop in power draw, stayed consistent so it didnt seem to hit a temp wall (although I am sure the efficiency was down).
Jerry Liebler
Member
After some more browsing the WWW I found:
http://www.led-heatsink.com/ModuLED_Modular_Passive_LED_Cooler.phtml
NO machining needed, just bolt on!
Lots of good choices. What is an acceptable temperature rise?
1.34 degree C/W costs $9.91, 0.88 degree C/W costs $14.85.
Even if the thermal power is the full 30 watts the chip temperature is under 70C. with the cheap solution.
http://www.led-heatsink.com/ModuLED_Modular_Passive_LED_Cooler.phtml
NO machining needed, just bolt on!
Lots of good choices. What is an acceptable temperature rise?
1.34 degree C/W costs $9.91, 0.88 degree C/W costs $14.85.
Even if the thermal power is the full 30 watts the chip temperature is under 70C. with the cheap solution.
Jerry Liebler
Member
From searching on this site I've learned: Passive cooled designs with a heat sink area of 110 CM2/W(thermal) will run at about a 10 degree C rise above ambient. The Vero 18 at test current dissipates about 60% of the energy supplied, stated another way is 40% efficient. A 29" length (chosen based on my planned spacing of 9.5") of the heat sink USA 4.9" profile ($51.62) will cool 3 Vero 18's (54 thermal watts) using the Supra recommendation. Good golly miss Molly that's a thermal resistance of 0.185 degree C/W! The commercial heat sinks are WAY WORSE at any price! 2 heat sinks and 1 driver makes a 180W lamp. 4 lamps to cover a 4 foot square (the center has no COB over it), about 45W/sq ft.
Jerry Liebler
Member
I found Supra's posts on actual testing and at 115CM2/W he had a 9C rise above ambient while at 90CM2/W he had 11C rise. I can switch to the 4.85 profile ($28.42) which would be 106CM2/W rather than the 124.8CM2/W that the 4.9 ($51.62) gives and still be under 10 degree C rise. But I'll stick with the 4.9 even though it's ultra conservative mainly because of the thicker base plate (0.3" vs 0.14"). I could even go to 1.4amps with the unavailable HLG-240H-C1400B.
Last edited:
Greengenes707
Well-Known Member
Jerry Liebler
Member
Well I'm glad I haven't ordered any parts yet because I'm not pleased with the efficiency and PAR output, mainly because of the Vero 18s. I'm now thinking of 16 Vero 29's instead of 24 Vero 18s to cover a 4 foot square. I'll still build 4 " fixtures" but each will cover a 2' x 2' square. Spacing the COBs 1' each way, 2 per 23" heat sink. The Vero 29 is 44.5%+ efficient at 1.4 amps so each heat sink deals with 56W. 23" of the 5.88 profile comes out 107cm2/w, a bargain at $40.02. Unfortunately the driver match is not as pretty with the Vero 29, until the HGL-240H-C1400B is available I'll use the HGL-120-C1400B to drive 2 cobs. Roughly $300 in material yields a 200W fixture that'll deliver 22.25 par watts /sq ft. Now I'm thinking of adding some red "stars" to shift the spectrum for flowering and use up some of the excess driver capacity. The drivers will allow addition of 20 red stars, maybe more, to each heat sink (2 parallel strings of 10, about 29.4W) but that's probably pushing the heat sink. What efficiency are red stars?
ttystikk
Well-Known Member
If efficiency is what you want, buy CXB3590 chips. The up front cost is only once and they'll save you power for as long as you use them.
Four of them driven at 50W and the 200W driver to power them will cost you less than $250. If you choose the 3500k CD bin chips, efficiency with this combination is 56%, for comparison purposes.
This combo is nearly twice as efficient as any HID lamps currently on the market, and this is certainly true after the second month of operation; lumen depreciation doesn't affect COB LED.
Jerry Liebler
Member
Switching to CXB3590 does save half the drivers as the HGL-185-C1400 can power 4. Does anyone stock these?
ttystikk
Well-Known Member
Jerry at kingbrite. Someone around here has contact info?
littlejacob
Well-Known Member
Quintrix
Active Member
but reference to estimates Supra
(4) CXB3590 3500K CD 36V @ 1.4A (49W ea)
(1) HLG-185H-C1400
196 dissipation W -> 85.7W heat ->
passive cooled heatsink 10284cm² -> 5.88" X 38" heatsink (could split in 2 to improve uniformity/spread)
It should not be worth?
Perimeter = 84cm (3cm 14fins 2 sides) + 34 (x2 base) = 118cm x 100cm perimeter length = 11800cm2 !!!! also it is larger than the recommended 5.88 Supra
thanks for answering,
ttystikk
Well-Known Member
I said only for COBs and driver! Thank you for completing the list of necessary components!
Quintrix
Active Member
42,5$ each cxb3590? great price, Jerry says me 47,5$, -5$ ea.
ttystikk
Well-Known Member
Quantity discount?
Growmau5
Well-Known Member
it could be a cultural difference. Perhaps Jerry is used to being negotiated with a little bit. he quoted me $46.50 each for what I considered a bulk order of 32 units. Maybe If I would have tried a bit harder, I could have saved $160....
littlejacob
Well-Known Member
Bonjour
Nope huys...he said that he talked with Cree and now the prices are lower...
It is in the newsletter from kb!
Go in kingbrite rocks thread!
Have a great day ★
Nope huys...he said that he talked with Cree and now the prices are lower...
It is in the newsletter from kb!
Go in kingbrite rocks thread!
Have a great day ★
Jerry Liebler
Member
If I'm going to "abandon" the Veros for CRE due to efficiency, the CXB3590 CD bin isn't the only choice, though it appears to be the most efficient. Perhaps The CXB 3070 BD bin is more price friendly & still offers great efficiency ( 54+%).
don benosee
Well-Known Member
I didn't know there was a newsletter?