Going commercial

ttystikk

ttystikk

Well-Known Member
OLD MOTHER SATIVA said:
i think its too tech for me



but is AREA " just" the factor and if my heat sync had fins and "mass.." ie. depth not just sq cm's..would that not allow me to use
a smaller area?

like a thicker, 10 circular finned highbay:

i am trying so hard[not hard] to "not" sound like i know anything

but using just sq # of sq cm does not compute..what about thermal mass and yes the fins have sq cm's too

forget me i am in too deep..lol
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You're correct there is a calculation that includes the fins. You'll find these formulas in the heat sink section of the LED forum.

Yes, I won't bullshit you, it will get fairly technical. Running chips at high watts without the use of cooling fans is not easy and definitely not recommended for those unfamiliar with the technology. See 'thermal runaway.' Running lots of chips nice and soft is much more practical and accessible, but it's substantially more expensive due to the large number of chips purchased.

And because I'm an engineer by trade, I can tell you that having someone REAL to talk to if warranty issues ever arise is well worth paying extra for! That feature in and of itself helps guarantee that things will be built right in the first place, if you think about it.

One very good reason to go with a panel like TastyLED is that all of these factors have already been solved for you. Just mount it at the proper height, plug it in and grow.
 
Rahz

Rahz

Well-Known Member
Thermal requirement calculations can get pretty complicated, at least to me. The mass does factor in but surface area is the most important variable.

The 12" profile at HSUSA is about 554 sq/cm per inch. If you wanted to run a CXB 3590 passive on it at 2.1 amps that would be 9 inches. You could use a bit less and still stay within Cree's suggested temps.

Radials do change the situation and require less material/surface area, but finding radial heatsinks ready to use with these chips is difficult at a reasonable price. I have built a lamp using passive radials but they are dissipating about 19 watts of heat each and running 65C. You can find them on ebay and get them in bulk for around $13 each which comes out to a little over $16 per pound. My lamp is 720 watt output (about 450 watts of heat), 17 lbs of heat sink alone and it's not enough. To get low 40s using the straight fin sinks would require about 55 lbs. of heat sink. I have another lamp (2nd attempt) using the same radials. They are dissipating about 12-13 watts of heat each and do keep the cobs in the low 40s. That lamp is just over 10 lbs of radial sinks and 350 watts/190 watts of heat.

Whether you build or buy I would consider using fans. Good ones are rated for 70,000 hours, about the same as the cobs.

For passive if you were to do 2 CXB3590s at 2.1 amps on 18" pieces of the 12" profile I think you would be happy with it. The sinks would cost as much as the cobs. Looking at it this way it is worth it to pay more for the radials by weight, but as far as a recommendation for something putting out that much heat I don't know how to help. If you wanted to run a bunch of CXBs at .7 amps each and put them on the radials I mentioned I think that would work out great too. You can find them by doing a search on ebay for "50W Watt LED Aluminum Heatsink Round". They can't dissipate 50 watts of heat and could barely handle 50w of output and would run very hot, but with the CXB3590 putting off about 9 watts of heat at .7 amps they would be a good match. You can also find 100W versions of the same heat sink. I imagine they would work well with CXB3590 at 1.05 amps.

However you look at it passive is going to cost more and be a heavier end product.
 
BiG PuFFer

BiG PuFFer

Well-Known Member
ttystikk said:
Lol this IS @Rahz 's thread about his LED panel building company... TASTY LED!

I'd say if anyone has any questions about his product lineup, here is the very best place to ask him.

I went with a custom builder for my panels because I had some specific needs to fill, but the chips and drivers I'm using are the same as Tasty's or equivalent (I'm running Meanwell drivers, not sure if this is the exact same or not). Johnson Grow Lights also uses the same chips from Cree and same/similar drivers. He's also on RIU, has his own forum, so it would be appropriate to discuss his equipment there instead of on the competition's thread. Just lookin' out for everybody.

If the panel comes from China, frankly I'm not interested.
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Im not looking for people to sell me on there lights. I just want the best light posable for the area and money amd im done with hid's. This whole tread area is diy or someone tring to sell you there product.
 
BiG PuFFer

BiG PuFFer

Well-Known Member
I see alot of specs on these cob lights where are the buds were are the plants? Anyone not affiliated with the manufacturer having success with these?
 
bassman999

bassman999

Well-Known Member
Rahz said:
A general rule of thumb is 120 sq/cm per watt for a passive design. This is based on heat dissipated. You can determine that by using the efficiency of the cob at your chosen drive current. A CXB3590 for example at 2.1 amps will produce about 39 watts of heat and need 4680 sq/cm of heat sink surface to keep temps down in the 40s.
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Maybe my math is wrong, but with that passive hs info I get a 26x28" hs to dissipate 39 watts?
s it cubic cm?
I am probably doing it wrong
 
Rahz

Rahz

Well-Known Member
bassman999 said:
Maybe my math is wrong, but with that passive hs info I get a 26x28" hs to dissipate 39 watts?
s it cubic cm?
I am probably doing it wrong
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The way I do it is to measure the profile (base x 2) + (fin height x 2 x number of fins). This gives sq/in per inch of heat sink material. To convert to sq/cm multiply by 6.45.

For the 12" profile (12 x 2) + (1 x 2 x 31) = 24 + 62 = 86 x 6.45 = 554.7 sq/cm. Divided by 120 is 4.6 watts of heat per inch. 39 watts would need 8.5 inches of that profile. which is 731 sq/inches... which is the same as 26x28". I don't know how you came up with that but you are correct. :)
 
littlejacob

littlejacob

Well-Known Member
BiG PuFFer said:
I see alot of specs on these cob lights where are the buds were are the plants? Anyone not affiliated with the manufacturer having success with these?
Click to expand...
Bonjour
Noone here except the one who open this thread is from a company...
Did you read the thread title?
Cxb are the best buy of my growers life!
It is incredible (cxb 3590! ) night and day compare to hid...
When I will have only cxb...soon...very soon...as soon as I can...I will throw my mh and hps FOR EVER!
I was like you few months ago...and people I don't know told me the same thing...I was skeptical...now I don't know how to thank them...I am so happy...gpw++ is at everybody's hands...gpw is a minimum with cxb...I am sure 2gpw in hydro is doable!
Have a great day ★
 
chipper68

chipper68

Member
littlejacob said:
Bonjour
Cxb are the best buy of my growers life!
It is incredible (cxb 3590! ) night and day compare to hid...
When I will have only cxb...soon...very soon...as soon as I can...I will throw my mh and hps FOR EVER!
I was like you few months ago...and people I don't know told me the same thing...I was skeptical...now I don't know how to thank them...I am so happy...gpw++ is at everybody's hands...gpw is a minimum with cxb...I am sure 2gpw in hydro is doable!
Have a great day ★
Click to expand...
Not getting in the commercial part (snipped) but I hope to be as enthusiastic as you! The HID's are effective, but a pain in the butt to deal with. I'm hoping to do the same thing, toss the HID as far as I can, as soon as I can!

Cheers!
 
bassman999

bassman999

Well-Known Member
My current grow is CXA but so far I have so little heat that I have to supplement heat in tent.
I am running 234W in 2x4 tent.
I reversed exhaust to blow on lights and exhaust from bottom just to get tent canopy to 77F
Hps even in winter I used a 700 cfm fan to exhaust, now 200cfm fan to keep air fresh
 
Positivity

Positivity

Well-Known Member
bassman999 said:
My current grow is CXA but so far I have so little heat that I have to supplement heat in tent.
I am running 234W in 2x4 tent.
I reversed exhaust to blow on lights and exhaust from bottom just to get tent canopy to 77F
Hps even in winter I used a 700 cfm fan to exhaust, now 200cfm fan to keep air fresh
Click to expand...

Put a few veros on small passive sinks and place it around the perimeter. Heater that makes 140+ l/w..lol
 
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