Heatsinks for DIY LED lamps

[organic-fanatic]

Bonjour
18X80...inches...cm...?
And why 18x80 and not 50x50 or a square?
If it is inches you will need more watt per plant if it is cm less...
Have a great day ★

Inches, thats the size that works for what i want to do with the space i have. Essentially turning 1 room into 6. To run a no-till 3wk 5 strain perpetual harvest with diy led. Theres alot to it and im not sure this is the thread to do it in but i want to answer & thank you for your advice.
@stephen thank you, @ttystikk , sounds like a good idea to start a thread. When i figure out how, and the ladies finish hanging in that space. Prob a month out.

 

[ttystikk]

Inches, thats the size that works for what i want to do with the space i have. Essentially turning 1 room into 6. To run a no-till 3wk 5 strain perpetual harvest with diy led. Theres alot to it and im not sure this is the thread to do it in but i want to answer & thank you for your advice.
@stephen thank you, @ttystikk , sounds like a good idea to start a thread. When i figure out how, and the ladies finish hanging in that space. Prob a month out.

Tag me as soon as you get going, I want to see it! I happen to have a few friends with limited mobility and I'm always looking for tips.

 

[Stephenj37826]

Tag me as soon as you get going, I want to see it! I happen to have a few friends with limited mobility and I'm always looking for tips.

Tag me as well. I'm glad to help anyway I can.

 

[SupraSPL]

Was just digging through HeatsinkUSAs specs. Interesting that some of the profiles are made from 6063-T5 and some are 6063-T6. Looks like the T6 is a stronger material by weight but the T5 has slight better thermal conductivity:

6063-T5 = 210 W/m-K
6063-T6 = 200 W/m-K

I don't think this affects us in any way but maybe useful to know the conductivity we are working with.

 

[SLITLOS]

Was just digging through HeatsinkUSAs specs. Interesting that some of the profiles are made from 6063-T5 and some are 6063-T6. Looks like the T6 is a stronger material by weight but the T5 has slight better thermal conductivity:

6063-T5 = 210 W/m-K
6063-T6 = 200 W/m-K

I don't think this affects us in any way but maybe useful to know the conductivity we are working with.

The T scale has to do with hardness, you can take "O" and heat treat it to higher T hardness or T6 and anneal to a lower T number. I use to anneal T3 to O and run the metal through a
drop hammer making the part and and work hardening it back
to T3. Mostly it's the heat treating that make the T level.
In you case, the 6063 is all the same, the structure(grain) of the metal is stronger.
When the metal is HOT and being shit out of the forming die's,
it's in the O condition and will age harden to the higher T #.
SLITLOS

 

[doz]

For some reason, I am just not grasping the concept of what is needed in a heatsink. I am trying to figure out passive cooling for my next build. I have a feeling I am missing something. What exactly is the formula to figure this out? I will be utilizing CXB3590 running @ 50w each, 56% efficiency.

What I have read is I will need 120cm^2 per watt of heat, which should be 22w.

120x22 = 2640 cm^2 of surface area per cob. Is that correct?

That would mean I would need a 41"x10" heatsink just to cool one cob which I know is not right. So where am I going wrong? I know I am missing something.

41"x10" heatsink is 2645 cm^2 (to get CM^2 I am using the formula of IN^2/.155 which is the same as 6.45 CM^2 x In^2).

@SupraSPL

 

[Jerry Liebler]

I really want passive cooling in the lights I'm planning. It now looks like I'll be using vero 18's, putting 6 of them per lamp with an HGL-185H-C1050B.I found these and might adapt them. http://www.aliexpress.com/item/2pcs-40W-50W-LED-Heat-Sink-D122mm-H27mm-Aluminum-Profile-Radiator-Cooler-For-30W-40W-50W/32406290852.html
If they work for other lighting, I'd hope they'll work with the Veros. To adapt them I'd make up mounting plates that would sit between the profile and the COB probably made of 1/8" aluminum. It's probably overkill but copper is also a candidate. Any opinions/guess at thermal resistance of these?

 

[Rahz]

Surface area includes the fins so the length required will depend on the profile, number and height of fins. Much less than 41x10

For some reason, I am just not grasping the concept of what is needed in a heatsink. I am trying to figure out passive cooling for my next build. I have a feeling I am missing something. What exactly is the formula to figure this out? I will be utilizing CXB3590 running @ 50w each, 56% efficiency.

What I have read is I will need 120cm^2 per watt of heat, which should be 22w.

120x22 = 2640 cm^2 of surface area per cob. Is that correct?

That would mean I would need a 41"x10" heatsink just to cool one cob which I know is not right. So where am I going wrong? I know I am missing something.

41"x10" heatsink is 2645 cm^2 (to get CM^2 I am using the formula of IN^2/.155 which is the same as 6.45 CM^2 x In^2).

@SupraSPL

 

[doz]

Thanks Rahz. I figured I was missing something. Thats a big miss

Surface area includes the fins so the length required will depend on the profile, number and height of fins. Much less than 41x10

 

[SupraSPL]

@doz You have the surface area requirement correct for passive, 2645cm² per COB in this case. If you used a 10" X 6" that would give you 2850cm².

 

[sureshot138]

I went with the 10"x6" for my 3590's at 1.4a. I don't have them in my tent yet but last night I had it on for an hour in a room with little to none air movement I could but my hand on top of the sinkright above the cob for about 15 to 20 seconds before it got too hot. I but a small 80mm PC fan blowing on them and it never got to hot to put your hand on. I think with the fans in the tent this will work great.

 

[Will Thayer]

Hello Friends,
This seems like good thread to post my query. I have a plan in the works (big thanks to all who have helped me) I have 6x 1000mm by 150mm heatsinks which I intend to shroud and actively cool with 140mm fans one per sink. Each sink will have 4x CXB3590 run @700ma (23w). Am I right in thinking total watts minus 64% give me the heat wattage? I am trying to calculate how much heat (in wattage and then converted to BTU maybe?) 24 CXB3590 @700ma will add to the grow room.
I am toying with the idea of running a sealed or perhaps semi sealed room in the winter months. I already have a programmable dehumidifier, water cooled co2 generator (with option to run uncooled in winter) with sensor/controller. I have one carbon filter hooked as exhaust with backdraft shutter if I need to vent outside the space and a separate carbon filter for just scrubbing the room internally. If the heat output is negligible perhaps I could run the room in the summer time with the exhaust fan to outside the room on temp/humidistat.
Any assistance with the mathematical calculations would be received with much appreciation.

Cheers,
Will

 

[littlejacob]

Bonjour
Hi my friend!
You could put 8 cxb 3590 @24w on this hs and put 2 140mm fans...no problem I guess!
CU

 

[Quintrix]

Hi!!!!!! wow another super post at RIU !!!! I'm reading a lot about it and still not sure if the dissipation is a function of the heat sink measures (perimeter x length) or if you have in mind some other factor.
I found this http://www.tme.eu/es/details/rad-a4291_1000/disipadores/ heatsink in Europe at a good price, Could mount 3 or 4 cxb3590cd @ 1400mA (50w) in one of these of 32inchs long passively?
thanks guys, very good job here !!!!!!!

 

[Jerry Liebler]

I spent some more time on aliexpress and found these:
http://www.aliexpress.com/item/Free-Shipping-2-pieces-50w-Pure-aluminium-heat-sink-for-led-lamp-cooling-DIY-Led-Light/32510221467.html
I sure would like to know the thermal resistance.
The price is reasonable so I ordered some. I have a collection of hole saws and some 1/8" aluminum so I'll make a plate for the center, mount a 25 watt resistor on it, hang one up, power the resistor from a "lab" supply and measure the temperature, at the resistor and ambient with my 2 channel thermometer. Meanwhile a question for the experts here: What is the heat output of a Vero 18, 5000K, CRI 70 running 30W input? Also a Vero18, 2700K CRI 80?

 

[littlejacob]

Hi!!!!!! wow another super post at RIU !!!! I'm reading a lot about it and still not sure if the dissipation is a function of the heat sink measures (perimeter x length) or if you have in mind some other factor.
I found this http://www.tme.eu/es/details/rad-a4291_1000/disipadores/ heatsink in Europe at a good price, Could mount 3 or 4 cxb3590cd @ 1400mA (50w) in one of these of 32inchs long passively?
thanks guys, very good job here !!!!!!!

Bonjour
Are you talking about the 1000X165X35mm aluminum radiator from tme? (36.50 €...43 € vat included!)
If it is this one I split this one in 4 part with cxb 3590@1400mA on each...it gets hot so if you let it like it is and don't split it you will need a 140mm fan or 4 x80mm! Plus a 50mm for the driver!
Have a great day ★

 

[ttystikk]

I spent some more time on aliexpress and found these:
http://www.aliexpress.com/item/Free-Shipping-2-pieces-50w-Pure-aluminium-heat-sink-for-led-lamp-cooling-DIY-Led-Light/32510221467.html
I sure would like to know the thermal resistance.
The price is reasonable so I ordered some. I have a collection of hole saws and some 1/8" aluminum so I'll make a plate for the center, mount a 25 watt resistor on it, hang one up, power the resistor from a "lab" supply and measure the temperature, at the resistor and ambient with my 2 channel thermometer. Meanwhile a question for the experts here: What is the heat output of a Vero 18, 5000K, CRI 70 running 30W input? Also a Vero18, 2700K CRI 80?

Heat input, 30W. Heat output, 30W. All the cob does is change the form of some of it.

 

[Jerry Liebler]

"Heat input, 30W. Heat output, 30W. All the cob does is change the form of some of it."
But some, hopefully most, of the "heat" output is in the form of light that goes to the plants. Whatever goes out as light doesn't have to be dealt with thermally in a heat sink. My question is how much must the heat sink "handle".

 

[ttystikk]

"Heat input, 30W. Heat output, 30W. All the cob does is change the form of some of it."
But some, hopefully most, of the "heat" output is in the form of light that goes to the plants. Whatever goes out as light doesn't have to be dealt with thermally in a heat sink. My question is how much must the heat sink "handle".

You asked about heat output. The light coming from the unit turns into heat the moment it lands on something. The point I'm making is that you'd do well to plan for the removal of every watt of heat the chip produces.

 

[doz]

Well just as reference, I tested my 2 lights. I typically run them with a 240mm fan http://www.amazon.com/Cooler-Master-MegaFlow-200-Computer/dp/B008G3OLRQ/ref=sr_1_1?ie=UTF8&qid=1447008745&sr=8-1&keywords=240mm fan and they stay cool to the touch. They are 18x10 (10" profile) from HeatsinkUSA with 4x CXB3070 cob pushed @ 50w each (200w total). While I understand the requirements for passive, I wanted to see how hot it would really get.

After leaving them on for about 30 minutes (no more rise), the light with the fan off got quite hot. The heatsink in the center (furthest point but equal from all 4 COBS) was getting up to 43c while the one with the fan running was sitting at 29c. I really want to to passive cooled, but I am a huge believer in keeping things cool to make them last. I understand that I would need about 28"x10" (100 sq in more surface area) to keep these cool passively but even then I am not so sure Id be comfortable.

After about 10 minutes of turning the fan back on, I was back down to 31c in the center. Keep in mind, this was just a test with no air blowing over the heatsink so in a real world environment with fans for the plants, it would probably be lower.

Maybe I will go passive with the 3590 and if I need to add a fan I can.