COB passive heatsink links/ Advice 20W per Cob 700ma

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crazyhaze1

Well-Known Member
I am looking to source some COB heatsinks . I am ordering some vero 18s to add to my current fixture so I can drive them lower current.

I am looking for some good bang for your buck heatsinks , I am only going to be driving at 700mA a COB ( 20W) per cob .
 
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crazyhaze1

Well-Known Member
I have EB strips running 700ma , mounted onto 3”x48”x1/8” aluminum flat bar. 81 watts of strip per Flat and it doesn’t get too hot .

Since I’m running this COBs at 20watts each could I get away with mounting 4 of these on Aluminum Flat of similar size as my last build ?

That would be 80watts if power over the same sized aluminum strip.

Does my thinking sound flawed or ? Advice plz .
 
whytewidow

whytewidow

Well-Known Member
crazyhaze1 said:
I have EB strips running 700ma , mounted onto 3”x48”x1/8” aluminum flat bar. 81 watts of strip per Flat and it doesn’t get too hot .

Since I’m running this COBs at 20watts each could I get away with mounting 4 of these on Aluminum Flat of similar size as my last build ?

That would be 80watts if power over the same sized aluminum strip.

Does my thinking sound flawed or ? Advice plz .
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I would say no. Bc the strips have smaller and spaced out diodes. To help dissipate heat easier. As where the cob all diodes are packed into smaller area. Which doesnt let the heat dissipate as fast bc the diodes are right next to each other. You can get cheap PC heat sinks on Ebay for a few bucks. With a fan.

I got these for 8 bucks for the pair shipped. And I run them at 900mA @36.05vdc at 32.xxx watts each. And they stayed extremely cool. They are older cobs. Cxa3050 in 4k.
mir_20181227_190253.jpg mir_20181227_190301.jpg mir_20181227_190311.jpg mir_20181227_190320.jpg
 
whytewidow

whytewidow

Well-Known Member
I mean you can run strips free air no heatsink at all. I dont know of any cobs that you can run free air. Even driven super low. I've since replaced the cobs with more strips. Why do you wanna add cobs why not more strips?
 
crimsonecho

crimsonecho

Well-Known Member
This is my diy. Cxb 1830s running at 700ma. 6 per heatsink. They are 1000mm x 190mm and 1.2 cm thick (less than half inches). When the tent is closed and there is a good air circulation the spots right behind each cob gets to about 25 C. When i open the tent and start working on the plants i need to turn of the fans and they get a bit hotter, like 45 degrees but doesn’t go over that.
 

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crazyhaze1

Well-Known Member
whytewidow said:
I mean you can run strips free air no heatsink at all. I dont know of any cobs that you can run free air. Even driven super low. I've since replaced the cobs with more strips. Why do you wanna add cobs why not more strips?
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My strip build is my veg light . I’m trying to have a more disperse flower fixture . I currently am driving vero29s hard with fans and can’t put it in a tent in case a fan ever died .

Also if I have a cob die , the extra amperage won’t be enough to damage my system this way .
 
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crazyhaze1

Well-Known Member
whytewidow said:
I would say no. Bc the strips have smaller and spaced out diodes. To help dissipate heat easier. As where the cob all diodes are packed into smaller area. Which doesnt let the heat dissipate as fast bc the diodes are right next to each other. You can get cheap PC heat sinks on Ebay for a few bucks. With a fan.

I got these for 8 bucks for the pair shipped. And I run them at 900mA @36.05vdc at 32.xxx watts each. And they stayed extremely cool. They are older cobs. Cxa3050 in 4k.
View attachment 4255785 View attachment 4255786 View attachment 4255787 View attachment 4255789
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These are awesome , I’m interested forsure! I wouldn’t run the fans on , realistically I would need about 10w heat dissipation max .
 
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crazyhaze1

Well-Known Member
crimsonecho said:
This is my diy. Cxb 1830s running at 700ma. 6 per heatsink. They are 1000mm x 190mm and 1.2 cm thick (less than half inches). When the tent is closed and there is a good air circulation the spots right behind each cob gets to about 25 C. When i open the tent and start working on the plants i need to turn of the fans and they get a bit hotter, like 45 degrees but doesn’t go over that.
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Thanks man, that’s a good comparison to what I wanna do. My strips end up pretty much that temp with no fans . I’ll see if I can get some Flats a quarter thick, they are really cheap where I live .

How many watts are on each flat of yours ?
 
crimsonecho

crimsonecho

Well-Known Member
crazyhaze1 said:
Thanks man, that’s a good comparison to what I wanna do. My strips end up pretty much that temp with no fans . I’ll see if I can get some Flats a quarter thick, they are really cheap where I live .

How many watts are on each flat of yours ?
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Thats 175w per heatsink. If you have the option i would suggest 1 inch thick or around there somewhere to keep it even cooler. Thats my personal advice on a setup like this. Even tho half inches does the job, as i said, when the draft stops for any reason they get hotter than i like them to be.

Or 2 small fans on each heatsink could do the job too and the diodes will not burn even if the fans malfunction.
 
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crazyhaze1

Well-Known Member
crimsonecho said:
Thats 175w per heatsink. If you have the option i would suggest 1 inch thick or around there somewhere to keep it even cooler. Thats my personal advice on a setup like this. Even tho half inches does the job, as i said, when the draft stops for any reason they get hotter than i like them to be.

Or 2 small fans on each heatsink could do the job too and the diodes will not burn even if the fans malfunction.
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Sounds good ! Thanks . I can get most sizes . Lots of skilled trades and metal suppliers here .
 
Rahz

Rahz

Well-Known Member
You can get the benefits of fan cooling while creating a fail safe situation using around 100sq/cm per heat watt and fan cooling it. I've done this with 16" pieces of the 5.886 profile from HSUSA cooling 2 50w cobs. Fans push the case temp to low 40s and if the fan goes bad it's no problem.

Splurge on the aluminum. 10 years from now you'll be using the same sinks and smiling about it.

A 5" piece of the 5.886 profile = 1290 sq/cm of surface area. Enough to dissipate 11 watts of heat passively. 10 bucks plus shipping. Or go overkill and pay a little more for some 133mm pin fin sinks from cobkits.
 
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crazyhaze1

Well-Known Member
Rahz said:
You can get the benefits of fan cooling while creating a fail safe situation using around 100sq/cm per heat watt and fan cooling it. I've done this with 16" pieces of the 5.886 profile from HSUSA cooling 2 50w cobs. Fans push the case temp to low 40s and if the fan goes bad it's no problem.

Splurge on the aluminum. 10 years from now you'll be using the same sinks and smiling about it.

A 5" piece of the 5.886 profile = 1290 sq/cm of surface area. Enough to dissipate 11 watts of heat passively. 10 bucks plus shipping. Or go overkill and pay a little more for some 133mm pin fin sinks from cobkits.
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Thanks! These numbers will reallly help me .
 
whytewidow

whytewidow

Well-Known Member
crazyhaze1 said:
My strip build is my veg light . I’m trying to have a more disperse flower fixture . I currently am driving vero29s hard with fans and can’t put it in a tent in case a fan ever died .

Also if I have a cob die , the extra amperage won’t be enough to damage my system this way .
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Gotcha. Cant go wrong with strips tho lol. You can lay your face on the diodes. Frame/heatsink cost me 16 bucks.
20181227_220343.jpg
 
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crazyhaze1

Well-Known Member
whytewidow said:
Gotcha. Cant go wrong with strips tho lol. You can lay your face on the diodes. Frame/heatsink cost me 16 bucks.
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This is sweet ! I also built a dual spectrum light :) how do you like yours? I just started using mine last week. The heatsink run a bit to hot to put my face on since I crammed so many on. Hot to the touch if I leave my hand on for too long but not bad by any means . My lightbulbs get hotter :p
 

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whytewidow

whytewidow

Well-Known Member
crazyhaze1 said:
This is sweet ! I also built a dual spectrum light :) how do you like yours? I just started using mine last week. The heatsink run a bit to hot to put my face on since I crammed so many on. Hot to the touch if I leave my hand on for too long but not bad by any means . My lightbulbs get hotter :p
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I love the strips a ton man. I built one awhile back. 10 f562b strips in 3k pushed by a hlg320h24b. (5) 96 diode sunboards in 27k pushed by a hlg240h24a and (4) custom made copper pcb 120 diodes 60 of each He photo red and deep red. Alternated in the pcb. Being pushed by a LPV-60-24. And I liked so much built for flower only. But it does so well I built the one I posted above. It has (3) fb562b in 3k driven by hlg120h24a (4) f562b in 4k driven by hlg-150h-24b and (6) H inFlux_L06 in 4k driven by hlg240h24a. But I'm getting ready to yank the big one out to revamp it a lil. Adding 2 more f562b 3k strips to bring down the current a little. And adding 1 more 27k sunboard. Bc they are being driven hard at 2.0A each. So adding another will bring it down to 1666mA each. Max is 2.5a with really good sinking. I used 2x2 thick walled extruded aluminum tubing. Cut 3 sides of it. Every inch. And mounted the strip on the uncut side. And put PC fans on one end of the tubing to blow through it. It's super heavy and a pain in the ass to adjust. Or get in n outta the tent. So I'm pulling it. Rebuilding the frame with just U channel to lighten it up. And adding the strips. I'm pulling just over 6 zips per 2gal pots. I'm hoping lightening it up so I can adjust height better and adding the strips will make it more efficient. And hoping to hit 7 zips per 2gals.

First one I built below. You can see in the bottom pic how I cut the 2x2 tubing. When the PC fans arent running the slots let heat escape so it doesnt have to travel the length of the tube. I mounted a sonoff control temp sensor on the inside against back of the flat part the strip is on. And set temp points on the app. So the fans only run when it hits a certain temp. Then they shut off when they cool down enough.
20181211_213527.jpg

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crazyhaze1

Well-Known Member
whytewidow said:
I love the strips a ton man. I built one awhile back. 10 f562b strips in 3k pushed by a hlg320h24b. (5) 96 diode sunboards in 27k pushed by a hlg240h24a and (4) custom made copper pcb 120 diodes 60 of each He photo red and deep red. Alternated in the pcb. Being pushed by a LPV-60-24. And I liked so much built for flower only. But it does so well I built the one I posted above. It has (3) fb562b in 3k driven by hlg120h24a (4) f562b in 4k driven by hlg-150h-24b and (6) H inFlux_L06 in 4k driven by hlg240h24a. But I'm getting ready to yank the big one out to revamp it a lil. Adding 2 more f562b 3k strips to bring down the current a little. And adding 1 more 27k sunboard. Bc they are being driven hard at 2.0A each. So adding another will bring it down to 1666mA each. Max is 2.5a with really good sinking. I used 2x2 thick walled extruded aluminum tubing. Cut 3 sides of it. Every inch. And mounted the strip on the uncut side. And put PC fans on one end of the tubing to blow through it. It's super heavy and a pain in the ass to adjust. Or get in n outta the tent. So I'm pulling it. Rebuilding the frame with just U channel to lighten it up. And adding the strips. I'm pulling just over 6 zips per 2gal pots. I'm hoping lightening it up so I can adjust height better and adding the strips will make it more efficient. And hoping to hit 7 zips per 2gals.

First one I built below. You can see in the bottom pic how I cut the 2x2 tubing. When the PC fans arent running the slots let heat escape so it doesnt have to travel the length of the tube. I mounted a sonoff control temp sensor on the inside against back of the flat part the strip is on. And set temp points on the app. So the fans only run when it hits a certain temp. Then they shut off when they cool down enough.
View attachment 4255922

View attachment 4255923
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Holy shit I think I just found my new best friend haha . Your settup is so good ! Would you say nothing over 4000k for a flower lamp?


currently half my cobs for my end fixture are in 3500k from the cobs I have now , how would you spread out the light spectrum for the remaining half I need to buy?

24 COBs over a 4x4 will have to be my end fixture between 2 Drivers (37.5w per sq ft ). Gonna spread the light perfectly for the tent I’m buying . I’m over killing the tent a bit buying a 6x6 since the cost is not much different and I like room to move around :) .
 

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Rocket Soul

Rocket Soul

Well-Known Member
crazyhaze1 said:
I am looking to source some COB heatsinks . I am ordering some vero 18s to add to my current fixture so I can drive them lower current.

I am looking for some good bang for your buck heatsinks , I am only going to be driving at 700mA a COB ( 20W) per cob .
Click to expand...
We have a nice and cheap alu shop around here. We build heatsinks by getting a wide u-channel extrusion and then glueing a smaller u-channel with tall wings on top of it. Id want at least 5-6 mm of of alu behind the centre of the cob for 20w operation. 10mm for 50w cob.
 
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