DoctorDelta9
Well-Known Member
I'm sure everyone would be interested in seeing your plans. I know I would. Can you post some pics?
Heatsinks for DIY LED lamps
- Thread starter SupraSPL
- Start date
DoctorDelta9
Well-Known Member
What kind of LEDs?
100 w Chinese cob = $7 on eBay x 10 total . I'm only running 4 of them right now.
this is the plumbing and the back side of the water block. It's very rough just to test my theory on the effectiveness of the design. The bucket has a 640gph pump with 1 line in one line out. The one running out flows thru the combo of pex and vinyl to the block of aluminum and thru a channel under each cob. then out to a heater core with a fan that then flows back to the bucket.
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DoctorDelta9
Well-Known Member
Should be able to highlight copy, paste. Post a link to your other thread
salmonetin
Well-Known Member
...then... actively cool 1800 cm2.....1800 / 25 = 72 w
...semi pasive 1800 cm2......1800 / 55 = 32 w
...passive 1800 cm2.............1800 / 75 = 24 w
w = Vf x If ....for certain If correspond certain Vf ....
....for vero 18....
https://www.rollitup.org/t/all-things-vero.851330/page-2#post-11067863
from...supra too.... thanks supra...
...with w from vero 18... ....1 w actively cool = 25 cm2... 1 w semi pasive = 55 cm2 ....1 w passive = 75 cm2 ....
examples... ...+ o - ehhh.....
...1 vero 18 at 900 mA ...29 v .... 900 x 29 / 1000 = 26 w ....26 x 25 = 650 cm2 for one vero 18 at 900 mA...
...1 vero 18 at 1800 mA ... 31v ... 1800 x 31 / 1000 = 56 w ... 56 x 25 = 1400 cm2 for one vero 18 at 1800 mA...
saludos
...semi pasive 1800 cm2......1800 / 55 = 32 w
...passive 1800 cm2.............1800 / 75 = 24 w
w = Vf x If ....for certain If correspond certain Vf ....
....for vero 18....
https://www.rollitup.org/t/all-things-vero.851330/page-2#post-11067863
from...supra too.... thanks supra...
...with w from vero 18... ....1 w actively cool = 25 cm2... 1 w semi pasive = 55 cm2 ....1 w passive = 75 cm2 ....
examples... ...+ o - ehhh.....
...1 vero 18 at 900 mA ...29 v .... 900 x 29 / 1000 = 26 w ....26 x 25 = 650 cm2 for one vero 18 at 900 mA...
...1 vero 18 at 1800 mA ... 31v ... 1800 x 31 / 1000 = 56 w ... 56 x 25 = 1400 cm2 for one vero 18 at 1800 mA...
saludos
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bicit
Well-Known Member
Back from the abyss he rises again!...then... actively cool 1800 cm2.....1800 / 25 = 72 w
...semi pasive 1800 cm2......1800 / 55 = 32 w
...passive 1800 cm2.............1800 / 75 = 24 w
w = Vf x If ....for vero 8.... ....for certain If correspond certain Vf ....
from...supra too.... thanks supra...
https://www.rollitup.org/t/all-things-vero.851330/page-2#post-11067863
...with w from vero 18... ....1 w actively cool = 25 cm2... 1 w semi pasive = 55 cm2 ....1 w passive = 75 cm2 ....
saludos
Hi all,
I stopped growing a few years ago, but now I'm looking to get back into it with a somewhat stealthy 2 small plant grow in a 36"w x 42"h x 18"d metal cabinet in my garage. After reading the LED threads here, I'm sold on LED and want to build a combo veg and flower light.
I'm planning to do 3 Vero 29 3k at 500 - 1.050 ma for flower, and 2 Vero 18 5000k at 500 ma for veg on a single heatsink. The veg LEDs would max at 28 watts, flower LEDs would range between 53 to 114 depending on how hard I drive them. They should run pretty efficient too, at the lower ma. I'd run veg and flower LEDs separate, so the max watts at one time would be 114.
I'm leaning toward the Heatsink USA 5.88" at 28" length, mounted at the top of the cabinet, with a 92mm fan mounted to the cabinet ceiling centered above the heat sink blowing out of the cabinet. By pressing the sink fins up to the fan, it should pull cabinet air across the fins and out of the cabinet, so the fan will act as an exhaust as well as for cooling of the sink.
I did have an idea today based on a couple comments about using aluminum tubes in this thread. I know Steves LED sells aluminum tubing as a heat sink, but it looks too small for Vero 29s. Would something like this work?
http://www.zoro.com/value-brand-square-tube-al-2-34-in-inside-sq-3-ft-6aln9/i/G1834892/
It comes in 3' sections, and would fit perfectly across the top of my 36" cabinet. I could mount the cobs along the bottom of it, and then mount one of Steves pressurizing fan at the center point, blowing cabinet air into the aluminum tube and venting it out the ends of the tube through holes cut in each side of the cabinet where it meets the tube.
I think the tubing would have enough surface area to dissipate some heat in the event of a fan failure, enough to keep the Veros from burning up. One negative is that the tube walls are kinda thin at 1/8" so they may not transfer the heat as well. It would cost about 1/2 the price as HeatsinkUSA ($37 vs $74 including shipping), which is why I'm considering it. I'd love to have feedback from the guru's in this thread.
Thanks in advance, and keep up the fantastic LED science project that's happening here!
I stopped growing a few years ago, but now I'm looking to get back into it with a somewhat stealthy 2 small plant grow in a 36"w x 42"h x 18"d metal cabinet in my garage. After reading the LED threads here, I'm sold on LED and want to build a combo veg and flower light.
I'm planning to do 3 Vero 29 3k at 500 - 1.050 ma for flower, and 2 Vero 18 5000k at 500 ma for veg on a single heatsink. The veg LEDs would max at 28 watts, flower LEDs would range between 53 to 114 depending on how hard I drive them. They should run pretty efficient too, at the lower ma. I'd run veg and flower LEDs separate, so the max watts at one time would be 114.
I'm leaning toward the Heatsink USA 5.88" at 28" length, mounted at the top of the cabinet, with a 92mm fan mounted to the cabinet ceiling centered above the heat sink blowing out of the cabinet. By pressing the sink fins up to the fan, it should pull cabinet air across the fins and out of the cabinet, so the fan will act as an exhaust as well as for cooling of the sink.
I did have an idea today based on a couple comments about using aluminum tubes in this thread. I know Steves LED sells aluminum tubing as a heat sink, but it looks too small for Vero 29s. Would something like this work?
http://www.zoro.com/value-brand-square-tube-al-2-34-in-inside-sq-3-ft-6aln9/i/G1834892/
It comes in 3' sections, and would fit perfectly across the top of my 36" cabinet. I could mount the cobs along the bottom of it, and then mount one of Steves pressurizing fan at the center point, blowing cabinet air into the aluminum tube and venting it out the ends of the tube through holes cut in each side of the cabinet where it meets the tube.
I think the tubing would have enough surface area to dissipate some heat in the event of a fan failure, enough to keep the Veros from burning up. One negative is that the tube walls are kinda thin at 1/8" so they may not transfer the heat as well. It would cost about 1/2 the price as HeatsinkUSA ($37 vs $74 including shipping), which is why I'm considering it. I'd love to have feedback from the guru's in this thread.
Thanks in advance, and keep up the fantastic LED science project that's happening here!
BecauseIgotHigh
Well-Known Member
http://www.aliexpress.com/store/product/1200mm-L-198mm-W-18mm-H-LED-heatsink-aluminum-200w-Radiator-aluminum-heat-sink/612700_1624257648.html
Surface area -16195.25cm2? Fin height too short??
Heatsinkusa shipping fee too expensive, and the best option I have is a $50 heatsink MF35 Series heatsink from the local shop - Which is 13.7795 profile x 5.94" long x 1.88" fin height. I calculated the surface area for the local heatsink to be at 5989.58CM2. Good for 50w passive cooled? I have just been shopping around, already got 4xcxa3590 5000k cob, just missing the driver & heatsink. I'm aiming for 700ma drivers on all four cobs. Any help on the drivers & heatsink would be great help to me. Not sure whether to just get the heatsink from usaheatsinks, aliexpress or from the local heatsink shop, however 13.7795" x 5.94" is the biggest size heatsink.
Aliexpress looks promising, but not sure about the height of the fins from the link provided above is suitable for the COBs.
Surface area -16195.25cm2? Fin height too short??
Heatsinkusa shipping fee too expensive, and the best option I have is a $50 heatsink MF35 Series heatsink from the local shop - Which is 13.7795 profile x 5.94" long x 1.88" fin height. I calculated the surface area for the local heatsink to be at 5989.58CM2. Good for 50w passive cooled? I have just been shopping around, already got 4xcxa3590 5000k cob, just missing the driver & heatsink. I'm aiming for 700ma drivers on all four cobs. Any help on the drivers & heatsink would be great help to me. Not sure whether to just get the heatsink from usaheatsinks, aliexpress or from the local heatsink shop, however 13.7795" x 5.94" is the biggest size heatsink.
Aliexpress looks promising, but not sure about the height of the fins from the link provided above is suitable for the COBs.
salmonetin
Well-Known Member
...upsss just for my curiosity....NOTE: i noted all graphics from supra post are for vero v1...
...for vero v2... little differences.... example... vero 18 v2
...maybe needed post new graphs... and perhaps the plotted values for Vf and If for all veros... dreamming again...
pd... thanks Wilson... ...time to probe the engauge 4.1 way...
...Wilson...time to infusion...
Salud...os
...for vero v2... little differences.... example... vero 18 v2
...maybe needed post new graphs... and perhaps the plotted values for Vf and If for all veros... dreamming again...
pd... thanks Wilson... ...time to probe the engauge 4.1 way...
...Wilson...time to infusion...
Salud...os
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AquariusPanta
Well-Known Member
I got mad love for the Vero 18...
robincnn
Well-Known Member
I mounted a COB on a heatisnk and I am trying to understand how to measure thermal resistance °C/W of a heatsink.
Will it be change in heatsink temp/ watts of power (THS - TA)/P ?
If so, then where to measure the temperature of heatsink THS. Directly next to where COB is mounted or edge of heatsink? or take averages or complex integrals ?
Will it be change in heatsink temp/ watts of power (THS - TA)/P ?
If so, then where to measure the temperature of heatsink THS. Directly next to where COB is mounted or edge of heatsink? or take averages or complex integrals ?
SupraSPL
Well-Known Member
I think the C/W standard we are used to seeing is based on a very large temp difference between the heatsink and ambient (70C), which increases the efficiency of the thermal transfer. They are also based on vertical orientation and passive cooling in a still room. But in our case the heatsinks are often only a few degrees above ambient and horizontally oriented, so the C/W is really just a guide.
Going back to 2008, KNNA recommended a minimum heatsink surface area/dissipation W. Since then, quality LEDs have improved efficiency a lot (risen from about 20% to 40% efficient) so we use a smaller number now. Approx 25cm²/W for active cooling and 75cm² for passive cooling. There is more to the story though, the shape of the heatsink, thickness of the base, COB efficiency and air circulation in the space affects the outcome. The 75cm²/W figure is assuming about 40% COB efficiency, thick base, wide short fins and slight air movement (ideal conditions).
Many LEDs are running in the 30-40% efficiency range but they can go as high as 70%, so if we work with surface area/W of heat we would have a more accurate guideline. 40cm²/W of heat for active cooling and 125cm²/W of heat for passive cooling. I have been reluctant to go that route because I don't want to confuse the issue.
Anyway using those guidelines you should get a heatsink temp that is just a few degrees above ambient and a temp droop from .5-4%. I try to measure the hottest part of the heatsink without letting the photon and infrared output of the COB interfere (often in between the fins, behind the COB). @Greengenes707 pointed out that infrared thermometers can have a hard time with shiny objects. They can reflect infrared from other sources such as the COB or your own skin. Some IR thermometers seem to handle it better than others. I use a $15 baby food thermometer from Walmart and it does well with mildly shiny surfaces. If you are doing a lot of IR testing you can rough up the surface you are going to measure.
Going back to 2008, KNNA recommended a minimum heatsink surface area/dissipation W. Since then, quality LEDs have improved efficiency a lot (risen from about 20% to 40% efficient) so we use a smaller number now. Approx 25cm²/W for active cooling and 75cm² for passive cooling. There is more to the story though, the shape of the heatsink, thickness of the base, COB efficiency and air circulation in the space affects the outcome. The 75cm²/W figure is assuming about 40% COB efficiency, thick base, wide short fins and slight air movement (ideal conditions).
Many LEDs are running in the 30-40% efficiency range but they can go as high as 70%, so if we work with surface area/W of heat we would have a more accurate guideline. 40cm²/W of heat for active cooling and 125cm²/W of heat for passive cooling. I have been reluctant to go that route because I don't want to confuse the issue.
Anyway using those guidelines you should get a heatsink temp that is just a few degrees above ambient and a temp droop from .5-4%. I try to measure the hottest part of the heatsink without letting the photon and infrared output of the COB interfere (often in between the fins, behind the COB). @Greengenes707 pointed out that infrared thermometers can have a hard time with shiny objects. They can reflect infrared from other sources such as the COB or your own skin. Some IR thermometers seem to handle it better than others. I use a $15 baby food thermometer from Walmart and it does well with mildly shiny surfaces. If you are doing a lot of IR testing you can rough up the surface you are going to measure.
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