Heatsinks for DIY LED lamps

iceman3000

iceman3000

Well-Known Member
OK as i want to build the fixture and be able to add and remove cobs as needed is why i keep asking about single sink so not stuck with one long bar with cobs on it, would like to strap them in a frame... so the only choice i have is the 5.88 at 7 inches long per sink and cob combo or is their a better choice

thanks iceman..
 
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iceman3000

iceman3000

Well-Known Member
Ok lets go back to fan cooled cob.. 1 cob 1 sink 1 fan would this work for cxb3590 on hlg 120 1400 @50w
Thermaltake CL-P0503 80mm Rifle Bearing CPU Cooler for AMD 65W Series
upload_2016-1-9_15-40-25.jpeg or something like this as it couldn't be more then 2or3w draw
 
iceman3000

iceman3000

Well-Known Member
dam went to place order with heatsink usa (8ct. 5.88 x 38 580ish and another 80 for shipping killing me, has to be a lighter and cheaper option
 
iceman3000

iceman3000

Well-Known Member
HI guys & gals
this will be my last post on this topic need to know what everyone thinks
working with a 4x10 space for lights. 3 side enclosure
24 cxb 3590 hlg driver 120 1400 (3) cobs or 185 (4) cobs 90 reflectors

(1) run 3 cob space 16 inches depth and 8 bars space 15 inches width that's 4x10

(2) run 3 cob space 16 inches depth and 8 bars space 12 inches width that's 4x8

(3) run 4 cob space 12 inches depth and 6 bars space 16 inches width that's 4x8

this is the last decision i have to make befor i order the sinks

thanks for any input on the matter
iceman3000
 
Maine_Coast

Maine_Coast

Well-Known Member
iceman3000 said:
HI guys & gals
this will be my last post on this topic need to know what everyone thinks
working with a 4x10 space for lights. 3 side enclosure
24 cxb 3590 hlg driver 120 1400 (3) cobs or 185 (4) cobs 90 reflectors

(1) run 3 cob space 16 inches depth and 8 bars space 15 inches width that's 4x10

(2) run 3 cob space 16 inches depth and 8 bars space 12 inches width that's 4x8

(3) run 4 cob space 12 inches depth and 6 bars space 16 inches width that's 4x8

this is the last decision i have to make befor i order the sinks

thanks for any input on the matter
iceman3000
Click to expand...
I would go with 6 heatsinks (40") and 4 cobs per hs using the HLG-185. This will cover the 4x10 space at 30 W/sqf. Also, no need to post the same thing in multiple threads.
 
nogod_

nogod_

Well-Known Member
@SupraSPL

What's your take on how much shape influences surface area requirements?

On the Cutter site, they claim that mechatronix lsb-9950 can handle 30w of heat but with a surface area of only 1392cm^2, that hardly seems like enough surface area to effectively cool 30w passively (As greengenes pointed out).

But my understanding is that your passive figure (120cm^2/w ?) is derived from the heatsinkUSA heatsinks not something shaped like the mechatronix.

Being able to passively cool a 35w or even a 50w cob for $12 would be a gamechanger!
 
Led Newbie Oz

Led Newbie Oz

Member
Has anyone calculated the thermal resistance Rth required to passively cool a cxb3590 @ 56% 61%
I think it will give us a more accurate way of calculated heat-sink requirements.
 
SupraSPL

SupraSPL

Well-Known Member
nogod_ said:
@SupraSPL

What's your take on how much shape influences surface area requirements?

On the Cutter site, they claim that mechatronix lsb-9950 can handle 30w of heat but with a surface area of only 1392cm^2, that hardly seems like enough surface area to effectively cool 30w passively (As greengenes pointed out).

But my understanding is that your passive figure (120cm^2/w ?) is derived from the heatsinkUSA heatsinks not something shaped like the mechatronix.

Being able to passively cool a 35w or even a 50w cob for $12 would be a gamechanger!
Click to expand...
Yes the 120cm²/ heat W figure is based on the passive friendly profiles with fins, horizontally oriented, a low thermal rise and assuming some air movement in the space. If the heatsinks were shaped more efficiently (radial style is a good example) then you could reduce that number. You could reduce the number further if you were willing to accept a higher junction temp, which is what many manufacturers do for their recommendations, probably because they would not expect the LEDs to be run or 12 hours/day.

I have not tested any radial heatsinks but some do look promising, including the LSB9980-B for $12.61. I would not expect it to do well with a COB at 50W dissipation, but possibly 37W or 25W dissipation.
 
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