Heatsinks for DIY LED lamps

Keesje said:

In general: Even the slightest airflow will cool your heatsinks down.
I did a test with a very precise thermometer attached to a heatsink. Even when I walked by, I saw the numbers go down. Not a lot of course, but still.
So with a fan it will work even better.
Another (and imo an even more important) benefit is, that with having a fan above your led pushing the air down, is that more heat will get to your canopy.
Where with HPS you want to suck away the heat, with led we sometimes want the heat to go to our leaves to reach the best temperature.

If you want to know if only a passive heatsink will do, you can use this calculator.
You said you have plenty of time, so perhaps you can figure it out.
I once found a much simpeler calculation somewhere, but can't find it anymore. I was something like: If you want to cool something 1 degree down, you need x cm2 of aluminium surface. It was over simplified of course, but it was a handy tool.

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SupraSPL had a really cool post here. Well worth a read for general guidelines on passive and actively cooled heatsinking requirements.

Nice!
He claims that 120 CM2 per Watt of led is ok for passive cooling.
It is just a rough guideline of course.
When you don't run your leds too high, they need less cooling anyway.
Also the ambient temperature is important.
But as a guideline it is something to hold on to.

Hey Fam

Trying to find a middle way on heatsinks for a project im doing...
I wanna figure out a way to make sure im not over dimensioning my heatsinks.
I want the heatsink to reach around 40-45°, using approx 40-50w per 2 foot of alu u-channel.
Using cutter strips and running the diodes about 0.4w / diode so similar to be running a 2foot double f-strip at 50w i guess.
The reasoning is this: our space is always cold in winter and the current leds we use dont heat anything, its Fotop boards that only heat up a couple of degrees ambient as they are run at 0.15w per diode.

So basically im wondering about anyone whos doing strips with hard run diodes and u or c-channel alu as sinking, what are your sink temps like? And what dimensions of your sinking?
Im gonna tag @ANC as i know he builds lights with f-strips on these power levels...

My ecosunlite that I won and was sent, used to heat up the tent in such a huge way, I couldn't believe it. Putting all your drivers, sinks, and diodes(COBs/monos in that case) in a tight little metal box with 6 fans trying to cool it all was a fantastic heat source.

Airwalker16 said:

My ecosunlite that I won and was sent, used to heat up the tent in such a huge way, I couldn't believe it. Putting all your drivers, sinks, and diodes(COBs/monos in that case) in a tight little metal box with 6 fans trying to cool it all was a fantastic heat source.

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Its an openspace and quite cold in the winter. Im hoping a bunch of sinks at 45-50C will do it come winter time.

Right at the beginning of this thread, Alesh mentions 110cm²/W. That was back in cob days. I have no idea how that translates to strips. Even 560mm double row like F564's. Although I would tentatively suggest required sink area could be lower. There must be some on here running the F doubles (~46v) that could give you readings from their strip/sink combos.

Tagging @ANC is probably good idea. Think he uses a box/rectangular section. Remember some nice examples he posted up a while ago. But cannot recall if he mentioned his strip temps. Expect he experimented and the section he uses will cover the extreme use case.

I think I get why you want to use minimal material, but don't understand how heatsink size is going to impact btu produced to open space during winter. The wattage of heat energy is almost same? X watt of Fotop or X watt of cutter Opti/cree/nich strip. Gap in efficiency is small. I stand to be corrected? Only way I see to make a gain is to get the air circulating back down to the plants, instead of rising directly above the lights where it would be no benefit to the plants in winter.

Rocket Soul said:

Its an openspace and quite cold in the winter. Im hoping a bunch of sinks at 45-50C will do it come winter time.

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If it's an open space, good luck man.... I dont think it's possible with just harder driven LEDs Heatsink. But I could be wrong.
If it's a 4x4' in say a 10x12' room, at that point I'd say just seal it off and use a stand up oil drip radiator. Exhausting would need to be done quickly and un frequently. Putting the run just inside a tent would help the entirety of that situation in a HUGE way. Total control of environment and hotter heatsinks would actually kick ass for putting constant heat out. The heat would accumulate and be better utilized in a tent so much more. Plus you could constantly exhaust still.
If you can't do a tent, just at least throw up some 1" thick reflective foam board sheets around the area to contain it. I think that's what you need to focus on moat I to really benefit from heat produced via lighting.
And you know already of course, have your drivers in the area too. Duh...
But if ALL else fails, throw a 1,000Watt HPS in an open bat wing reflector and Bob's your uncle.

About 5 inches wide is enough sinking for F series at roughly 100W to not get terribly hot. You can handle them.

Hi guys, I am planning on using these 4 CLU048-1212 COBs with HLG-185H-C1400B, and I will probably run them on 150-200W. Do you think those heat sinks will be sufficient with 7cm fans running at 12V ? What temps should I be aiming for and how do I measure that accurately? I've tried test running them without fans on for 2-3 mins, but they started getting kinda hot - I could still keep my hand on the heat sinks tho. It is just prototype for now hence the ugly wiring Any help is greatly appreciated

They should be fine depending on the supply are temperature. If need be, put some flexible duct on the fans and supply them with cooler air rather than circulating hot air at the top of the tent/room. I have one chip running with no fan at 50W and it is not something you would want to have your hand on for a long time. A fan really cools them down, again, depending on air temp.



These are not ideal for passive cooling, the fins are too closely spaced, these were designed for fan cooling. I measured these with an oven meat probe. Just measured the temp, 142 F in a room that is 28 F. There is a oscillating fan in the room but this light is in a dead spot.