Heatsinks for DIY LED lamps

Hey Supra, Thanks for the quick response! This eases my anxiety.

This was just in my kitchen. I let it run for an hour, then used a high end meat/candy thermometer (I'm a hobbyist chef) with a drop of water on the back of the heatsink behind the COB. The highest readings I saw was 140*.

I'm aiming for a 5-8 yr life span with these lights. I'm sure once it's in the grow room it will have at least an oscillating fan brushing over it now and then. I believe that'll take care of it. So 130F is acceptable? I would like to keep the lenses on to help with penetration but at this point I'm leaning towards removing them.

We're hoping to get 10-12 of these units in a 6 x 12 room. There will be enough heat removal as the room was designed for 4 x 1k HPS.

I like your temp method, good call. I expect you will find much lower temps in the tent due to circulation/ventilation, especially considering it is setup for HPS. If for any reason you are still getting 130 once it is in the tent, I would advise adding a fan, any old fan would make a huge difference but 140mm matches the 5.88" profile.

I don't think the lenses will contribute much to the heatsink temp, although they may increase the temp at the surface of the COB (LES) a bit. Once the heatsink temp is down to ~100F, that will relieve the LES temp quite a bit as well. When I was temp droop testing a pair of 80W Vero29s, there was no difference in temp droop with lenses on vs lenses off, therefore no difference in junction temp. Those lenses were not sealed though, so I will run another test with a sealed lens.

Thanks for the info and your expertise!

It's funny, if I would have found this website a year ago I would have strongly advised against sanding your heatsinks to apply thermal paste. I guess you learned it on your own though lol. I have a huge amount of computer expertise and knowledge, and those CPU heatsinks are designed and polished to be as smooth as possible. The most important thing is to reduce air bubbles! no air bubbles that hold heat.

Bonjour
@kliend which method do you use to applly TIM without air bubbles?
I done it the first time few months ago for my first built...I applied some on the cob and some on the hs with a rasor blade...a very thin lay(I wasn't sure it was enough but everything fine since...!)I am sure I wasted more TIM than I used!
But next time I will use thermopads...work well enough imo!
Have a great day ★

I have a friend with a professional metal shop I could get to lap my down.

The cpu heat sinks are probably done pretty well, but the stuff from heat sink USA I doubt is

Hey guys. Oh I don't put too much thought into it anymore.

After swapping CPUs hundreds of times, and they're all running about the same temps, I just stopped caring lol.

I just put a dot of goop on, slap down the chip, and screw it in. It is best to screw alternating back and forth to ensure all the paste doesn't go out the opposite side. I used this stuff: Arctic Silver AA-14G Alumina

That sounds fancy. I just used the basic arctic silver.

Ok, the lamps arrived today. And they look gorgeous! Larger than expected (see pics), but also much sturdier. 50W passive is no problem, it feels barely warm. I checked the chip, and it's genuine cree cxb3070 - no surprise here. Only drawback is the driver: looks and feels cheep. I hope it will do, but next time, I will buy the drivers separately and mount them myself. Though for a $40 lamp, I can't complain. Including shipping and taxes, it's about $55 per pc. I really have to work on the container idea. On a sidenote: the track system is simply awesome. 2 Clips to fasten each lamp. No cable mess. Easy to check on / clean and stuff. It allows a precise setup for each cob ray, and even comes with an aluminium case to hold/cool the driver, which means you can go for a cheaper pcb only driver.

@qwerkus i must have missed it, where did you get those from?

sureshot138 said:

@qwerkus i must have missed it, where did you get those from?

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Directly from a chinese factory. Negociated over alibaba (a real pain). 10pc was absolute min; they are looking for 100-1000moq.

Bonjour
@qwerkus do you know the bin of those cxb3070?
Have a nice day!

littlejacob said:

Bonjour
@qwerkus do you know the bin of those cxb3070?
Have a nice day!

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Good point. Asked at least 10times, but never got a clear answer. I guess most of them are AD, but I can only confirm once all lamps have been tested. Maybe some BBs are hidden in the lot If you want a precise bin, you have to get the chips yourself and have them shipped to the manufacturer. Too bad I missed the cree price change by a week or so. Now you can get cbx3070 good bin for 32$/pc (down from 36$). cxa3070 is at 21.5$/pc!

Where can we get CXB3070 top bins for $25? That would be very welcome price break

SupraSPL said:

Where can we get CXB3070 top bins for $25? That would be very welcome price break

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Just checked again: 25$ is for large quantities. Retail goes for 32$. Sorry to disappoint. Still makes me wonder have my chinese guys managed to pull a 40$ cxb3070 lamp including reflector, glass cover, huge aluminium heatsink and (albight cheap) driver ?

That is a good question, if they can do it for $40 without some kind of catch that is very impressive. Even $32 is surprisingly low for a CXB3070. Do they give you any part numbers at that price and is it advertised somewhere?

SupraSPL said:

That is a good question, if they can do it for $40 without some kind of catch that is very impressive. Even $32 is surprisingly low for a CXB3070. Do they give you any part numbers at that price and is it advertised somewhere?

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Actually 32$ is from jerry @Kingbrite. Don't you get his newletter ? For the rest, without driver, the price for a complete lamp was actually 35$/pc. I can pm you the PI if you are interested- can't make it public though.

I didnt know there was a Kingbrite newsletter. I do get email updates of their stock but I have never seen pricing included. I will msg him to add me thanks for the heads up. Yes I would be interested in the contact to check it out thank you.

salmonetin said:

...other crazy idea...for cob lamps... we can use small - medium solar panels (but powered for light of cobs) to power a fan/s... or small batery/ies...

...... .........



Saludos

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Overlooked this one. Good call, but tricky. Large fans like 120-140mm can easily draw 2W. If you count one fan per COB, and use like 8-10 COB arrays, this is a lot of power for a solar panel. Than comes the mounting problem: granted you find enough surface, where do you fix it ? Sides get covered by plants, and the top has the COBs. Maybe cheap flexible PV where you drill the cob openings through - but this is really messy, as you'd probably cut off entire rows this ways. And finally comes the cleaning problem. PV surface needs to stay clean for optimal power production, which is a real pain when working with large plants. Frankly: because of all those reasons, I gave up on finding a practical solution for this but I'm open to suggestions.

Bonjour
Is there cxb3070 binned under AB? (Z4?)
I try to find an explanation to this price!
Have a great day ★

Maybe they screwed me, and it's a fake cree, or a cxa. I'll try to get another pic of an unmounted lamp, than you can see for yourself. I don't have another cxb3070 at hand to compare, so what appeared genuine at first glance might not be so after all...

EDIT: Here you go. Anyone cares to compare with some cxb3070s from mouser or digikey ?