LED CRI suggestions for veg flower, or does it matter?

[wietefras]

i just get a little lost when it comes to the heatsink requirements. 110cm/watt seems like a whole lot of heatsink

I don't think anyone actually uses that much. 110cm2 would be 17 square inch.

COBs will need a proper heat sink, but if it's a CPU or led heat sink the description should tell you which wattage range it's good for. No need for calculations really.

Led strips normally don't need a heat sink, but I like to add an aluminium backing at the very least for some extra rigidity. Make it a U channel and you get extra cooling from the vertical sides. Those aluminium channels are very cheap.

 

[Unagi]

110cm2 is 43.3 square inches btw

 

[wietefras]

110cm2 is 43.3 square inches btw

You need to divide by 2.54 twice since it's squared. So 110cm2 really is 17 square inch like I said above.

 

[Unagi]

You need to divide by 2.54 twice since it's squared. So 110cm2 really is 17 square inch like I said above.

You're right, not sure what I was thinking.

 

[Randomblame]

ok, does anyone know what the C/W/3 rating mean? if i'm looking for a heatsink to cool a 100w cob, i know the cw3 rating means something, but maybe i'm just too burnt out to get it currently haha. it seems the lower the cw3 number- the better it performs. i just wish it made a little more sense to me. i know i have a cob that is 1 in x 1 in, and i need heatsink recommendations for 50w actively cooled, and 50w passively cooled 11ow active/passive, but instead of a direct recommendation, i'd rather have the knowledge to make the choices myself, i just don't have the info needed. i'll do some more reading, and post back here tomorrow. Thank you! hopefully i figure it out buy then. if i do gain the knowledge, i will write up a guide for these forums, i have no problem giving back to the community. what comes around, goes around.

If you really want to understand this stuff this is a good point to start from

https://en.m.wikipedia.org/wiki/Thermal_conductivity

 

[nonamedman420]

yeah i only stated 110 because it was a number i seen thrown out a few times on a different website. i was thinking about the cpu heatsinks myself, but i think this guy wants passive if possible due to the room being climate controlled, but i said fans would be a good bonus, just in case the ac/chiller shit the bed and he wasn't there to pull the plug before it melted. i have to bounce some ideas off of him and see what he thinks. i do know i'd like to see if there would be a way to make it shut off at a certain temp, i'm sure there has to be a way, and it should be mandatory for diy lights due to there being a potential fire hazard. for all i know, he may want to go the strip route like was suggested above, that sounds pretty simple, thank you wietefras!

 

[Randomblame]

You could make your own heatsinks. Use a 2-3mm thick aluminum base plate and add some U-channels to the backside to increase the cooling surface. The one below is 24x 14" with eight added 20x 20x 20mm U-channels. Thermal tape works great or simply use 1$ thermal glue from e3ay.

 

[dbrn32]

ElG-240 is a better option for a budget. look at the efficiency its 93% vs 93.5%

0.5% efficiency loss for a 25% cost saving

1.622a vs 1.490a is the only disadvantage if you wanted to overdrive them but 1212s arent great anyway so i wouldnt.

Don’t the elg’s derate at 120v, making that only true at 230v input?

 

[diyled]

Don’t the elg’s derate at 120v, making that only true at 230v input?

Yes them numbers are only true @230v but in this case at 115v the hlg-240 would be 91%and elg-240 would be 92% @ full load according to the datasheet.

 

[dbrn32]

Yes them numbers are only true @230v but in this case at 115v the hlg-240 would be 91%and elg-240 would be 92% @ full load according to the datasheet.

Isn’t that exactly the opposite of what you just agreed to though? The elg won’t make full load at 120 volt nominal input? It may or may not be 92% of input power on the output side, I’m not really sure. But it’s not a 240 watt driver at low voltage input, is what I was trying to say.

 

[diyled]

Isn’t that exactly the opposite of what you just agreed to though? The elg won’t make full load at 120 volt nominal input? It may or may not be 92% of input power on the output side, I’m not really sure. But it’s not a 240 watt driver at low voltage input, is what I was trying to say.

I thought you were on about efficiency. Yeah you are right My bad.

 

[dbrn32]

I thought you were on about efficiency. Yeah you are right My bad.

No big deal. As long as people understand what they’re getting I don’t disagree there. It’s just a little more complicated than saving a few bucks with elg series in my opinion. They’re excellent buy for someone with higher voltage source.

 

[OLD MOTHER SATIVA]

or get a tiny heatsink or NO heatsink and small muffin fan and cool them better[efficiency] than expensive passive heat sinks
come on dude..you must have read this too

 

[skoomd]

or get a tiny heatsink or NO heatsink and small muffin fan and cool them better[efficiency] than expensive passive heat sinks
come on dude..you must have read this too

That's my biggest issue with COBs. If you want to run them with their own passive sinks, they're like $30-45 a pop. It's usually better if you can get a large aluminum sheet, but then that'll reduce airflow around your light that your exhaust is sucking out. And if you use CPU coolers, you have to do a bunch of extra wiring and crap, plus it will be looooud. And if a fan goes out and you dont notice quickly, you'll burn that cob out in no time.

With strips, it's way cheaper. You can use even just simple U frame as a sink, which is like $5-8 per strip tops. But if you want to use real heatsink, it's only like $8-15 per strip and it's all passive.

Hell, the bridgelux EB gen 1 and gen 2 strips dont need ANY heatsink at 700mah.

 

[skoomd]

The main reason for 90 cri over 80 with white LEDs, is that 90 cri shifts the spectral peak over more into the red/far red spectra, which is obviously beneficial for yields and overall photosynthetic rate. But more red and especially far red will promote elongation of the internodes, which may not be desirable in veg. 2700k and 90 cri would not be much good for veg.

I have long wondered how CRI affects phenotypic expression too. When CMH hit the market with 90+ cri and I started seeing the huge increases in quality, unique bud structures, and way more color coming from plants grown under them I started thinking that CRI may play a role in that. But I think 80 cri white LEDs bring out the phenotypic traits plenty well enough anyways, but just food for thought.

 

[Randomblame]

I prefer selfmade heatsinks. A 3-5mm thick alu sheet in 1100 x 200mm and five u-channels 25x 25x 25x 2mm, l.:1100mm, glued to the backside would be a heatsink with ~9900cm² surface area and 5-7mm bottom plate.
Thermal tape is great for that and for me it works perfectly and the heatsink heats up evenly.
That's enough for 90w of pure heat or 200-210w COB(4x 50w or 6x 34w). And two of them in parallel would allow enough airflow. Call the next scrapyard and ask for aluminum plates, used u-channel or heatsinks, you can get it at the kilo price(3$).
Heatsink on pics below(600x 350mm) is made this way, currently 145w, max. temps are ~45°C near the €€3

 

[OLD MOTHER SATIVA]

re fans..everyone needs air circulation..sink fans are great for this too
unless its under your bed..its not noisy..some fans are really quiet

its not much extra work..its lots cheaper..do you wanna make barriers or grow ..fans willnot let you down and even if you have a cheap computer sink..@50 w per you will not burn them out..cheapchina sink.fan three years..quite and still running

re over thinking cri kelvin.added red etc...

nah..if you have good leds/cobs it doesn't matter hardly at all what cri/or kelvin

i just did 5000 against 3000..veg flower..the 5000 a bit better..

but then again i only know it from actually trying it..

unless it is all just theoretical

don't over think this thing..

 

[skoomd]

re fans..everyone needs air circulation..sink fans are great for this too
unless its under your bed..its not noisy..some fans are really quiet

its not much extra work..its lots cheaper..do you wanna make barriers or grow ..fans willnot let you down and even if you have a cheap computer sink..@50 w per you will not burn them out..cheapchina sink.fan three years..quite and still running

re over thinking cri kelvin.added red etc...

nah..if you have good leds/cobs it doesn't matter hardly at all what cri/or kelvin

i just did 5000 against 3000..veg flower..the 5000 a bit better..

but then again i only know it from actually trying it..

unless it is all just theoretical

don't over think this thing..

Interesting about the 3000k vs 5000k. Do you have any pictures? Are the yields the same? I'd assume quality under 5000k might be better.

And my grows are in my bedroom actually, so the noise is a huge problem for me. my normal computer fan for my PC can be bothersome, let alone like 12 of them on full blast lol.

What about emerson effect?

In my experience with blurple LEDs, I got way bigger yields using more red dominant spectrum panels than ones with more blue.

 

[wietefras]

That's my biggest issue with COBs. If you want to run them with their own passive sinks, they're like $30-45 a pop. It's usually better if you can get a large aluminum sheet, but then that'll reduce airflow around your light that your exhaust is sucking out.

CPU coolers are a 7 euro a piece. For larger numbers of COBs, I used aluminium bars to mount the COBs on. Basically created my own led strips. Which you could cool with U channel too.

And if you use CPU coolers, you have to do a bunch of extra wiring and crap, plus it will be looooud.

You can run fans at 5V. You really don't hear them at all. Or at 9V for some more air flow and still more quite than the exhaust fan.

And if a fan goes out and you dont notice quickly, you'll burn that cob out in no time.

That's simply not true.

 

[skoomd]

You can run fans at 5V. You really don't hear them at all. Or at 9V for some more air flow and still more quite than the exhaust fan.

Well what size in MM fans are we talking? 120mm can be pretty quiet at 5v, but 80mm fans are too loud for me even at 5v. Cheap fans are of course louder than more expensive ones too. And the more cobs you have running, the louder it gets.

That's simply not true.

It would depend what the COB is running at. But an active heatsink has faaaaar less surface area than a passive sink capable of the same cooling load. I have heard from quite a few people that they had a fan go out running a COB at 75-100w+ and the COB burned out before they noticed. Whether that be hours, days, or even weeks who knows. But it has definitely happened to people before. And they often swap to passive afterwards