COB Talk

GrumpyToker

GrumpyToker

Well-Known Member
Greengenes707 said:
I hear a lot of thought. Lets see some testing or proof anyone?
I used to be pretty anti passive. But things have changed and passive doesn't mean 85c and heavy as hell. As well as active does not mean 25-30c.

Everyone thinks their active units run a few degrees over ambient??? Do please show? I don't want to see any sink temps. I want case temps? Specially for an active setup. If you're a DIY'er of more than one light and don't have a thermocouple...come on. And if we are talking about an inclosed case unit(retrofitted lights, using project boxes, fin shrouds,...), active units lose most of their advantages over passive. Of course that is all in a controlled and stagnant testing environment that I have tested in. Once passives are put into a grow room...the slightest air movement is as good as an active fan. "Active raw/open frame" will gain some from a grow room air movement too, but "active enclosed" not so much.
I used to hate BML for recommending to use a circulation fan...and still do. You should not have to recommend that, the lights should be perfect with bad air movement and amazing with great air movement. But the fact of the effect, is true. In a grow room, fan drop Tc of a passive units significantly.

I know many people who have built either simple to pretty complicated "in case of fan failure" systems for their lights. They aren't needed passively. Fans and all components related...not needed.
140mm Pin sink will be under 20$ in a few week from PLC. A better cost value than HSUSA and you can space as needed and save a good amount of weight. For high efficiency build(50%+, basically every cob build from here out), no one is going to need more than a 140mm. And higher wattage only gets better for the pins vs extruded bars. And smaller profiles will be cost less.
All that said...the cost can be cheaper than an active unit to achieve the same Tc.
View attachment 3663344

Then of course the very basics of heat in the room...active or passive...they both contribute the same amount of heat to the environment...technically the active actually contributing more.
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Take my money for those 140mm pin heatsinks.
Send me a PayPal order for 8 so I can preorder them from you.
 
JorgeGonzales

JorgeGonzales

Well-Known Member
ttystikk said:
Temperature droop curves are not subjective. They're as empirical as it gets.
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The difference just might not be as dramatic as you expect. My cob makes 172lm/w at Tj=35C, and 164lm/w at 70C. About a 4% drop, or 12 watts extra to keep my 300W build making the same lumens. Except fans don't run on love, so add eight fans and well...

So temp droop exists but isn't so significant that other considerations don't matter. And a 45C rise is mediocre passive cooling at best.

Actually I'm glad this thread made me do the math. The power usage might not be dead even, but it is closer than I thought.
 
robincnn

robincnn

Well-Known Member
ttystikk said:
Temperature droop curves are not subjective. They're as empirical as it gets.
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I agree with you. The lower the case temp the better. 25C case temp better, even lower is even better.
What i am trying to say is between active and passive cooling the loss of Photons is 2%-3% and Good Passive design can be better depending on what is your preference.
Some may want the extra 2%-3% cob efficiency and lose 1%-2% by running active cooling fans. Some prefer simplicity and reliability of passive.

For small lamps consider $25 per heatsink for passive cooling, keep temps around mid 40's C. It will be a considerable expense to get the temps down to 25C or lower
If you have dozens of cobs then perhaps a cooling method to bring temps down to 25C would be affordable. Until then passive or active
 
J Bleezy

J Bleezy

Well-Known Member
I'm almost done with my first cob run, about 2 weeks til it comes down.
The coverage of the light is amazingly even, most buds will probably end up being the same size and all look like they will be sellable.
I'm seeing zero foxtailing which is not normal with the strain I'm running. The buds definitely look much smaller than normal, but a lot of that probably has to do with no foxtail.
I'll have to see final results before I decide wether or not to build 3 more of them, but I'm really liking it. Looks like they'll be some quality nugs.20160421_182515.jpg 20160421_182618.jpg
 
J Bleezy

J Bleezy

Well-Known Member
Nah. That pic is from last week, just what I had in my phone. I've been running it for about 2 years now and it's a weird one. The pistols don't die off until real late (compared to the time it takes to flower). I haven't even got around to checking trichs yet, but honestly it looks ahead of schedule.
 
ttystikk

ttystikk

Well-Known Member
J Bleezy said:
Nah. That pic is from last week, just what I had in my phone. I've been running it for about 2 years now and it's a weird one. The pistols don't die off until real late (compared to the time it takes to flower). I haven't even got around to checking trichs yet, but honestly it looks ahead of schedule.
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Experience with the pheno trumps looks every time. It looks good, and early, lol but what do we know? All we see is a pic ,lol
 
J Bleezy

J Bleezy

Well-Known Member
I'm not even sure of the strain lol. I was helping a friend clean up his room. He and his brother had got into it big time and he decided to scrap all of his brothers strains in fear that cops might come and he'd be over his plant cound. I took a strawberry cough (which ended up being terrible) and this one. It was labeled "chemX13" and I could never find definite info on it. It definitely has a RKS smell to it.
A few months ago I did see some G13XChemdawg seeds, but who knows.
 
ttystikk

ttystikk

Well-Known Member
J Bleezy said:
I'm not even sure of the strain lol. I was helping a friend clean up his room. He and his brother had got into it big time and he decided to scrap all of his brothers strains in fear that cops might come and he'd be over his plant cound. I took a strawberry cough (which ended up being terrible) and this one. It was labeled "chemX13" and I could never find definite info on it. It definitely has a RKS smell to it.
A few months ago I did see some G13XChemdawg seeds, but who knows.
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Fire needs no names, it speaks for itself.
 
J Bleezy

J Bleezy

Well-Known Member
I should've noted that the pic was from last week in the post. I can give an update in a couple weeks, but enough about me and my plants. :-)
I just posted the pic in reference of the no foxtailing, but there probably wouldn't have been much foxtailing then anyway. Admittedly, I was high.
Anyway, I kept my light (12 cxb3590@1050ma) about 16" from the canopy and not a problem anywhere. I'm thinking I'm gonna try 12" next time and see what happens.
 
ttystikk

ttystikk

Well-Known Member
J Bleezy said:
I should've noted that the pic was from last week in the post. I can give an update in a couple weeks, but enough about me and my plants. :-)
I just posted the pic in reference of the no foxtailing, but there probably wouldn't have been much foxtailing then anyway. Admittedly, I was high.
Anyway, I kept my light (12 cxb3590@1050ma) about 16" from the canopy and not a problem anywhere. I'm thinking I'm gonna try 12" next time and see what happens.
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I'm seeing a dramatic disappearance of foxtails, too.
 
kmog33

kmog33

Well-Known Member
Open or lenses. By I'm in tents so lenses/reflectors are less of a factor unless I'm planning on overcrowding my canopy.


Sent from my iPhone using Tapatalk
 
Evil-Mobo

Evil-Mobo

Well-Known Member
kmog33 said:
Open or lenses. By I'm in tents so lenses/reflectors are less of a factor unless I'm planning on overcrowding my canopy.


Sent from my iPhone using Tapatalk
Click to expand...
On my T2-2100 I am running reflectors with no lenses and very happy thus far I am in a tent as well.
 
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