Are cobs worth it?

Growmau5

Well-Known Member
@Hybridway I don't really have enough time to take all the ideas from my brain and make them a reality. If that ever changes, sure Ill build some lights for sale.
building budget lights for profit does not interest me. I could see myself taking orders for custom CNC, laser, or waterjet designs with integrated controllers and shit. Something that would keep me engaged mentally and not be too repetitive like hand building 4 cobs bars. There are guys doing that cheaper, better, faster than I ever could.

I do have some ideas to cash in on the people that watch my videos tho. None are production ready, but they are all small diy items designed to help people, not necessarily to get rich off of.
-one idea that I have working right now is a tiny arduino that connects to your driver's dimming leads with simple wire bite connectors. the sketch/program just runs like this
82F or lower = 100% power to the driver 10-11v output
84F = 9v or 90%
85F =8v or 80%
etc etc the idea is to create what I call a Homeostatic dimmer. room gets hot, leds dim, room /AC starts to cool down, led intensity increases. Much better solution than just a high temp cut off that people are paying $40 for.

$12 in parts, 30mins to assemble by hand, no adjustment functionality, and no manual dimming override yet.
 

Attachments

Hybridway

Well-Known Member
@Hybridway I don't really have enough time to take all the ideas from my brain and make them a reality. If that ever changes, sure Ill build some lights for sale.
building budget lights for profit does not interest me. I could see myself taking orders for custom CNC, laser, or waterjet designs with integrated controllers and shit. Something that would keep me engaged mentally and not be too repetitive like hand building 4 cobs bars. There are guys doing that cheaper, better, faster than I ever could.

I do have some ideas to cash in on the people that watch my videos tho. None are production ready, but they are all small diy items designed to help people, not necessarily to get rich off of.
-one idea that I have working right now is a tiny arduino that connects to your driver's dimming leads with simple wire bite connectors. the sketch/program just runs like this
82F or lower = 100% power to the driver 10-11v output
84F = 9v or 90%
85F =8v or 80%
etc etc the idea is to create what I call a Homeostatic dimmer. room gets hot, leds dim, room /AC starts to cool down, led intensity increases. Much better solution than just a high temp cut off that people are paying $40 for.

$12 in parts, 30mins to assemble by hand, no adjustment functionality, and no manual dimming override yet.
Great idea! Never seen that, only full shut-down, which is good but not as good as your way that's for sure. Homeostatic dimmer.
What's your thoughts on LED venting? If it makes sense as much as it sounds, I would like all mine to be. For those Running big rooms, every little bit expelled makes a differance. I'd like to see them all w/ that option.
Just a thought on the dimmer. Don't know if those are your set #'s? And I've no idea what COBs & diodes can handle for temps.? But, if those #'s were bumped up by 7• then you'd be at a 2• fluctuation between what some people grow at & maybe to much for components?
Don't know if I said that right.
Could you up the temp #'s by 7-10• & still be at ideal temps for the components w/o causing premature deterioration? Because some people would rather grow at 85-90• rather then lower the lighting if they can't fully control their temps by means of AC. If they use CO2 then it's not that bad for the plants.
 

Fauxton

Active Member
Just an FYI:

There is another thread discussing the new Cree horticultural design. https://www.rollitup.org/t/cree-1000w-de-hps-replacement-reference-design.912866/page-3

I have posed a question on page 3. (About why 625nm has better WPE than 655nm. That contradicts everything I have previously read. See XQ-E @ http://www.cree.com/LED-Components-and-Modules/Applications/Color/Horticulture) I'd love some input.

PS - Time saver: most of the comments on that thread are shit right now. Turn it around!
 
Last edited:

MrTwist1

Well-Known Member
@Hybridway I don't really have enough time to take all the ideas from my brain and make them a reality. If that ever changes, sure Ill build some lights for sale.
building budget lights for profit does not interest me. I could see myself taking orders for custom CNC, laser, or waterjet designs with integrated controllers and shit. Something that would keep me engaged mentally and not be too repetitive like hand building 4 cobs bars. There are guys doing that cheaper, better, faster than I ever could.

I do have some ideas to cash in on the people that watch my videos tho. None are production ready, but they are all small diy items designed to help people, not necessarily to get rich off of.
-one idea that I have working right now is a tiny arduino that connects to your driver's dimming leads with simple wire bite connectors. the sketch/program just runs like this
82F or lower = 100% power to the driver 10-11v output
84F = 9v or 90%
85F =8v or 80%
etc etc the idea is to create what I call a Homeostatic dimmer. room gets hot, leds dim, room /AC starts to cool down, led intensity increases. Much better solution than just a high temp cut off that people are paying $40 for.

$12 in parts, 30mins to assemble by hand, no adjustment functionality, and no manual dimming override yet.
This is a really cool idea - basically what I do manually everyday in my hot climate lol
 

wietefras

Well-Known Member
i just cant wrap my head around pg 16 of that study

ok i see that the cree design edges the gavita in PPF/W at 1.82 vs 1.72, less than 10% better

so how in the heck do they replace the PPFD of 1000W with only 500W of LED?

what am i missing here? i could see if they were comparing lumens to PPFD or something and heavily weighting the better spectrum but going from PPF to PPFD should be a straightforward application without spectral bias (unless the gavita is throwing 50% of its light outside of the 4x4 and they dont count it? which aint a fair fight in an overlapping warehouse scenario)
As usual when people want to inflate led efficiency, they use these useless PPFD comparisons. Hang a Gavita Pro 1m high in a room with no reflective walls and see how little light falls on the 4ftx4ft square right under the lamp. Low and behold that's not even half of the light you see in a growtent from these fixtures. Completely useless test and pretty much an utter lie to even suggest it carries any meaning.

Indeed, you need to look at their actual PPF figures. Gavita Pro gives 1.6umol/s on the plants (after reflector losses and wall losses). Those Cree leds apparently produce 1.93umol/s after lens losses and assuming only 5% wall losses you'd be left with something like 1.83umol/s/W in a real world application. So at best you can expect 12.5% power savings with those horticulture leds at the power levels used in this test. Everything else is just because of a poorly designed test.

We run our CXB cobds to achieve 2.3 to 2.5umol/s/W. So that's much more efficient and we indeed end up with large power savings.
 
Last edited:

Growmau5

Well-Known Member
As usual when people want to inflate led efficiency, they use these useless PPFD comparisons. Hang a Gavita Pro 1m high in a room with no reflective walls and see how little light falls on the 4ftx4ft square right under the lamp. Low and behold that's not even half of the light you see in a growtent from these fixtures. Completely useless test and pretty much an utter lie to even suggest it carries any meaning.

Indeed, you need to look at their actual PPF figures. Gavita Pro gives 1.6umol/s on the plants (after reflector losses and wall losses). Those Cree leds apparently produce 1.93umol/s after lens losses and assuming only 5% wall losses you'd be left with something like 1.83umol/s/W in a real world application. So at best you can expect 12.5% power savings with those horticulture leds at the power levels used in this test. Everything else is just because of a poorly designed test.

We run our CXB cobds to achieve 2.3 to 2.5umol/s/W. So that's much more efficient and we indeed end up with large power savings.
I have Gavita hortistar at 1150.9w (457.8 radiant watts)
1.514 µmol/J , 39.8% efficient with a new reflector, new bulb.
univ of Utah sphere. edit: utah state univ.
 
Last edited:

wietefras

Well-Known Member
I have Gavita hortistar at 1150.9w (457.8 radiant watts)
1.514 µmol/J , 39.8% efficient with a new reflector, new bulb.
univ of Utah sphere. edit: utah state univ.
As seen in that white paper, Cree measured it at 1.72umol/J in their sphere. There were two more of those tests done by other universities and one came out at 1.75umol/J and the other (flat plane integration) at 1.8mol/s at 1000W. Growershouse also shows a test coming out at 1.7umol/J.

Gavita tested a 1000W in a 2m2 tent and came out at 1.6umol/Js average including wall losses. Which makes sense since they also claim something like 10% wall losses.

That's massive evidence supporting the 1.7+umol/J figure and as the scientific approach dictates, the outliers will be scrapped.

Then I have my own grow results using a 1000W Gavita Pro. If I use the 1.6umol/J figure for the Gavita and estimate wall losses at 5% for my Cree COB fixture, I come out at pretty much the same g/umol ratio for both these lights.
 

ttystikk

Well-Known Member
As seen in that white paper, Cree measured it at 1.72umol/J in their sphere. There were two more of those tests done by other universities and one came out at 1.75umol/J and the other (flat plane integration) at 1.8mol/s at 1000W. Growershouse also shows a test coming out at 1.7umol/J.

Gavita tested a 1000W in a 2m2 tent and came out at 1.6umol/Js average including wall losses. Which makes sense since they also claim something like 10% wall losses.

That's massive evidence supporting the 1.7+umol/J figure and as the scientific approach dictates, the outliers will be scrapped.

Then I have my own grow results using a 1000W Gavita Pro. If I use the 1.6umol/J figure for the Gavita and estimate wall losses at 5% for my Cree COB fixture, I come out at pretty much the same g/umol ratio for both these lights.
Wall losses get bigger when there's an aisle instead. Those are just giant light holes nothing is ever reflected back from.
 

ttystikk

Well-Known Member
Indeed.

You don't have aisles inside an Ulbricht sphere though :)

Neither do I in my grow tent or Gavita in theirs. So I'm lucky that I can simply use those figures and don't waste light on floors.
Lucky you, but not lucky- or even accurate- for those with open floor plans and aisles.
 

wietefras

Well-Known Member
Lucky you, but not lucky- or even accurate- for those with open floor plans and aisles.
Well then they should use tables on wheels and close those aisles when not needed.

This is not relevant for PPF figures anyway. The measurements you get from an Ulbricht integration sphere show how much light the fixture emits.
 

ttystikk

Well-Known Member
Well then they should use tables on wheels and close those aisles when not needed.

This is not relevant for PPF figures anyway. The measurements you get from an Ulbricht integration sphere show how much light the fixture emits.
While this is true it's not a complete picture. Just like actually getting traction on the road, all the lighting horsepower in the world does no good if it isn't hitting the intended target.
 

Sativied

Well-Known Member
The aisle argument only underlines how flawed the comparisson in the cree ref guide is. With tables and aisles one should still not use a 1000watter at 1m distance on a 4x4' table and waste over a third of the light on open space around it. A 660/750 at a lower distance would be enough to get a similar amount of light on the 4x4'.

I have Gavita hortistar at 1150.9w (457.8 radiant watts)
1.514 µmol/J , 39.8% efficient with a new reflector, new bulb.
univ of Utah sphere. edit: utah state univ.
fyi the hortistar is specifically the reflector part. Unless you actually wanted to imply you hooked it up to something else than a gavita pro fixture.
 

Gator44

Active Member
In my opinion absolutely, just the heat factor alone is incredible I have panels of cxb 3070's, vero 29's and 2 panels of vero 10's I couldn't be more impressed with the lights. Plus all 4 lights run on the same circuit its un real how low the power consumption is plus passive cooling means I simply put a fan on and you can touch the back of where the led is mounted for as long as you like. I couldn't speak highly enough of cob leds I really really love my vero 10 panels and so does every single plant that has been under it.
 

ttystikk

Well-Known Member
In my opinion absolutely, just the heat factor alone is incredible I have panels of cxb 3070's, vero 29's and 2 panels of vero 10's I couldn't be more impressed with the lights. Plus all 4 lights run on the same circuit its un real how low the power consumption is plus passive cooling means I simply put a fan on and you can touch the back of where the led is mounted for as long as you like. I couldn't speak highly enough of cob leds I really really love my vero 10 panels and so does every single plant that has been under it.
And as if that wasn't enough, it makes better buds with more frost.

That pounding you hear is the sound of nails being driven into the coffin of light bulbs.
 
Top