Running vero c units at 75%?

I hope to use 6 of these units that are 200W each (1200W grand total). As I learn more about cobs it's seems that running them above 75w? reduces efficiency. These cobs are being driven at 100w each and I don't have much clue on what that means for efficiency/light output etc.

If running them at 75% that would, unless I'm mistaken bring them to the upper limit of what you guys think is an acceptable W to use?.

In a 3x10 lay out what differences in ppf would this have. Are you able to compare running the lights at 100% / 75%. I already know the rough ppf at 100% but if I'm not mistaken it isn't a case of deducting 25% due to cobs becoming more efficient when cooler?. Is that only in terms of electric use.

Last question, does running the vero C units at 75% justify using them over another product that is running more diodes already within the 75w limit?. Even if that means using older tech. Sorry another question ;p. If they are good to use in either case, what's opinions on the 80/90? mix?.

Flowki said:

As I learn more about cobs it's seems that running them above 75w? reduces efficiency.

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there is no shelf

70W is more efficient than 75

60W is more efficient than that

how hard you run them depends on your budget for gear

in general, cutting current in half increases efficiency by 10%

so 2 cobs at 45W each will be as bright as one at 100W

4 cobs at 20W each are also about as bright

Flowki said:

If running them at 75% that would, unless I'm mistaken bring them to the upper limit of what you guys think is an acceptable W to use?.

Click to expand...

theres no rule, but running cobs at 35-75W each is popular in the community. larger chips like veroC and citi 058 and luminus CXM22 all still have respectable efficiency at 100W as they each have hundreds and hundreds of diodes as opposed to a small chip like a citi1212 that has 144

The current per diode (as well as how heat dissipation is limited by how crowded together they are) are the main determinants of efficiency

also remember "100%" is completely arbitrary.

the fixture you are looking at is running the chip at ~40% of the manufacturer's max current for that chip at its top setting

Flowki said:

I hope to use 6 of these units...

If running them at 75% that would, unless I'm mistaken bring them to the upper limit of what you guys think is an acceptable W to use?.

Click to expand...

At full power each unit is 190 output watts at 46-47% efficiency, so 88 par watts each x 6 = 528 par watts / 30sq/ft = 17.6 par watts per foot. That's a pretty good flowering intensity IMO. If you drop to 75% current, 140 output watts at 51-53% efficient so 437 par watts / 30 = 14.56 par watts per foot, which is also not a bad place to be.

100% output will give you a tad over 900 PPFD while 75% will provide just under 800. These #s and the math is all rough estimates but probably pretty close. If you don't mind the electrical use and there isn't a heat problem might as well run them wide open. Either way isn't going to hit upper limits so you shouldn't feel like you need to turn them down. Put 9 of those units in there and you might want to dim a bit... not that I'm suggesting you need more than 6. If you can grow you can get really nice results with 800-900 PPFD.

Vero Cs at 75 watts with reflectors: i dont think efficiency loss of running them at 75w is a big concern over 50w. You may wanna consider light spread and intensity; if you vegg your plants under flourecents or another low intensity source you may find the plants right under the fixture wont like the high intensity light when you put them direct to flower. Make sure you do a hard vegg, idealy under the same lights and ramp up the power slowly to avoid light burn. If your in a reflective space you can remove the reflectors to avoid to much intensity and increase spread. Try what works for you
Other notes: if you wanna daisy chain the units, dont use one timer for all 6, you may blow fuses. Recomendations around here is 1 timer : 2 drivers as they pull a lot of current for a short time when they turn on.
80 / 90 cri: try half an half? Theres been a few side by sides around here with different result.
The Dawg tried citizen and 90 cri looked better but yield results looked muddied by so.ething cant remember what. Rahz did another side by side where 90 cri looked the best but again some muddying due to inadvertent extra veg time. I think he used veros but not sure. captainmorgan did quantumboards abd 90 cri came up short. Unless rahz cri test was vero i dont think anyone here tried vero 3000k 80cri vrs 90 cri. Go half an half: either do a side by side to convince yourself or do 80/90/80 etc. If you make up your mind later you can by 6 vero Cs at digikey for about 200£ and change them yourself: info on how around here or on growmau5-tv.
I think a few people around here recognize themselves in your doubts about what to get for your first setup, best thing is to get something so that you can compare and change when youve seen for yourself. Your setup looks solid from here, good chips on good heatsinks with meanwell drivers, with warranty from your own country (assuming youre from uk). Around 30w of light per square foot with possibilty to go up to 40. If you get them at preorder 235 £ you have a good deal, plug and play and the fixture looks good for 3 feet wide canopy. Happy growing and dont worry

Thank you all for the help, truly appreciated.

we run a 950 COB setup using the Vero 29c's. Our photoperiods did great the higher intensity @ ~75%, but the autoflowers we ran afterwards didn't like that intensity so we lowered to 50% and they did alright. Next year probably going a little lower than that for the autos.
they were two blue dreams, one lemon juice express and a Pakistan Ryder.