testiclees
Well-Known Member
I use the 72v (3500k), 3590 cd @ .7mA. It was the best bin available when i built my supplemental wings.
They are as effective as I had read and just what i was expecting.
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COB efficiency Spreadsheets
- Thread starter nogod_
- Start date
They are as effective as I had read and just what i was expecting.
BOBBY_G
Well-Known Member
that explanation is confusing you can also think of it this way
calc PAR W
calc PAR W/SF
PPFD = PAR W/SF *45
thats how ive always done it. note supras numbes from this famous post
https://www.rollitup.org/t/cxb3590-1500w.878136/page-2#post-11778236
my notes are in bold italics.
@45.7%
83.63 PAR W covering 5 ft² = 749 PPFD
83.63/5 = 16.73 x 45 = 752 PPFD
@49.7%
75 PAR W covering 4ft² = 840 PPFD
75 PAR W covering 5ft² = 672 PPFD
75/4= 18.75 x 45= 844 PPFD
75/5= 15 x 45 = 675 PPFD
@ 56.3%
110.3 PAR W covering 6ft² = 824 PPFD
110.3/6 X 45 = 827 PPFD
@64%
117.8 PAR W covering 6ft² = 879 PPFD
117.8 PAR w covering 7ft² = 754 PPFD
117.8/6 x 45 = 884 PPFD
117.8/7 x 45 = 757 PPFD
calc PAR W
calc PAR W/SF
PPFD = PAR W/SF *45
thats how ive always done it. note supras numbes from this famous post
https://www.rollitup.org/t/cxb3590-1500w.878136/page-2#post-11778236
my notes are in bold italics.
@45.7%
83.63 PAR W covering 5 ft² = 749 PPFD
83.63/5 = 16.73 x 45 = 752 PPFD
@49.7%
75 PAR W covering 4ft² = 840 PPFD
75 PAR W covering 5ft² = 672 PPFD
75/4= 18.75 x 45= 844 PPFD
75/5= 15 x 45 = 675 PPFD
@ 56.3%
110.3 PAR W covering 6ft² = 824 PPFD
110.3/6 X 45 = 827 PPFD
@64%
117.8 PAR W covering 6ft² = 879 PPFD
117.8 PAR w covering 7ft² = 754 PPFD
117.8/6 x 45 = 884 PPFD
117.8/7 x 45 = 757 PPFD
wietefras
Well-Known Member
Thing is, you said: "ppf =~ parW*45". To calculate PPF that 45 should be 4.47 to 4.66. You actually were calculating "par w/sqft*45".
Nothing confusing about what I proposed. Just work with umol/s instead of percentages, magical numbers and PAR W calculations.
CXB3070 BB @ 1.4A (49W) produces 110umol/s
CXB3590 CD 36V @ 1.75A (62W) produces 140umol/s
Q: I would like to replace a 1840umol/s Gavita Pro 1000W HPS (boosted). How many COBs would that take?
A: 1840 / 110 = 16.7 or 1840 / 140 = 13.1
Q: I have 8 CXB3070 BB @50W. What kind of PPFD can I expect over a 1.44m2 surface area?
A: 8 * 110 / 1.44 = 769 umol/s/m2
Nothing confusing about what I proposed. Just work with umol/s instead of percentages, magical numbers and PAR W calculations.
CXB3070 BB @ 1.4A (49W) produces 110umol/s
CXB3590 CD 36V @ 1.75A (62W) produces 140umol/s
Q: I would like to replace a 1840umol/s Gavita Pro 1000W HPS (boosted). How many COBs would that take?
A: 1840 / 110 = 16.7 or 1840 / 140 = 13.1
Q: I have 8 CXB3070 BB @50W. What kind of PPFD can I expect over a 1.44m2 surface area?
A: 8 * 110 / 1.44 = 769 umol/s/m2
ttystikk
Well-Known Member
I built the same thing as you, only I use 80 degree lenses.
testiclees
Well-Known Member
I keep toasting shit so ive been going lense-less
So with my setup and drivers i will be able to dim each cob down to 5 watts each and up to 50 watts there abouts
testiclees
Well-Known Member
shit, thats an excellent feature
BOBBY_G
Well-Known Member
well yeah i divided by SF in the next step. as i said, it was right, just not clear
ttystikk
Well-Known Member
So based on this, my 4x50W CXB3590 powered modules actually run even harder than the above numbers;
- 216W because the driver runs 8% over if the dimming leads are capped.
- 60% chip efficiency, based on some shenanigans I'll discuss soon.
- Same 6 sq ft
/6 sq ft = 21.6 PARW/sq ft
* 45 = 972 PPfD, with 80 degree lenses.
No wonder I'm having light shock problems.
testiclees
Well-Known Member
One of the mathier guys here did the calculation using the values from my set-up and the ppfd was around 1400. Broad leaved plants can not take it unless the lamp is >24", (without any uvb). Ive got my lights as high as I can get em. I'm seeing improvements in both quality and yield.
ttystikk
Well-Known Member
I'm unable to follow suit, but I'm not at all sure I need to. You see, I'm running several of the very same modules in my nursery, lenses and all. My lil veg girls are eating it up and growing like mad. This tells me to look elsewhere for the source of the problem. I've zeroed in on boosting PPfD in my big veg stages where I'm still using HID, in this case 315W CMH lights hung vertical bare bulb style. They're producing less than 1/6th the PPfD so I added another light.
I just double checked; lamp to leaf distances are the same in both places.
JorgeGonzales
Well-Known Member
Everybody should stick to umols, PPF, PPFD. It would cause a lot less confusion around here. @churchhaze would disagree. Of course, actually knowing those numbers is next to impossible, so. Maybe not.
ttystikk
Well-Known Member
I second this motion. I propose PPfD as it's a measure related to both area and PAR.
testiclees
Well-Known Member
Bro good point. I may have found that plants in much larger pots dont suffer the same irradiance beat down.
I can test it soon. Ive got a white nightmare vegging outdoors, one gal pot. Just before her trip to the flower room im gonna drop her into a 10 . Im wondering if shes well acclimated to high irradiance and luxurious soil will i see phytotoxicity???
JorgeGonzales
Well-Known Member
Well, umols/s is the mother measurement, truncated to 400-700nm you get PPF, divided by meters you get PPFD. Efficiency as PPF/W, etc.
Apologies if this is obvious or something. It's certainly been said many, many times before.
But then it becomes as simple as saying "OK my 50W cob makes 128 PPF", multiply by 4 over 6 sq ft, and there is your 919 theoretical PPFD before losses, to use your lights as an example.
churchhaze
Well-Known Member
I do disagree. That'd be like saying people should measure the amount of gas they put in their car in moles of octane. Given a constant SPD, umol/s and W mean the same thing. Trying to tweak umol/s while W stays the same means compromising SPD.
You're tricking yourself if you really think that umol/s is somehow more accurate than W. (Tricking yourself away from your original SPD).
People who insist that ppf matters the most miss the point that it's MORE LIGHT that matters the most, and higher ppf for a given SPD means more light. PPF and power tell you the exact same thing unless you're playing GAMES with SPD. (trying to beat the system)
The only reason I can see to convert W to umol/s at all is the thrill of taking the time on an extra step.
Edit: If ppf is the "true" measurement of total light while power is an inferior measurement, please grow with only 660nm (low energy photons) leds and tell me what happens. It should be obvious in this edge case that what the lamp is lacking is not ppf, but POWER (blue and other wavelengths higher energy than 660nm given the same ppf implies more total power).
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JorgeGonzales
Well-Known Member
Well, I think it's more like dollars and donuts. Dollars are watts, donuts are photons, and I want to know how many donuts I can buy for a buck. And whether it's a donut hole or a Homer-sized novelty donut, one electron is what you get for it.
I mean as far as I know one photon equals one electron, and that's all plants care about. Is this wrong?
I mean as far as I know one photon equals one electron, and that's all plants care about. Is this wrong?
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churchhaze
Well-Known Member
Why doesn't the power company sell us electrons per second? Why do we even use units of power in the first place? Watts are interchangable between systems. Electrons are not..
The whole point of using power as units is because that's what we're concerned about as consumers. It's why doctors don't measure the amount of donuts you can eat, but instead use calories per day, a unit of power.
resinhead
Well-Known Member
Alright. You guys are throwing a lot of fancy lingo down and obviously know what your talking about.
Could I get away with rocking 3 of the 300 watt 6 cob timber fixtures in a 4x8 tent? Or will I need 4 or 5 kits? With LED it seems it's not about watts per sf, and I don't understand all of the conversions.
Could I get away with rocking 3 of the 300 watt 6 cob timber fixtures in a 4x8 tent? Or will I need 4 or 5 kits? With LED it seems it's not about watts per sf, and I don't understand all of the conversions.
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JorgeGonzales
Well-Known Member
But...plants don't care how many calories are in the donut. It's why biologists count photons and use quantum sensors, and not energy.
Yes, they are similar answers to the same question, but PAR watts is an approximation, photon flux is the exact number. I'd be ticked if my power company used an approximation.
End of the day, if I have two white leds, and one has higher efficiency, higher PAR watts, but is actually producing less photosynthetically useful output, how is that helping clear things up? PAR watts make my head hurt.
Happily this is the least important "argument" ever
Does that actually work? Emoji? Huh.