DiY LED - Cree CXA3070
- Thread starter SupraSPL
- Start date
Observe & Report
Well-Known Member
yeah, what would be great is if someone with the skills and even more time on their hands then us would whip up something in matlab/maple/mathematica or PoV that visualizes the light spread based on where you put the COBs and/or does finite element analysis to optimize COB placement. Amateur telescope makers have a program called "plop" that does FEA to calculate optimal placement of supports that evenly distribute the forces acting on the mirror.
Organix420
Member
I'm not sure if this is in the ballpark of what you mean but I did some paper math using the law of cosines. I was able to figure out how high the plants can get on the outside before they are officially out of the viewing angle if the light is exactly 12in above the plants. turns out the outer most plants can only get 4in taller but Im in scrogg so good deal for me
Anyway thats one method!
Observe & Report
Well-Known Member
The take home is once you figure out how which chip and how much total flux you need, you spread it out over as many COBs as possible. For the same output, more and bigger COBs means more efficient light spread more evenly. The catch is that it costs more up front. So you take capital expenditure and assembly costs (more cobs = more wiring, drilling, tapping etc...) and balance them against long term energy use and loss of yield from having the light drop off on the edges, taking into account the fact that you'll be able to get COBs that are much more efficient in 3-5 years.
hyroot
Well-Known Member
that would be Chaz's area of expertise.
Positivity
Well-Known Member
I dunno..I wanna run it at max. Been waiting years for leds to have some good penetration. Cxa 3590 150w with a nice reflector and a dimmer. I'll take the efficiency loss if it hits the ground hard hps style and dim it when I'm feeling frugal.
pepperdust
Well-Known Member
my idea is a 300-350 watt in a reflector .. 9-12 pieces.. problem I'm coming up with is reds and tying in the heatsink to the top of the reflector or put it in a reflector and air cool..
drilling a bunch of holes and getting correct placement would be hard for me.. then getting it to sit flush means wiring all inside the hood, as any gap is gong to do stray light on the top of the reflector.. then also it might never sit flush with holding the led down,, only epoxy or whatever glue you use is the only option I can think of right now to get it to match up and sit flush on the top of the reflector / heatisnk
SupraSPL
Well-Known Member
To clarify the numbers in those charts, when Mr Flux calculated the CXA numbers he was not using the CXA3070 and he did not specify which bin so the lumen/W, efficiency, and flux would not be correct figures. Same goes for the Vero, the numbers would vary depending on which Vero you are runnning. To make it more complicated, the numbers would have to be adjusted depending on the current you are running. Also, there would need to be an adjustment for junction temp.
So the constants are LER and photons/PAR WATT, which should apply to all the CXAs of that particular color temp. That is very useful because it allows us to calculate the actual efficiency at a given current and Tj for any model of CXA of that color temp.
So in the example below with (4) CXA3070s on a heatsink running at 1A, if we have 58 PAR WATTS of CXA 3000K, we get 4.88 umol/s per PAR WATT for a total of 283 umol/s. So if you can fit 4 modules in a 3X3 you get 1131 umol/s/m2 (PPFD)
SupraSPL
Well-Known Member
Organix420, interesting drivers thanks for the link!
---------------------------
Positivity, we can have our cake and eat it:
I am testing modules with (4) CXA3070s running at 700mA for a total of 100W, running very cool at 43% efficiency = 43 watts of photons
If I crank them up to 1A and increase fan speed they will still be running cool at 148W and 39% efficiency = 58 watts of photons.
For comparison if we ran (1) CXA3590 at full blast (1.8A) on that same heatsink it would dissipate 150W at 28.4% efficient = 43 watts of photons.
If we ran (3) CXA3590 at 700mA on the same heatsink dissipation would be 153W at 42% efficient = 64 watts of photons
So the most intense light possible can also correlate with the highest electrical efficiency, the trade off being a somewhat higher up front cost.
------------------
Regarding penetration/reach/intensity, the way I see it, a pair of the high efficiency heatsinks (120 watts of photons) will replace a 600HPS. The 600 HPS is 36% efficient when brand new but average lifetime efficiency of the bulb might be 32% so we get 192 watts of photons. The problem with HPS photons is that they are shooting everywhere and often through glass, so if only 70% of them get to the canopy we are down to 135 watts of photons and they are somewhat the wrong color.
So if we agree that a pair of the 150W LED heatsinks can put just as much light into the canopy as a 600HPS, the next thing is to recognize that the heatsinks can get much closer to the canopy which can increase the light intensity much higher than HPS and more of the photons actually make it into the canopy without the need for reflectors/lenses etc. Amazing, and as the efficiency of COBs increases they will redefine the way growing is done
---------------------------
Positivity, we can have our cake and eat it:
I am testing modules with (4) CXA3070s running at 700mA for a total of 100W, running very cool at 43% efficiency = 43 watts of photons
If I crank them up to 1A and increase fan speed they will still be running cool at 148W and 39% efficiency = 58 watts of photons.
For comparison if we ran (1) CXA3590 at full blast (1.8A) on that same heatsink it would dissipate 150W at 28.4% efficient = 43 watts of photons.
If we ran (3) CXA3590 at 700mA on the same heatsink dissipation would be 153W at 42% efficient = 64 watts of photons
So the most intense light possible can also correlate with the highest electrical efficiency, the trade off being a somewhat higher up front cost.
------------------
Regarding penetration/reach/intensity, the way I see it, a pair of the high efficiency heatsinks (120 watts of photons) will replace a 600HPS. The 600 HPS is 36% efficient when brand new but average lifetime efficiency of the bulb might be 32% so we get 192 watts of photons. The problem with HPS photons is that they are shooting everywhere and often through glass, so if only 70% of them get to the canopy we are down to 135 watts of photons and they are somewhat the wrong color.
So if we agree that a pair of the 150W LED heatsinks can put just as much light into the canopy as a 600HPS, the next thing is to recognize that the heatsinks can get much closer to the canopy which can increase the light intensity much higher than HPS and more of the photons actually make it into the canopy without the need for reflectors/lenses etc. Amazing, and as the efficiency of COBs increases they will redefine the way growing is done
tallen
Well-Known Member
Awesome info Supra, I love the way you explain things. A lot of this stuff is still a little over my head but you explain things in a way that I can understand what your saying even if I don't know how to apply it yet.
I did read Mr Flux's Cree Analysis thread but a lot of that was still over my head too. When I inquired about PAR #'s and spread I was thinking more along the lines of the testing growers house does or what Area51 did with their own lights (how much light is actually hitting the canapy at a given distance from the source)-those charts I understand and know how to compare easy enough. I know Gaius is getting a PAR meter so he'll be able to tell us what he's getting under his driven at 1.4 but it would be awesome to know how those #'s compare when they're driven softer for more efficiency.
I did read Mr Flux's Cree Analysis thread but a lot of that was still over my head too. When I inquired about PAR #'s and spread I was thinking more along the lines of the testing growers house does or what Area51 did with their own lights (how much light is actually hitting the canapy at a given distance from the source)-those charts I understand and know how to compare easy enough. I know Gaius is getting a PAR meter so he'll be able to tell us what he's getting under his driven at 1.4 but it would be awesome to know how those #'s compare when they're driven softer for more efficiency.
SupraSPL
Well-Known Member
Glad to hear and I hope it helps. Feel free to ask any questions. I will check into what A51 did. I am normally very skeptical of par measurements because their accuracy depends on the ability of the meter to measure each wavelength correctly. If I understand correctly only the really high dollar meters ($5000) can give us a genuine quantitative measurement and compare lights with different spectra. I believe those can be rented but once we know how many photons are reaching the canopy (PPFD) that still is not the whole picture because we have to take the spectra into consideration and we dont know what the best SPD is anyway lol.
One of the questions I have that a good meter could answer is, how much higher than the minimum figure is the typical CXA3070 COB? I have noticed that my COB heatsinks are running a few degrees cooler than my RWB modules which increases my suspicion that the CXA3070 is exceeding the minimum.
One of the questions I have that a good meter could answer is, how much higher than the minimum figure is the typical CXA3070 COB? I have noticed that my COB heatsinks are running a few degrees cooler than my RWB modules which increases my suspicion that the CXA3070 is exceeding the minimum.
Observe & Report
Well-Known Member
I don't know about the CXAs but at this time the Veros all have the same chips, just different quantities of them. If you look in the datasheets you'll find that the efficacy is identical for all Vero COBs at test current. So the numbers provided by Mr. Flux, which are calculated at test current, are valid no matter which Vero COB you pick.
SupraSPL
Well-Known Member
Here are the numbers I worked up for Vero 3000K. And you are correct, they are very similar at each test current step and the CXA sheets are not arranged that way.
But we would still need to know the radiometric efficiency for the current and Tj you are going to run before we can calculate ppf from Mr Flux numbers because we need to know how many PAR Watts it is emitting. The constant for Vero 3000K is: 3.49 umol/s / PAR Watt.
But we would still need to know the radiometric efficiency for the current and Tj you are going to run before we can calculate ppf from Mr Flux numbers because we need to know how many PAR Watts it is emitting. The constant for Vero 3000K is: 3.49 umol/s / PAR Watt.
PSUAGRO.
Well-Known Member
Just send your DIY panels over to growers house!!!!....lol..... they did just recently buy a spectroradiometer from stellarnet($3500)
I still don't understand their "average" par/watt calculations, because the vero cob seems low
http://growershouse.com/images/ALTEST_infographic_1.pdf the philips 315w agro-elite cmh is getting over 22 par/watt ......that's crazy #'s
I still don't understand their "average" par/watt calculations, because the vero cob seems low
http://growershouse.com/images/ALTEST_infographic_1.pdf the philips 315w agro-elite cmh is getting over 22 par/watt ......that's crazy #'s
PetFlora
Well-Known Member
Huh, my post disappeared:
Yeah, but no better than the KIND 315. WTF?
Most important to me is the numbers at the corners of 3 x 3 and there the CMH blows away the KIND
Yeah, but no better than the KIND 315. WTF?
Most important to me is the numbers at the corners of 3 x 3 and there the CMH blows away the KIND
MrFlux
Well-Known Member
"par" is not a unit and the "par per watts" doesn't make any sense. I have no clue what they could mean by that.
The metric that I like most is how many photons per second come out for every Watt going in. It is expressed in umol/J (micromol per Joule). It gives a better picture than just the radiometric efficiency, especially when high-end red diodes are used like in the Hans panel.
The Vero 4000K gives 1.87 umol/J (at default test current, 25C), the Hans panel gives 1.78, and XGS 190 gives 1.55 (beware last two figures quoted from memory)
The metric that I like most is how many photons per second come out for every Watt going in. It is expressed in umol/J (micromol per Joule). It gives a better picture than just the radiometric efficiency, especially when high-end red diodes are used like in the Hans panel.
The Vero 4000K gives 1.87 umol/J (at default test current, 25C), the Hans panel gives 1.78, and XGS 190 gives 1.55 (beware last two figures quoted from memory)
Observe & Report
Well-Known Member
The thermal part is my weakness is 25C Tj realistic for our panels? I think they get the specs by giving the board a pulse when it's cold but our lights are on for 12+ hours. If your room is 25C and your heatsink is a few degrees above that, Tj has to be much higher.
Positivity
Well-Known Member
Organix420, interesting drivers thanks for the link!
---------------------------
Positivity, we can have our cake and eat it:
I am testing modules with (4) CXA3070s running at 700mA for a total of 100W, running very cool at 43% efficiency = 43 watts of photons
If I crank them up to 1A and increase fan speed they will still be running cool at 148W and 39% efficiency = 58 watts of photons.
For comparison if we ran (1) CXA3590 at full blast (1.8A) on that same heatsink it would dissipate 150W at 28.4% efficient = 43 watts of photons.
If we ran (3) CXA3590 at 700mA on the same heatsink dissipation would be 153W at 42% efficient = 64 watts of photons
So the most intense light possible can also correlate with the highest electrical efficiency, the trade off being a somewhat higher up front cost.
------------------
Regarding penetration/reach/intensity, the way I see it, a pair of the high efficiency heatsinks (120 watts of photons) will replace a 600HPS. The 600 HPS is 36% efficient when brand new but average lifetime efficiency of the bulb might be 32% so we get 192 watts of photons. The problem with HPS photons is that they are shooting everywhere and often through glass, so if only 70% of them get to the canopy we are down to 135 watts of photons and they are somewhat the wrong color.
So if we agree that a pair of the 150W LED heatsinks can put just as much light into the canopy as a 600HPS, the next thing is to recognize that the heatsinks can get much closer to the canopy which can increase the light intensity much higher than HPS and more of the photons actually make it into the canopy without the need for reflectors/lenses etc. Amazing, and as the efficiency of COBs increases they will redefine the way growing is done
I do agree with you supra. I'd just like to have one mounted and running closer to max and run it through a test to see how it does. I like to see things running and in action before I make a final analysis. And in reality I'd probably start at 2/3 max like I did with the xmls that would probably be close enough for me without going horribly inefficient.
Kudos to all of you trying these out, much respect.
edit...was half asleep when I read that. 3 versus one 3590 putting out that much more photons. Plus better spread..lol...yah that sounds really good.