Adding deep & far reds to Quantum Board build

[Randomblame]

Source for those conversion numbers? The numbers I have heard are a bit different - 72 gets you within 10% at 3000k/3500/4000K and 69 gets you within 5% at 2700K. I think 65 and 62 sound a bit generous...

CRI90 # are from lx : μMol/s/m² conversion thread..
I have already taken the less optimistic values. Some use 57 for 2700k/CRI90 but this is simply not true.

 

[tazztone]

Some use 57 for 2700k/CRI90 but this is simply not true.

the user LivingLight at LG forum calculated speficially for vesta:


i am not grasping everything but when i multiply the lm/W of each strip by the "lm to photon conversion factor" i get this:
129 lm/W * 0.0175 = 2.26 VESTA 2700K CRI90 (0%)
135 lm/W * 0.0169 = 2.28 VESTA 5000K CRI90 (+1%)
144 lm/W * 0.0173 = 2.49 LM561C 2700K CRI90 (+9%)
175 lm/W * 0.0145 = 2.54 EB gen2 3000K CRI80 (+11%)
178 lm/W * 0.01485 = 2.64 F-Series 3000K CRI80 (+14%)
umol/s per watt
still cutting off some far red here, but only upwards of 750nm, not at 700nm like PPF-spectrum-range would.

F-series vs VESTA (at 25°C & 49.6W):
F564B: 131 umol/s (Samsung LED engine calculator to match 49.6W and 25°C)
VESTA: 55 umol/s from 2700K LEDs and 56 umol/s from 5000K
Totalling 112 umol/s.
photon output difference between VESTA and F564B 3000K is 17%.
the price difference on digikey is 61%
or 56% for 10pcs
or 50% for 25pcs
Vesta gets you double the amount of photons per dollar.
but YPF (mcCree) is 18% lower

only problem is: the VESTA specs may have been taken using pulsed light while Samsung may have used continuous light.

Livinglight has made a combined graph and calculated YPF:

(PS: price is 10.7$)

 

[Randomblame]

Nice find!
Seems my estimated numbers at half current are not so far off at all from this calculations.
~2,2μMolJ at nom. current and ~2,4 with half is not too shabby.
Samsung strips with additional deep- and far-red would be more efficient for sure, but the price point is not easily beatable. Okay, 12% more electricity adds up quickly, at least with high energy costs.
But where electricity is cheap upfront costs matter sometimes more and not to forget, there are only a few suitable CRI90 strips currently available.

 

[nfhiggs]

Vesta gets you double the amount of photons per dollar.

LOL - no. not really. Because I can run the Samsungs at 1800 mA, and STILL be more efficient AND make twice the photons per strip. You keep wanting to ignore that 15% efficiency difference as if its nothing - the harder you drive those Vesta's, the farther back you get efficiency-wise. Its like starting a race from behind when you're in a slower car. There really is no way of catching up.

If it was simply about photons per dollar, then two dollar 100W Chinese cobs putting out 10K lumens from ebay would take the crown wouldn't they?

The Vestas are cheaper, but they are less efficient - that's it.. They are not the be-all end-all you make them out to be.

 

[OneHitDone]

LOL - no. not really. Because I can run the Samsungs at 1800 mA, and STILL be more efficient AND make twice the photons per strip. You keep wanting to ignore that 15% efficiency difference as if its nothing - the harder you drive those Vesta's, the farther back you get efficiency-wise. Its like starting a race from behind when you're in a slower car. There really is no way of catching up.

If it was simply about photons per dollar, then two dollar 100W Chinese cobs putting out 10K lumens from ebay would take the crown wouldn't they?

The Vestas are cheaper, but they are less efficient - that's it.. They are not the be-all end-all you make them out to be.

What about spectrums though?
Isn't the Vesta a much broader spectrum?
I admittedly haven't dug through the data sheet but are the Vesta's 2 K temps in one strip or cob? 2700K and 5000K individually controllable?

 

[SSGrower]

What about spectrums though?
Isn't the Vesta a much broader spectrum?
I admittedly haven't dug through the data sheet but are the Vesta's 2 K temps in one strip or cob? 2700K and 5000K individually controllable?

I kinda think when we are talking white leds the need is for specific peaks in red blu and uv to suppliment the broad white spectrum. Then those spectra can be triggered at the desired time of day or days of cycle independent of the white light source.

I think these are neat strips and probaby would do a fine job but myself would lean towards the apparent effeciency advantage of the samsungs.

 

[nfhiggs]

What about spectrums though?
Isn't the Vesta a much broader spectrum?
I admittedly haven't dug through the data sheet but are the Vesta's 2 K temps in one strip or cob? 2700K and 5000K individually controllable?

Its a little heavier on the red side - but like I said earlier - it doesn't make any sense to me to trade overall efficiency for a little more red, when you can just supplement higher efficiency white LEDs with a few high efficiency red LEDs and sacrifice nothing.

 

[OneHitDone]

Its a little heavier on the red side - but like I said earlier - it doesn't make any sense to me to trade overall efficiency for a little more red, when you can just supplement higher efficiency white LEDs with a few high efficiency red LEDs and sacrifice nothing.

From a total efficiency standpoint, in your opinion would it be best to blend a hight K chip like a 6500K with hight efficiency reds vs a warm chip like a 3000 or 3500?
If I understand correctly the warmer the emitted spectrum the more conversion the phosphor is doing and the higher the efficiency loss?

 

[nfhiggs]

From a total efficiency standpoint, in your opinion would it be best to blend a hight K chip like a 6500K with hight efficiency reds vs a warm chip like a 3000 or 3500?
If I understand correctly the warmer the emitted spectrum the more conversion the phosphor is doing and the higher the efficiency loss?

IMO, the efficiency loss is mostly just the biasing of lumen values - the higher temps have more greens which biases the lumen values upward. If you were to look at the same manufacturers LEDs at differing spectrums (561C's for example), you would *most likely* find very similar PPF values, which ignores the wavelengths and just counts photons. I'm not up on the math to do such conversions, but I bet @alesh could look at some LM561C spectrums and tell us if I'm correct or not.

 

[tazztone]

I can run the Samsungs at 1800 mA, and STILL be more efficient AND make twice the photons per strip.

if you run one F564B at 1.8A u would make 204 umol/s (at an efficiency of 2.35). *assumed 50°C.

comparing this to two vestas: they would emit 224 umol/s (at efficiency of 2.27)
in this scenario two Vestas give you 10% more photons at 3.5% lower efficiency while saving you 6$ compared to one F564B.

plus you would probably damage your F-strips faster because they run hotter.

 

[Randomblame]

@OneHitDone That's LM561c/CRI80 numbers @wietefras posted in another thread a few weeks back. Like you can see, the colder colour temps offer higher electrical efficieny but the warmer spectrums deliver higher YPF/w numbers.

Although this means that warmer spectra are more appropriate, this does not mean that CRI90 would beat CRI80. On the other hand, CRI90 does not necessarily produce fewer photons, but they are outside the measurement range (400-700nm) and how far these wavelengths drive growth is hard to say. However, it can be assumed that the leaf temperatures are slightly higher due to the higher far-red content and this can help to make the plants work more efficiently. It should be easier to get the desired leaf temps of 82-86°F with higher CRI's.
That would explain why we have seen some even better results with CRI90.
Higher leaf temperature with identical light density = faster photosynthesis through better light utilization.
But I have nothing to prove it scientifically.
But it would be interesting to make a test and compare the leaf temperatures below CRI80 and CRI90. I mean a test watt vs. watt, not with identical PPFD!
Maybe someone has already done this tests...?

 

[tazztone]

Maybe someone has already done this tests...?

they have done it :

 

[OneHitDone]

Its a little heavier on the red side - but like I said earlier - it doesn't make any sense to me to trade overall efficiency for a little more red, when you can just supplement higher efficiency white LEDs with a few high efficiency red LEDs and sacrifice nothing.

From a total efficiency standpoint, in your opinion would it be best to blend a hight K chip like a 6500K with hight efficiency reds vs a warm chip like a 3000 or 3500?
If I understand correctly the warmer the emitted spectrum the more conversion the phosphor is doing and the higher the efficiency loss?

they have done it :

That is excellent information there. Far red is something that has been on my mind a lot lately with some led experiments I have been doing.

Would you have any simple way to put into perspective the Far Red : Red ratio's they are discussing in that paper? I mean, how does your standard 3000K Samsung chip stack up against that test treatment?

 

[Randomblame]

they have done it :

I see, you have yourself well prepared! I like that!
I will study it in detail later when I have more time. Unfortunately, it does not say that the effects apply 1: 1 to all plant species, because we also know from other studies that wavelengths of 730nm are strongly reflected and thus C. can be identified from the air. But that does not mean it is not useful.

 

[wietefras]

On the other hand, CRI90 does not necessarily produce fewer photons, but they are outside the measurement range (400-700nm)

CRI90 does produce less light even over the whole range. That's the inevitable loss you get from the stokes shift. Converting light to other frequencies always comes at a loss.

That would explain why we have seen some even better results with CRI90.

I have indeed seen people here claim/argue they had better results with CRI 90 when in fact the yield was a lot less. So then they went with, "yeah but the grow lasted shorter". Still they yielded significantly less and by that much that it's more economical to just add a week to your grow and yield more.

Either way, the effects of different SPDs are incredibly marginal when you account for everything. Well inside margins of "error" for the consistency of hobby grows. It's not the holy grail people like to believe it is.

 

[Randomblame]

Yepp, the beneficial effects off adding far-red are lower with increased PPFD. There is no improvments above 800μΜol/s but it's huge with lower intensities(200μMol/s/m²), at least for lettuce.
At the usually high densities we use it seems not useful to add far-red.
While the paper says that even at higher intensities it helps to balance the excitation states between PSI and PSII, but the resulting acceleration seems more to shorten the maturation time, at least for Cannabis, which in the end results in less yield per grow. You only see an increase if you can save enough weeks per year for an extra grow and even then, you can not sure that you will exceed CRI80's annual results.

I'm using ⅔ 3k/CRI80 f-strips and ⅓ 3k/CRI90 COB's right now and my plants seems to grow better than ever but this is most probably because of the strips. They look less stressed, especially at the end of the day.

 

[Schalalala]

CRI90 does produce less light even over the whole range. That's the inevitable loss you get from the stokes shift. Converting light to other frequencies always comes at a loss.

Thanks for pointing that out.

IT IS ALL ABOUT THE AMOUNT OF PHOTONS! Check the reaction equation of photosynthesis and read up on both photosystems.

660 nm does nothing magical except driving photosynthesis.

A 660 nm photon just has the minimal amount of energy needed for the photo reaction and therefore it makes sense to use photons with this wavelength IF your light source can produce exactly these photons.

Example: Out of one watt of energy, you can produce 5.6 µmol of photons with an wavelength of 660 nm. If you would split this watt in photons with an wavelength of say... 605 nm, you just get 5.09 µmol out of it. So, which one do you use?
Probably the 660 nm light source.

The thing is, a phosphor converted LED produces blue photons (1 W = 3.7 umol @ 450 nm). These photons then hit the phosphor molecules and get radiated from there with longer wavelength (=less energy). The difference of these two energy levels is the stokes shift and is lost as heat! Surely there are cheaper ways to create heat then using LEDs.

So if you had an 100% efficient blue LED and convert 100% of these photons to 660 nm, the LED would put out 3.7 µmol. (Compare that with an 100% efficient hyper red -> 5.6 µmol!)

So from a energetic point of view you can say: The less conversion you do, the better it is. The bigger the difference of the wavelengths are, the worse it gets.

In an hyper red (660 nm) LED there is NO conversion loss as it produces the most usable photons right from the beginning!

Why usable?
Because both photo systems can use them! They need AT LEAST 680 nm and 700 nm to work (COMMON MISCONCEPTION OF THE EMERSON EFFECT*!!). Photons with shorter wavelength (more energy) work just fine - the surplus of energy (again) gets radiated as heat (this time) via the leafs.


So in regard of CRI90 and photosynthesis: The plant gives a fuck whether it gets 660 or 610 nm photons (look up RQE and absorption charts!)!
In regard of far red: If you want far red, then buy far red LEDs and don't waste all his energy in the phosphor layer.

*
Deliver plants just photons with 700 nm -> one of two photo systems are active.
Deliver photons with 680 nm -> both work, and they work together which boosts efficiency further (again, look up the Wikipedia article of photosynthesis)
100 dollar question: How many photo systems work with a standard CRI80 spectrum?

 

[OneHitDone]

Thanks for pointing that out.

IT IS ALL ABOUT THE AMOUNT OF PHOTONS! Check the reaction equation of photosynthesis and read up on both photosystems.

660 nm does nothing magical except driving photosynthesis.

A 660 nm photon just has the minimal amount of energy needed for the photo reaction and therefore it makes sense to use photons with this wavelength IF your light source can produce exactly these photons.

Example: Out of one watt of energy, you can produce 5.6 µmol of photons with an wavelength of 660 nm. If you would split this watt in photons with an wavelength of say... 605 nm, you just get 5.09 µmol out of it. So, which one do you use?
Probably the 660 nm light source.

The thing is, a phosphor converted LED produces blue photons (1 W = 3.7 umol @ 450 nm). These photons then hit the phosphor molecules and get radiated from there with longer wavelength (=less energy). The difference of these two energy levels is the stokes shift and is lost as heat! Surely there are cheaper ways to create heat then using LEDs.

So if you had an 100% efficient blue LED and convert 100% of these photons to 660 nm, the LED would put out 3.7 µmol. (Compare that with an 100% efficient hyper red -> 5.6 µmol!)

So from a energetic point of view you can say: The less conversion you do, the better it is. The bigger the difference of the wavelengths are, the worse it gets.

In an hyper red (660 nm) LED there is NO conversion loss as it produces the most usable photons right from the beginning!

Why usable?
Because both photo systems can use them! They need AT LEAST 680 nm and 700 nm to work (COMMON MISCONCEPTION OF THE EMERSON EFFECT*!!). Photons with shorter wavelength (more energy) work just fine - the surplus of energy (again) gets radiated as heat (this time) via the leafs.


So in regard of CRI90 and photosynthesis: The plant gives a fuck whether it gets 660 or 610 nm photons (look up RQE and absorption charts!)!
In regard of far red: If you want far red, then buy far red LEDs and don't waste all his energy in the phosphor layer.

*
Deliver plants just photons with 700 nm -> one of two photo systems are active.
Deliver photons with 680 nm -> both work, and they work together which boosts efficiency further (again, look up the Wikipedia article of photosynthesis)
100 dollar question: How many photo systems work with a standard CRI80 spectrum?

Great information!

Do you have any links for information that talks about breaking an SPD's down to umol per nm?

 

[Schalalala]

Search for "The math behind" thread by @alesh . You need a Digitizer (https://automeris.io/WebPlotDigitizer/), Excel and a lot of time. This stuff is complicated. (If you calculate with LER/QER, take the time to calc by hand and write down the units! This really helped me a lot in understand it properly.)

 

[tazztone]

the beneficial effects off adding far-red are lower with increased PPFD. There is no improvments above 800μΜol/s

they only tested to 800. but the graph would go on.



also note this other excerpt from the study i linked before: