Cob drive amperage & effective penetration

N

Nugtorrent

Member
Hi guys, first time poster on these forums. I've been studying up on what I want for my first build but had one question regarding driver amperage & canopy penetration.

Has anyone found a particular Mean Well (700ma, 1050ma, 1400ma) that is hitting the sweet spot in terms if dense fully formed buds below 10-12 inches? I realize running 8x CXB 3590's on a 700ma driver saves me 5-10% efficiency at the wall, but if I'm able to obtain an extra 6-12 inches of effective par running at the higher current, that could really effect my yield (In particular I was looking to set up Growmau5's design with 3x 36" 5.88" aluminum heat sinks, 4x 3590's per bar with 2x HLG 240H-C1050B)

I want to not only focus on G/W but also G/SqFt, since I will be limiting the environment to 4'x4'. Running 400w over huge sq/footage with a shallow scrog works, but I've found with my MarsHydro's I have to overpower a tent with true wattage to come close to HPS yields in equal square footage environments. A 2x4 running three Mars2 400's @ 555 true watts grows amazing bud and yields fantastic (11 oz off one plant my last harvest , glimpse @ 37f https://imgur.com/a/mvfAn#GOGdCJb ) but the G/W is abysmal. I wanna replicate this obviously lol but much more efficiently.

Thanks for the replys.
 
HydoDan

HydoDan

Well-Known Member
From what I understand 1400ma (50w) is supposedly the sweet spot between efficiency and production..
At least that is what I was told.. I'm sure we'll find out!
 
wietefras

wietefras

Well-Known Member
Light penetration has nothing to do with amperage. It depends mostly on the total amount of light.

8x CXB3590 @ 700mA will give you roughly the same amount of light as 4x CXB3590 @1400mA (couple percent more due to higher efficiency). Since teh amount of light is the roughly the same you will get the same light intensities lower down and thus the "penetration" is pretty much the same too.
 
MeGaKiLlErMaN

MeGaKiLlErMaN

Well-Known Member
Nugtorrent said:
Hi guys, first time poster on these forums. I've been studying up on what I want for my first build but had one question regarding driver amperage & canopy penetration.

Has anyone found a particular Mean Well (700ma, 1050ma, 1400ma) that is hitting the sweet spot in terms if dense fully formed buds below 10-12 inches? I realize running 8x CXB 3590's on a 700ma driver saves me 5-10% efficiency at the wall, but if I'm able to obtain an extra 6-12 inches of effective par running at the higher current, that could really effect my yield (In particular I was looking to set up Growmau5's design with 3x 36" 5.88" aluminum heat sinks, 4x 3590's per bar with 2x HLG 240H-C1050B)

I want to not only focus on G/W but also G/SqFt, since I will be limiting the environment to 4'x4'. Running 400w over huge sq/footage with a shallow scrog works, but I've found with my MarsHydro's I have to overpower a tent with true wattage to come close to HPS yields in equal square footage environments. A 2x4 running three Mars2 400's @ 555 true watts grows amazing bud and yields fantastic (11 oz off one plant my last harvest , glimpse @ 37f https://imgur.com/a/mvfAn#GOGdCJb ) but the G/W is abysmal. I wanna replicate this obviously lol but much more efficiently.

Thanks for the replys.
Click to expand...
I really wish I could find the chart I originally saw regarding penetration... It said something like 850PPF was enough to penetrate properly... Change that to PPFD and you're golden.
 
CobKits

CobKits

Well-Known Member
MeGaKiLlErMaN said:
I really wish I could find the chart I originally saw regarding penetration... It said something like 850PPF was enough to penetrate properly... Change that to PPFD and you're golden.
Click to expand...
that doesnt really correlate

a large fluorescent array can put out 850 ppf, as well as an HPS.

"penetration" (the ability to have useful amounts of light below canopy) is almost entirely a function of distance from canopy. the sun is practically infinitely far away from us and so has perfect penetration. light intensity at top of canopy is the same as at the bottom of the plant.

A T12 fluorescent can get you appropriate intensity at top of canopy but is generally 2" above the tops and thus has poor penetration because the ratio of the distance from the light to the bottoms vs the distance from the light to the tops is too high. if you go 18" down thats 9x the distance (see inverse square law)

a 1000W HPS needs to be 36" from canopy to deliver proper light levels at canopy. 18 inches into your canopy you havent even doubled your distance from the light source and will still have strong light.

if your COBs arent penetrating - run them hotter or add more, and then raise them up. this will reduce the gradient of intensity from the tops of your plants to the bottoms. In an ideal world wed all have 12' ceilings and be running an efficient 50 W/SF hung high and growing 36" colas all day long
 
MeGaKiLlErMaN

MeGaKiLlErMaN

Well-Known Member
CobKits said:
that doesnt really correlate

a large fluorescent array can put out 850 ppf, as well as an HPS.

"penetration" (the ability to have useful amounts of light below canopy) is almost entirely a function of distance from canopy. the sun is practically infinitely far away from us and so has perfect penetration. light intensity at top of canopy is the same as at the bottom of the plant.

A T12 fluorescent can get you appropriate intensity at top of canopy but is generally 2" above the tops and thus has poor penetration because the ratio of the distance from the light to the bottoms vs the distance from the light to the tops is too high. if you go 18" down thats 9x the distance (see inverse square law)

a 1000W HPS needs to be 36" from canopy to deliver proper light levels at canopy. 18 inches into your canopy you havent even doubled your distance from the light source and will still have strong light.

if your COBs arent penetrating - run them hotter or add more, and then raise them up. this will reduce the gradient of intensity from the tops of your plants to the bottoms. In an ideal world wed all have 12' ceilings and be running an efficient 50 W/SF hung high and growing 36" colas all day long
Click to expand...
I would tend to disagree, main reason is that someone one here beat a de Gavita (1000W) with T5... Same area same everything.cof course I could very well be wrong and that's ok, but if you get more photons on the plant regardless of the total PPF output... The PPFD seems to mean more in the grand scheme. So closer light with more LESs will always beat out a single high intensity surface. A generalization that could be incorrect given specific ser instances but overall That's pretty sound IMO

This was the closest one I could find on light attenuation...

http://cdn.intechopen.com/pdfs-wm/28377.pdf
 
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CobKits

CobKits

Well-Known Member
MeGaKiLlErMaN said:
I would tend to disagree, main reason is that someone one here beat a de Gavita (1000W) with T5.
Click to expand...
because one light "beat" another has nothing to do with penetratin in regard to the laws of physics as described above. a light meter will demonstrate this time and time again.

MeGaKiLlErMaN said:
The PPFD seems to mean more in the grand scheme.
Click to expand...
its everything.... ppf is just a means for getting your desired ppfd
MeGaKiLlErMaN said:
So closer light with more LESs will always beat out a single high intensity surface.
Click to expand...
not necessarily. lots of variables. uniformity of coverage and penetration being the two big ones (assuming similar spectra). in essence penetration is just vertical uniformity of coverage.....
 
N

Nugtorrent

Member
Wow guys really stoked on the feedback, wasn't expecting such an active community!

I suppose Cobkits hit the nail on the head with the Inverse Square Law, that was more what I meant by penetration. I have tested my home grow with a PAR meter from work, and managed 1200 at the top of my canopy,4-500 at 14" below the lights. This drops drastically to the low hundreds at a mere three feet. In contrast to a 1000DE Gavita, we tested those at 1k at top of canopy, but 6-700 par a good 3-4 feet down into the aisle.

I understand there are tons of variables when it comes to canopy penetration, the inverse square was what I was looking for. For the sake of this example, lets pretend the tent is empty and we are reading PAR from the ground, and the lights mounted at different heights. 8x CXB @ 700ma vs 4 CBX @ 1.4a. Yes the effective light is the same (ignore the slight efficiency for the sake of ease), will I get the same PAR reading from 5ft off the ground with the two? If my understanding of the law is correct, the total light is irrelevant; Its the initial intensity of the light source (from a quick wikipedia read) and the distance that matters. So yes the 700ma will put out the same if not more lumens than the 1.4a, but the 1.4a will have light that carries deeper. Comparing a T5 to a HPS would seem to support this, as they can have equal wattage and vastly different effective flowering penetration.

For my build this was the final deciding factor. the 700ma build is super attractive because of the efficiency at the wall, but damn considering the increased upfront cost on parts I question whether that outweighs the increased weight deep into the canopy the higher intensity can afford. But fuck me there are twice as many light sources with the 700ma lol this is ultra stoney
 
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PhotonFUD

PhotonFUD

Well-Known Member
~400 umols (as per Abiqua) at the leaf surface.

Get a PAR meter and use it. That should be the only correct answer.
 
V

VegasWinner

Well-Known Member
If production is first PPFD is the solution. Focus on a PPFD 800 and above is best. Over 1200 PPFD is a waste of money. 50w/sf will give you the most efficient PPFD. peace
 
HydoDan

HydoDan

Well-Known Member
Nugtorrent said:
Wow guys really stoked on the feedback, wasn't expecting such an active community!

I suppose Cobkits hit the nail on the head with the Inverse Square Law, that was more what I meant by penetration. I have tested my home grow with a PAR meter from work, and managed 1200 at the top of my canopy,4-500 at 14" below the lights. This drops drastically to the low hundreds at a mere three feet. In contrast to a 1000DE Gavita, we tested those at 1k at top of canopy, but 6-700 par a good 3-4 feet down into the aisle.

I understand there are tons of variables when it comes to canopy penetration, the inverse square was what I was looking for. For the sake of this example, lets pretend the tent is empty and we are reading PAR from the ground, and the lights mounted at different heights. 8x CXB @ 700ma vs 4 CBX @ 1.4a. Yes the effective light is the same (ignore the slight efficiency for the sake of ease), will I get the same PAR reading from 5ft off the ground with the two? If my understanding of the law is correct, the total light is irrelevant; Its the initial intensity of the light source (from a quick wikipedia read) and the distance that matters. So yes the 700ma will put out the same if not more lumens than the 1.4a, but the 1.4a will have light that carries deeper. Comparing a T5 to a HPS would seem to support this, as they can have equal wattage and vastly different effective flowering penetration.

For my build this was the final deciding factor. the 700ma build is super attractive because of the efficiency at the wall, but damn considering the increased upfront cost on parts I question whether that outweighs the increased weight deep into the canopy the higher intensity can afford. But fuck me there are twice as many light sources with the 700ma lol this is ultra stoney
Click to expand...
Split the difference and run 1050ma. Compromise!
 
nogod_

nogod_

Well-Known Member
This makes no sense to me.

What about achieving the same ppfd (not ppf) with T5s at 12" vs HPS at 6'? which has better penetration?

If you have the same density, the distance those photons travelled shouldnt matter.

What does matter is the different wavelengths of light present and whether or not the photons have a direct path to the interior of your canopy.

Green light is largely reflected so there is a good chance a lot of those photons will bounce off the first leaf they hit and end up elsewhere. If you have a heavily green-weighted spectrum expect great "penetration".

The rest of the PAR spectrum has to reach the lower branches of your plant directly either through diffusion or by bringing the light source to the place its needed (intercanopy lighting).

Again: if you have the same ppfd using 64 emitters vs 16, expect better penetration with more emitters(diffusion).

CobKits said:
that doesnt really correlate

a large fluorescent array can put out 850 ppf, as well as an HPS.

"penetration" (the ability to have useful amounts of light below canopy) is almost entirely a function of distance from canopy. the sun is practically infinitely far away from us and so has perfect penetration. light intensity at top of canopy is the same as at the bottom of the plant.

A T12 fluorescent can get you appropriate intensity at top of canopy but is generally 2" above the tops and thus has poor penetration because the ratio of the distance from the light to the bottoms vs the distance from the light to the tops is too high. if you go 18" down thats 9x the distance (see inverse square law)

a 1000W HPS needs to be 36" from canopy to deliver proper light levels at canopy. 18 inches into your canopy you havent even doubled your distance from the light source and will still have strong light.

if your COBs arent penetrating - run them hotter or add more, and then raise them up. this will reduce the gradient of intensity from the tops of your plants to the bottoms. In an ideal world wed all have 12' ceilings and be running an efficient 50 W/SF hung high and growing 36" colas all day long
Click to expand...
 
OLD MOTHER SATIVA

OLD MOTHER SATIVA

Well-Known Member
isn't penetration the result of raw power....ie one cob@150 will penetrate way more than 3 @ 50?

and is ppf is one reading over one particular area and ppfd is the total averaged over the area?
 
KarmaPaymentPlan

KarmaPaymentPlan

Well-Known Member
OLD MOTHER SATIVA said:
isn't penetration the result of raw power....ie one cob@150 will penetrate way more than 3 @ 50?

and is ppf is one reading over one particular area and ppfd is the total averaged over the area?
Click to expand...
150w doesnt mean that its comes out the emitter stronger just more dense is my understanding
3 @ 50w would generate more light and from more areas leading to better penetration IMO
 
OLD MOTHER SATIVA

OLD MOTHER SATIVA

Well-Known Member
..we are talking about penetration aren't we..not spreading out lighting over more area..
...thats ppfd isn't it?
ie.150 w is intense..50w is less intense and if you have three you may cover more area
but [i do not think ]they will penetrate as far down...imho..that does not compute
 
KarmaPaymentPlan

KarmaPaymentPlan

Well-Known Member
OLD MOTHER SATIVA said:
..we are talking about penetration aren't we..not spreading out lighting over more area..
...thats ppfd isn't it?
Click to expand...
but its more light from more angles isnt that part of penetration?
how does a denser light source penetrate more? does more of it flow through the leaf because it has a higher ppfd?
 
OLD MOTHER SATIVA

OLD MOTHER SATIVA

Well-Known Member
yes i understand that..and to be fair ...nothing penetrates a leaf..it penetrates where there are openings

my post was a question..because i don't know for sure..and i am not sure you know the answer [either]
 
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