Quantum Boards or COBS?

DesertPlants said:

I was using example numbers, not exact numbers. I was demonstrating a concept, not a specific use-case. I'm not nitpicking the details. I was saying, in my opinion, LED lights appear to convert more usable energy at the higher efficiency than HPS and that not all energy goes to heat. That's all.

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Thermodynamics, in its most basic form, is really easy to wrap your head around, but in practice very hard to calculate as the situation surrounding your thermodynaic system is never perfect enough to manage all variables.
The real kicker here is that i think your probably right in a practical situation of hps-growtent vrs led-growtent: i think a 1000w hps 4x4 will run hotter than a 1000w led 4x4 and i think @nevergoodenuf tested this out, maybe he can chip in here. But i think this depends more on the how heat is transfered than what efficiency rate of HPS vrs LED. Id believe 1000W, 40% efficient led just sitting in a closed room would heat up just as much as 1000w, 60% efficient led as long as they are both on similar thermalmanagment ie passive heatsinks. The energy converted into light will always convert into heat in the end, except for a negligible amount that goes to photosynthesis. The difference between hps heat and led heat is in how the heat is transmitted, led heat is easier to get rid off.

I have run this test a few different ways and my results show much less heat watt for watt, even in a sealed tent with nothing but a wall fan inside the tent (950w in a 5'x5' on 73*f day= 84*f). I have also tested a tent with a 600 HPS with a small intake and exhaust, just enough exhaust to maintain 83*. Same tent and no change to exhaust, with my 950w fixture, the temp peaked at 78*. This is not running my COBs for efficiency, but for high intensity (4 COBs @ about 225w each). Sorry I can find the pics from my testing right now.

DesertPlants said:

It has not been removed... Photosynthesis is the reaction used for plants to turn the usable energy into something more useful to the plant. You cannot cut half a process out and just focus on one side when both of them work in tandem. Photosynthesis is endothermic. The light is not all converted to either plant fiber or heat. You are trying to say heat and photons are the same thing. They are not the same thing at all. They are both forms of energy, yes. They do both equate to the same total energy... but you can't say that one source creating 300W of heat and 700W of photons creates the same heat as one that creates 450W of hear and 550W of photons. The energy is converted to chemical energy, not just heat.

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Seriously just stop grasping at straws already.

I already said that if you were nitpicking over a few percent then I wasn't interested. Then you came back with your claim that it was 100% related to efficiency, which I explained you were wrong. And now you are back to nitpicking over a few percent again.

Besides, what led has 70% efficiency? Come on man!

If you want to nitpick then under HPS the plants evaporate more, so wouldn't that also lose heat?

In actual reality, the people who design closed grow rooms scale their airco BTU's based on the total number of watts of the lights. It doesn't matter (much) if you use led or HPS.

Did you even read my first post? The TL;DR of it was... use whatever works best for you.

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DesertPlants said:

I was using example numbers, not exact numbers. I was demonstrating a concept, not a specific use-case. I'm not nitpicking the details. I was saying, in my opinion, LED lights appear to convert more usable energy at the higher efficiency than HPS and that not all energy goes to heat. That's all.

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I get what your saying but the fact is that in the end that difference is negligible - Yes, they produce more light energy per watt, but the absorption rate by the plant is still only about 7% or so. The remaining 93% of the light created STILL ends up as heat *somewhere* inside the grow space. Yes, you make more light for the plant, but you're also making more light that ends up as heat.

DesertPlants said:

1000w going through 70% efficient LEDs will lose 30% to heat, that same 1000w through a MH or HPS bulb at 55% efficiency, will convert 45% to heat.

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if you read that vice versa you get the ~ right numbers.
led: 25-30% light
MH or HPS bulb: 20-25%
there will ! never ! be a led chip with 70% light efficiency
and today you will be lucky to find a 30% efficiency of the produced light.

as i watercool my leds - i know it`s pretty simple to ~ messure the produced heat.
have a look to this thread - to get a better idea:

https://www.rollitup.org/t/watercooled-smart-ic-cob-led-build.943904/page-5#post-13732745

greetings @wietefras --- i guess you still lack the money and/or the courage to buy condoms...

wietefras said:

the tiny fraction

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the tiny fraction of weed can be oily and greasy and > 20% THC
we know 1KG of dry firewood can reach 4-5KWh / KG

is it possible to account al the energy transformed by a plant ?

- if your calculations get very complete - this energy gets bigger and bigger.

eg. how to calculate an amount of energy, the plant needs to stay alive -
and maintaine metabolism

like bringing up quantities of water from the soil to the top during live ?
or changing O² into CO² during the night ....what power to open and close stomata ?
- and all the 1001 procedures of different chemistry that are even not entirely dismasked by science.

I use - to estimate the inverted watts:

veg / day 1-21 / 18h / 9 plants / 1sqf / 30W ----- 11,34 KWh
"--/---" 21-35 "---/----" 2 " 60W ----- 15,12 "
"---/---" 35-49 "---/----" 4 " 150W ----- 37,80 "
"---/--- " 49-63 "---/-- " 8 " 300W ----- 75,60 "
bloom/day 63-126/12h " 10 " 350W ----- 264,60 "


bloom + veg/day1-126/ 1890h ~ 214W ----- total 404,46 KWh

i harvested ~ 350g of dry buds - maybe + stems, leaves and roots are a total 1-2KG of dry material. ---> up to ~ 10KWh of stored calories.

As my led lamp is watercooled - i know, that from the back-side of my led chip i`m able to rewin
~60% of the electr. input(404,46KWh) as heat power in my heatexchanger.
~40% must be emitted as heat + light on the front-side LES.
Wrapped in the condom you see very efficient CREE XTE royal blue @ low current -
and i found ~80% of heat power inside.

LES with hot, phosphored silicone can reach temp. > 100°C @ full load -
so there must be an important amount of heat and i estimate, that it is 20% light + 20% heat.
20% of 404,46KWH = ~80KWh shared lightpower between the plant- and the room-surface.

With seedlings it`s unpossible to reach good surface coverage of the green, in relation to the rest of the grow area.
Even later when the plants stand in a closed and dense formation - it seems that they capture only a max. ~ 80% of the emitted photons - there will be always lightpower heating the soil, walls and even the roof... a bit.
Animals and we need ~ 10KG of eg. soja beans with high proteins to build up 1KG of meat.
If then plants need around ~50KWh light to build up ~5KWh of calories - i wouldn`t be surprized to see plants even more efficient in using their nutrients - than cows or we do.

Sooooo after reading 10 pages of the argument of hps vs led.........

What’s the difference between COB and Quantom Boards.....? Thanks

csovfnst said:

Sooooo after reading 10 pages of the argument of hps vs led.........

What’s the difference between COB and Quantom Boards.....? Thanks

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Light distribution. QBs provide more of an even cover over the canopy of the plants, whereas COBs will provide more intensity from a smaller area. It's just the difference between spreading the light out or having it emanate from fewer locations. Overall I think the consensus is that QBs provide better coverage for those that wish to evenly distribute light, but at a slightly higher cost. I prefer to stick with COBs for now, but at this level of efficiency, it's all about personal flavor.

this, ^ plus, quantum boards distribute heat better, so you can run them harder before you need heat sinks

DesertPlants said:

Light distribution. QBs provide more of an even cover over the canopy of the plants, whereas COBs will provide more intensity from a smaller area. It's just the difference between spreading the light out or having it emanate from fewer locations. Overall I think the consensus is that QBs provide better coverage for those that wish to evenly distribute light, but at a slightly higher cost. I prefer to stick with COBs for now, but at this level of efficiency, it's all about personal flavor.

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It is actually the opposite. A single QB provides less options for adjustable coverage than multiple cobs running at the same power. You can spread the cobs out however you see fit whereas the single board is fixed. In my opinion cobs are also better because of the larger LES.

You can get upwards of 70-80% efficiency with any LED. It is a matter of finding the current where it will only produce 20-30% heat. That might not be much light output but you can easily fix that by adding more LEDs until you reach the desired light levels.

If you are having to use heat sinks then you are wasting energy to heat generation. The traditional approach of running LEDs at high current made sense when they were expensive and it was cost effective to tack on an inexpensive heat sink. Now that LED prices have come down it makes more sense to ditch the heat sinks and drive them at currents where heat isn't an issue.

Slinging PAR said:

It is actually the opposite. A single QB provides less options for adjustable coverage than multiple cobs running at the same power. You can spread the cobs out however you see fit whereas the single board is fixed. In my opinion cobs are also better because of the larger LES.

You can get upwards of 70-80% efficiency with any LED. It is a matter of finding the current where it will only produce 20-30% heat. That might not be much light output but you can easily fix that by adding more LEDs until you reach the desired light levels.

If you are having to use heat sinks then you are wasting energy to heat generation. The traditional approach of running LEDs at high current made sense when they were expensive and it was cost effective to tack on an inexpensive heat sink. Now that LED prices have come down it makes more sense to ditch the heat sinks and drive them at currents where heat isn't an issue.

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Yep, complete opposite.

Slinging PAR said:

It is actually the opposite. A single QB provides less options for adjustable coverage than multiple cobs running at the same power. You can spread the cobs out however you see fit whereas the single board is fixed. In my opinion cobs are also better because of the larger LES.

You can get upwards of 70-80% efficiency with any LED. It is a matter of finding the current where it will only produce 20-30% heat. That might not be much light output but you can easily fix that by adding more LEDs until you reach the desired light levels.

If you are having to use heat sinks then you are wasting energy to heat generation. The traditional approach of running LEDs at high current made sense when they were expensive and it was cost effective to tack on an inexpensive heat sink. Now that LED prices have come down it makes more sense to ditch the heat sinks and drive them at currents where heat isn't an issue.

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The efficiency is not great enough to incur the cost of additional lights at the current prices. I just built four dual COB VERO 29 C lights. The COBs run at 1750mA are 119.35W a piece for a total of 238.7W per fixture.
+ Two COBs each at $28.83
+ Two Arctic Alpine 64 Plus fans at 7.99 each
+ Aluminum Angle $19
+ HLG-240H-C1750A at $58.79
+ APV-12-12 to run the fans at $7.67
+ Thermal Past x2 at $0.35
+ Screws at $2
+ Wire at $3
Total: $172.44 per light. At 1750 mA a BXRC-35G10K0-C-73-SE will emit about 16,130 lumens each, making a total of 32,260 or 187.08 lumens per dollar.

Lowering the current to 1050mA, I would need to add a third one to come close to the previous build.
Total: 169.28 per light. At 1050mA a BXRC-35G10K0-C-73-SE will emit 10,488 and that would be 31,464 lumens (slightly less, but negligible) for a total of 185.87 lumens per dollar.

It's negligible, but it is still more cost effective to run them with active cooling at a higher current. Even the cost difference in electricity doesn't work because you are driving more of them in exchange for a lower current.

Like I said, at these prices and the current efficiency, it is more about personal flavor than anything.

Of course none of this matters if you can't keep the room warm enough like me. <.< I am having to add an oil heater so they don't go purple on me again.

Oh, and I wasn't advocating QBs as better... I was saying most people on here prefer them for the even coverage. I personally only use COBs. I don't need the areas where I don't have a plant getting even coverage just like the areas where I have a plant... I prefer that light be directed where I need it.

DesertPlants said:

Of course none of this matters if you can't keep the room warm enough like me. <.< I am having to add an oil heater so they don't go purple on me again.

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Are you serious? How many watts how big of space? Quick question, do you think 2 600 watt boards and a 750 watt cob lamp will run good warm temps in an 8x12 shed? I need around 80 degrees.

a mongo frog said:

Are you serious? How many watts how big of space? Quick question, do you think 2 600 watt boards and a 750 watt cob lamp will run good warm temps in an 8x12 shed? I need around 80 degrees.

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Depends on the ambient temperature and humidity. I am sitting at 40% humidity, but it's in my basement, which doesn't have active air handling from the furnace, so I have to supplement the heat. Best you can do is try it out and see how it goes. If you have the details about the humidity and ambient temp, someone on here will likely have an idea if it will work.

The tent I have them in right now is just a little 2.5' x 5' and I only have two of them running as I am doing the party cup competition and don't have a full grow going. I am sitting at about 477w for 12 sq ft, which is in the 35-50 range per sq ft you want. At 8' x 12' you would want about 2880 watts to light the whole thing with at least 30 watts per sq ft, but that's only if it is packed and the actual numbers will depend on efficiency, temp, and humidity.

DesertPlants said:

At 8' x 12' you would want about 2880 watts

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Im replacing 3000 watts of hps in that shed. Not sure if your taking into account working room in your 2880 watts.

a mongo frog said:

Im replacing 3000 watts of hps in that shed. Not sure if your taking into account working room in your 2880 watts.

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No, that was for packing the whole thing. What you have should be perfect for 8x8

DesertPlants said:

No, that was for packing the whole thing. What you have should be perfect for 8x8

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Ok. Thanks.

DesertPlants said:

Lowering the current to 1050mA, I would need to add a third one to come close to the previous build.

+ Three COBs each at $28.83
+ No fans
+ Aluminum Angle $19
+ HLG-240H-C1050A at $58.79
+ No fan driver
+ No thermal paste
+ Screws at $2
+ Wire at $3​

Total: 169.28 per light. At 1050mA a BXRC-35G10K0-C-73-SE will emit 10,488 and that would be 31,464 lumens (slightly less, but negligible) for a total of 185.87 lumens per dollar

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No way in hell you can run those at that current with no heatsink.

nfhiggs said:

No way in hell you can run those at that current with no heatsink.

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Are you talking about at 1050mA? The lowest the run at is 855mA. At 1050mA, you may be able to do with just basic heat transfer to the aluminum frame. I wouldn't recommend it and you will likely shorten the life... I was just using it as an example for numbers comparison.