Are LEDs Misunderstood?

SupraSPL · Nov 3, 2010

aha I can see how that could use some explaining. We calculate the surface area of the heatsink and based on that it will cool a certain amount of dissipation watts. I think KNNA is recommending 110cm2 per watt now and that number will fall as the LEDs get more efficient. If you add a fan the number drops further.

So if a heatsink has very tall fins it will have more watts attached to it but covering the same space, increasing the light density. It would not be difficult to increase the light density too far because photosynthetic efficiency decreases at higher photon densities. It is better to spread that light as evenly as possible and to stay within the recommended light density range (I think KNNA recommends 250-300 dissipation watts per sq meter but that may have decreased because we have better white bins and better red spectrum now.)

For vegging you can use a much lower light density and still get HID like growth or better, so in those cases it is helpful to use heatsinks that have shorter fins or lower surface areas.

Weezard · Nov 3, 2010

OK, thanks. :whee:

But, I want some of what you're smokin'.

Aloha,
Weeze

PetFlora · Nov 10, 2010

Being a personal use grower with a UFO 90 from Sunshine Systems, what supplemental lighting should I use for veg or bloom? It does veg well, with thick main stem, broad leaves, and close inter-nodes.

I am thinking a 150-250 CMH used vertically, but isn't the damn ballast expensive? And then there's the extra heat that might need venting, which adds more expense.

Also considering a Spectra 180, formally Grow Hydro LED- (Cammie ripped off his name). It's a 3 watt multi-spectrum, but $500

Then I looked at the Quantum T 5 Bad Boy (8 bulb easily finish 3-4 low Ryder type), And I can buy with all 2900 bulbs for bloom. $231 + $96 for an 8 pack of bulbs. SIGH! My hydro dealer says they have QC issues, but when they work they are great. The bulbs are easy to replace/change, plus you can play sun by mixing 6500s with 2900s in late veg, early bloom, and finish. Seems like that would be beneficial. What do you guys think? http://growgreenmi.com/quantum-lamp-fixture-p-5866.html

Hell, that might take the place of my UFO, or I veg under UFO and finish under Bad Boy. Hmmmmmmm :artist:

Anybody?

MrSterling · Nov 12, 2010

yesum · Nov 12, 2010

PetFlora said:
Being a personal use grower with a UFO 90 from Sunshine Systems, what supplemental lighting should I use for veg or bloom? It does veg well, with thick main stem, broad leaves, and close inter-nodes.

I am thinking a 150-250 CMH used vertically, but isn't the damn ballast expensive? And then there's the extra heat that might need venting, which adds more expense.

Also considering a Spectra 180, formally Grow Hydro LED- (Cammie ripped off his name). It's a 3 watt multi-spectrum, but $500

Then I looked at the Quantum T 5 Bad Boy (8 bulb easily finish 3-4 low Ryder type), And I can buy with all 2900 bulbs for bloom. $231 + $96 for an 8 pack of bulbs. SIGH! My hydro dealer says they have QC issues, but when they work they are great. The bulbs are easy to replace/change, plus you can play sun by mixing 6500s with 2900s in late veg, early bloom, and finish. Seems like that would be beneficial. What do you guys think? http://growgreenmi.com/quantum-lamp-fixture-p-5866.html

Hell, that might take the place of my UFO, or I veg under UFO and finish under Bad Boy. Hmmmmmmm

Anybody?

I have LED overhead and supplemented with 1 55 watt pll hanging vertically in middle of 5 plants for flower. Reason is the lower buds do not get enough light from overhead. You can also put the pll's in corner of tent with reflectors. Got mine at ahsupply.com, but you can make your own cheaper, 1000bulbs.com for cheap lights.

The flouros have a wide even spectrum, the k value is just a spike, do not worry about values. I vegged under 2700k cfl's and the internodes were very tight. I would veg and flower under 3000k to save switching.

Weezard · Nov 12, 2010

Gentlemen, start yer stirling engines

Gentlemen, start yer stirling engines

MrSterling said:
Hey guys, sorry if this post is misplaced, but this seems to be the only central discussion of LED in the subforum. Is there a central source for info on LED effectiveness, heat, energy used, etc? I'm interested in using LED, but I've been having a really hard finding reputable information.

Aloha, Mr. Sterling :tiphat:

I do not sell lights.
Don't even :pimp3:

other people's lights.

But I have been futzing around with LEDs for 35 years or so, although, I'm no pro.

Recently had some luck with homebrew grow lamps.
(Click on my avatar and browse the albums.)

So, I am able offer first hand knowledge and experience.
Shoot me a visitor's message.

Specifically, how can I help you?

ciao
Weezard.

FreezerBoy · Nov 14, 2010

MrSterling said:
Hey guys, sorry if this post is misplaced, but this seems to be the only central discussion of LED in the subforum. Is there a central source for info on LED effectiveness, heat, energy used, etc? I'm interested in using LED, but I've been having a really hard finding reputable information.

Don't know if this is the type of info you seek but, here are some links to grows using LEDs:

Sleepy, Hazy, Verdant Green, Blazeoneup

Shafto · Nov 15, 2010

I only read through the first couple pages, but secondtry is bang on with his understanding of lighting and LEDs.

I work with LEDs every day, doing some pretty interesting things, I understand them intimately. While I do love them, I understand their limits, and I hate to see them misrepresented. They have unbelieveable advantages in so many applications, it's so unfortunate to see them bastardized by people trying to make a quick buck.

Over 90% of the LED products I investigate have extremely inadequate thermal consideration. Popular to contrary belief, LEDs do make heat, and quite a bit of it. Similar levels of electricity to heat/light conversion as HPS HID lighting. The difference is that LEDs conduct heat away from the junction(out the rear), whereas HIDs mostly emit the heat as radiation.

They do work, but not as well as HIDs. When manufacturers of LEDs (no, none of those grow lamps actually use their own LEDs) actually start building blue dies that have phosphor wavelength conversion directed at photosynthesis will we have good LED grow lights. (like the pink flruoros but much better)

For now the market for this is far too small to merit the production of LEDs this specifi, and this is why all manufacturers use generic LEDs, most often cheap no-name LEDs from China with no datasheet.

If you can't request the manufacturer LED datasheet, and receieve it from the vendor, then the product is most definitely total crap.

If the LEDs aren't CREE, OSRAM, Lumileds, SSC, Nichia, Luminus, Bridgelux, or a few other noteables, then they are most likely crap.

Even if they are of good quality, if they do not have an efficienct thermal path to dissipate heat, efficiency will go way, way down as the LEDs heat up, and you can say good-bye to that long lifespan you expected.

I've done many tests of commercial LED products falling to 50%, 40% and even under 30% output after only 1000 hours of use in 25C ambient temp. All claiming 50,000 to 100,000 hours.

The LED manufacturers datasheet will state what junction temperature those claims are accurate with. Most often with low quality LEDs this rating will be at 25C, while high quality LEDs will be rated at 60-100C as well.

LEDs are misunderstood, very much so, and this understanding is very much taken advantage of.

BigBlack81 · Nov 15, 2010

Shafto said:
I only read through the first couple pages, but secondtry is bang on with his understanding of lighting and LEDs.

I work with LEDs every day, doing some pretty interesting things, I understand them intimately. While I do love them, I understand their limits, and I hate to see them misrepresented. They have unbelieveable advantages in so many applications, it's so unfortunate to see them bastardized by people trying to make a quick buck.

Over 90% of the LED products I investigate have extremely inadequate thermal consideration. Popular to contrary belief, LEDs do make heat, and quite a bit of it. Similar levels of electricity to heat/light conversion as HPS HID lighting. The difference is that LEDs conduct heat away from the junction(out the rear), whereas HIDs mostly emit the heat as radiation.

They do work, but not as well as HIDs. When manufacturers of LEDs (no, none of those grow lamps actually use their own LEDs) actually start building blue dies that have phosphor wavelength conversion directed at photosynthesis will we have good LED grow lights. (like the pink flruoros but much better)

For now the market for this is far too small to merit the production of LEDs this specifi, and this is why all manufacturers use generic LEDs, most often cheap no-name LEDs from China with no datasheet.

If you can't request the manufacturer LED datasheet, and receieve it from the vendor, then the product is most definitely total crap.

If the LEDs aren't CREE, OSRAM, Lumileds, SSC, Nichia, Luminus, Bridgelux, or a few other noteables, then they are most likely crap.

Even if they are of good quality, if they do not have an efficienct thermal path to dissipate heat, efficiency will go way, way down as the LEDs heat up, and you can say good-bye to that long lifespan you expected.

I've done many tests of commercial LED products falling to 50%, 40% and even under 30% output after only 1000 hours of use in 25C ambient temp. All claiming 50,000 to 100,000 hours.

The LED manufacturers datasheet will state what junction temperature those claims are accurate with. Most often with low quality LEDs this rating will be at 25C, while high quality LEDs will be rated at 60-100C as well.

LEDs are misunderstood, very much so, and this understanding is very much taken advantage of.

So IYO, are there currently any brands of LED lights that do exceed the issues you've written about here?

And BTW, to all those who hate on LED's I'm personally thinking for an NGB styled setup for micro and mini/midi size growers, the issues with HID's make LED's a much more attractive option, especially when trying to keep the stealth and safety issues of a grow in check. To me, distance to the light source is key and since we've seen time and time again that they key in micro grows is light distance and training, it would seem to me that micro grows, LED's have the potential to do good things.

For all those who are blessed with the resources and the means to do a larger grow with HID's, go for it. But as for me and my limited resources, I need to check these LED's out and see what the deal is. Less heat and less issues setting up a ventilation/masking system in a small box make LED's very attractive to me.

Shafto · Nov 15, 2010

There isn't less heat, there is less emitted heat. You still need the same ventilation to remove the heat from the LED junctions. Unless you use less overall wattage than you would HID, then your ventilation could be less.

If the advantages of having the LEDs closer, and the ability to place individual smaller light sources for training and such, excede the advantages of an HID light source, then so be it, they have another advantaged application.

I would be careful about putting them too close though. Any blue light not absorbed by the plant will turn into a lot of heat on the leaf surface. Photometric power not absorded will convert into heat and burn, just like a wide beam laser.

Holding high output LEDs directly over a piece of wood will actually burn the wood. No heat is emitted, it's all the photometric power converting to heat as it hits the surface.

Yes you can place them closer, and they do emit no heat, but you really do still have to understand what you're doing. This doesn't mean there will be no heat.

BigBlack81 · Nov 15, 2010

Shafto, thanks for the reply and thanks for the good words. These are things all LED growers should know about.

For the record, I still would want to keep a good distance from the lights so the tip burn is non-existent but in the space I want to grow in, the main issue will be ventilation so having 120W of LED that could do the work of 150W of HPS with less emitted heat WILL make my fabrication and design easier.

I was just asserting that for box grows, LED's provide advantages because of the style of growing that most box/micro growers have to grow in. If you have space, use the method most appropriate to the space you're growing in was all I was trying to say. Hell, if I could grow SOG clones under big 600W lamps in a sealed room, I'd be a happy camper. But given the confines of the flowering chambers in most small boxes closer lights work better.

I didn't know, however, that photometric power not absorbed will convert into heat. That puts the entire arguement about LED's vs HID in a new context for me in terms of both the light I want to use AND the box I want to build. This is something that we ALL have to think about and kudos to you for pointing that out.

With all that, what LED's have you seen given all this could work for my needs? My flowering chamber is 2'x2'x3' (LxWxH).

Shafto · Nov 15, 2010

Some of the photometric power not converted will reflect, but much will turn into heat, especially blue wavelengths.

Plants don't appear green necissarily because they are green, but because they absorb blue and red wavelengths, and reflect back most green. An interesting way to think about it anyway.

As for commercial LED grow lights, I haven't investigated any, but the same engineering approach is applied to any LED array.

I'm not saying that they're all crap either, some may be built very well. Just a word of caution, as most aren't in the general LED world. Ask for the name brand of, and manufacturer datasheet for the LEDs being used in the array. Ask about thermal resistance from junction to ambient. If the commercial supplier cannot readily provide such information, the product is crap.

Taking an LED that says 100,000 hours in the datasheet at 25C and letting it run with a 100C/W to ambient resistance and claiming that it will last 100,000 hours is just like saying your engine oil will last 3000 miles whether you're driving around town or redlining it around 3000 mile endurance race track.

One of the real advantages to LEDs in growing, unutilized to my knowledge so far, would be the ability to passively conduct the heat created out of the room.

Since LEDs create heat at the junction, that needs to be conducted out of the rear, solid heat conductors, or preferably heatpipes could be used to conduct heat out and on top of a small cabnet, taking it completely out of the growing area with no ventilation needed.

Weezard · Nov 15, 2010

I've cooked a bud or two with radiometric energy.

I've cooked a bud or two with radiometric energy.

Howzit, Shafto?

"Since LEDs create heat at the junction, that needs to be conducted out of the rear, solid heat conductors, or preferably heatpipes could be used to conduct heat out and on top of a small cabnet, taking it completely out of the growing area with no ventilation needed."

Kinda like dis, yah?

Works a treat!
Nominal 180W. Actual ~155W.
Uses a special run of 15W. 660nm. Ledengin emitters.

The commercial efforts are getting better, but Underwrighter's Laboratories would flunk most of them.
I do agree with most of your points.

'cept the HID vs LED quality issue.
Because my experience has shown otherwise.

Aloha,
Weezard

PetFlora · Nov 15, 2010

Wow I am very glad I started this thread. Hopefully it continues to keep subscribers current on new developments to make LEDs commercially viable, and less expensive.

There's a new boy i town Apache something. They have engineered their LED so at least power supplies are easily changed with a screw driver, and supposedly more efficient, but 120 watt is $999.00. Intro scheduled for January 2011.

Instead of getting another LED to compliment my UFO 90, I ordered a Quantum T- 5 Bad Boy- 8 bulb, with 8 each 2900 and 6500 bulbs. Total less than $350 including shipping. The fixture is 2 X 4. Each bulb is 50K lumens totaling ~400watts. There is a video of temp taken 4" under the fixture ~ 80 degrees.

I plan to perpetual grow using my UFO 90 to veg/clone and finish under the Bad Boy. google it to find a link to a grow journal on another emag.

I plan on slowly introducing the 2900 bulbs to simulate autumn to fall light variations. Oh, bulbs are only $5.00

shovit · Nov 16, 2010

I wonder when someone will release a watercooled LED lights. I can't see really how it would differ from existing cooling for computers.

Water comes in from outside the growarea passes thru the cooler and back into the radiator. If you could place the radiator in a cool spot the LEDs will run much cooler than the growarea itself and even prolonge the LEDs life?

This would remove the heat efficiently and take up much less space than bulky ventilation. This would be awesome for small grows or tents where you don't have much space for anything really.

SupraSPL · Nov 16, 2010

Hi shovit that is an interesting idea. My first thought is that watercooling could allow for a much greater density of light in the growroom. As LEDs become more and more efficient at converting electricity into light there is less and less waste heat. We are already using LEDs that are efficient enough for passive heatsink cooling and light density can easily surpass the "sweet spot" (about 250 dissipation watts per sq meter with current bins). When light density passes that sweet spot photosynthetic efficiency decreases (although overall yield will increase up to a certain point).

So if space is your main limitation go ahead and pack the light density in, maybe even using water cooling. But if electricity is your main limitation select a larger grow space and spread the light at a lower density.

SupraSPL · Nov 16, 2010

Shafto said:
There isn't less heat, there is less emitted heat. You still need the same ventilation to remove the heat from the LED junctions. Unless you use less overall wattage than you would HID, then your ventilation could be less.

This is a good point I am always reminding myself. The radiometric efficiency of practical LEDs is slightly lower than the very best HIDs, so there would be an equal amount of heat. But in practice we are using less overall wattage due to a more efficient spectrum and the lack of reflector and glass shield, so there is less heat to exhaust (about half as much with a top notch LED lamp)

darko_G · Nov 16, 2010

always amazes me the knowledgable brains you can find on ic mag... bvunch of stoners clearly fuckin scientists (even if only in their own right)

sorry jus wanted to say that. i have nothing of any interest to mention on l.e.d's other than when the prices come down ill buy one... not enough dough atm

knna · Nov 16, 2010

Shafto said:
Some of the photometric power not converted will reflect, but much will turn into heat, especially blue wavelengths.

Plants don't appear green necissarily because they are green, but because they absorb blue and red wavelengths, and reflect back most green. An interesting way to think about it anyway.

As for commercial LED grow lights, I haven't investigated any, but the same engineering approach is applied to any LED array.

I'm not saying that they're all crap either, some may be built very well. Just a word of caution, as most aren't in the general LED world. Ask for the name brand of, and manufacturer datasheet for the LEDs being used in the array. Ask about thermal resistance from junction to ambient. If the commercial supplier cannot readily provide such information, the product is crap.

Taking an LED that says 100,000 hours in the datasheet at 25C and letting it run with a 100C/W to ambient resistance and claiming that it will last 100,000 hours is just like saying your engine oil will last 3000 miles whether you're driving around town or redlining it around 3000 mile endurance race track.

One of the real advantages to LEDs in growing, unutilized to my knowledge so far, would be the ability to passively conduct the heat created out of the room.

Since LEDs create heat at the junction, that needs to be conducted out of the rear, solid heat conductors, or preferably heatpipes could be used to conduct heat out and on top of a small cabnet, taking it completely out of the growing area with no ventilation needed.

Very well explained. The main problem of LEDs right now is the full market is very inmature. Consumers dont know what to ask, many manufacturers have a very low expertise level. Result is lots of crappy LED products.

Two weeks ago I was on a fair, and distributor of a LED brand was encouraging me to desing the lamp to work with chip temperatures over 120ºC and up to the limit of 150ºC. I know perfectly how the lm depreciation exponentially increases since junction temperature goes over 80-90ºC, but he insisted that doing so is reliable. Doing it allows to save alot on components and reduce heatsink, but its clearly a way to have an unuseful lamp in way less than 10Kh. At 150ºC, probably in less than 1000h. If distributors says such things, its impossible to have reliable lamps on the market. More yet, people doing good designed lamps cant compete because cost is higher and all people ends doing crap; at the end, most consumers wont notice the difference

PetFlora · Nov 17, 2010

I had a brain fart. you guys will let me know if it smells. :pie:

I don't recall their name but there is a company that makes a rotating light system with 4 to 6 arms. At the end of each arm is a different spectral bulb. I think it was a tiny HID, but not led. You could configure the bulbs any way you want

Question:

Would say something like 5 watt LEDs of different spectrums, slowly moving over the canopy be worth doing?

Meanwhile I assembled my Quantum T 5 Bad Boy today. Can't wait to employ it. Seeds are cracked and getting oxygenated in my new DIY mini bubble starter/cloner, using a 6 liter storage container and one 10" bubble stone. It can holdup to 4 @ 10"stones. I may add a second stone for fun :artist:

trying to locate the website of the rotating fixture I came across this Thinking outside the box http://www.spectrumlighting.com.au/led_tube_lights.php

This is close to what I am referring to http://www.utopiasupply.com/index.p...ategory_id=33&option=com_virtuemart&Itemid=53

Are LEDs Misunderstood?

Member

Attachments

Hawaiian Inebriatti

Well-known member

MrSterling

Well-known member

Hawaiian Inebriatti

Was blind but now IC Puckbunny in Training

Member

Member

Member

Member

Member

Hawaiian Inebriatti

Well-known member

New member

Member

Member

Member

Member

Well-known member