# LED Grow Lights



## z_adam.francis (Nov 19, 2010)

Hey Everyone, 



Newbie in the house.. I recently discovered Aquaponics and started putting together a system.. for my grow lights I wanted to use LED's.. 



I've been a residential electrician for a while now so I'm willing to build my own lights if it means I can make them bigger and stronger for a cheaper price.. 



I would really appreciate ANY info you guys and gals can give me to direct me to the promise land!



thanks!



Adam


----------



## Aepoc (Oct 21, 2011)

I'm looking for some info too... I know you need red, orange, blue and possibly some white LEDs to get the right spectrum... I'm sorry I can't tell you much more than that... Use a lot of LEds


----------



## jason 77 (Oct 21, 2011)

You do realize that the OP posted this almost a full year ago and apparently hasn't posted anything since?


----------



## dr.d (Oct 21, 2011)

It's not that simple. Different wavelengths are required at different growth phases. UV in the vegetative phase, then more red-shifted during the flowering phase, etc.. I have used regular Sylvania grow lamps on the front porch for a Rosemary bush that didn't get enough sunlight and it seemed to help, but I've never attempted to grow anything indoors.


----------



## stephenTheObdurate (Oct 23, 2011)

There's lots of arm waving about frequencies with little hard facts and there is quite a bit of unconnected knowledge. There are two types of chlorophyll and each absorb light in two different fairly narrow frequency bands that are slightly shifted from each other. I have found no information whether they just absorb these frequencies or they really need both, or whether these are complementary chemicals to use more of the available light. Perhaps you only need to activate either one for proper plant growth.

The proportion of different frequencies in sunlight differs with the season and direct sun v.s. shade so some ratios are better for growth and some promote flowering. I have seen completely opposite suggestions and experimental results for different ratios. Much of the scientific research is based on chemical absorbtion, which may or may not be directly related to conversion.

Many of the commercial lights for sale use wide angle LEDs which can be placed close to the plants if you only want to stimulate the leaves at the top of the plant. At double the distance you get 1/4th the intensity. A wide angle designed to be placed a foot from the top will only supply a 1/16th as much light to bottom leaves on a 2 foot tall plant.

No LEDs exactly match the chlorophyll absorbtion band but some are close. It's also not clear if close is good enough.

Leaves are green because they don't absorb green light. If the grow light output were perfect the plants would appear black. Sodium vapor lamps put out lots of light and are quite efficient overall but most of their output is wasted. I have not seen any comparison of different lights that compares usable light.

This is just off the top of my head. I have more specific information I gathered for an aborted grow light project, including samples of research, spec evaluation of some off shore LEDs and prices, and so on if anyone is interested. I would have to find it and it's about a year old. It's quite a few pages. If anyone's interested how would I post it?

- Stephen


----------



## [email protected] (Oct 24, 2011)

Hey everyone.. nice forums!! I have a question about grow lights... I'm trying to build my own light with 4 5600k Bridgelux RS Arrays BXRA-C8000-00E0C. They're rated at 8000 lumens each, so that would give me about 32000 lumens... about the same as a 400W MH light. Thing is i'm not sure if i should go with that or if i should get 32 Cree XLamp XM-L XMLAWT-00-0000-0000T6051, rated at 1000 lumens each and link them all together... what do you guys think?


----------



## stephenTheObdurate (Oct 24, 2011)

These are both wide angle lights that will do well to light very wide flat plants but they put out a lot of wasted lights to the side and drop off extremely quickly for lower leaves without reflectors and such. They have about the ranges normally accepted as good for growth, though they also have a bit of wasted frequencies, reducing their effictiveness. They also don't have any way to vary the ratio of the peaks. The red/blue ratio is different for growth than for flowering. It might be best to buy separate red and blue LEDs so you can alter the ratio as the plants grow and mature.

- Stephen





400-520nm This range includes violet, blue, and green bands. Peak absorption by chlorophyll occurs, and a strong influence on photosynthesis (promotes vegetative growth.)
520-610nm This range includes the green, yellow, and orange bands and has less absorption by pigments.
610-720nm This is the red band. Large amounts of absorption by chlorophyll occur, and most significant influence on photosynthesis (promotes budding and flowering.)


----------



## [email protected] (Oct 24, 2011)

I know that plants need certain frequencies of light to grow mostly red & blue. But i don't really want to mess with mixing all the different nm LED's, plus i don't like the look of the red/blue on the plants. So i decided to go with the 5600k/daylight full spectrum. But like you said it lacks a bit in the orange/red part of the spectrum.. So.. what if i put 2 3000k Bridgelux RS Arrays (BXRA-W5700-00Q0E), together with 2 5600k Bridgelux RS Arrays? This way it'll fix the part of the spectrum that's lacking?? Also do you think 4 of these might help fix the 120 degree angle??http://www.arccoinc.com/led.html Besides a MH bulb for example has a 360 degree angle, that's what the reflector is for.


----------



## jcf1 (Dec 11, 2011)

stephenTheObdurate said:


> There's lots of arm waving about frequencies with little hard facts and there is quite a bit of unconnected knowledge. There are two types of chlorophyll and each absorb light in two different fairly narrow frequency bands that are slightly shifted from each other. I have found no information whether they just absorb these frequencies or they really need both, or whether these are complementary chemicals to use more of the available light. Perhaps you only need to activate either one for proper plant growth.
> 
> The proportion of different frequencies in sunlight differs with the season and direct sun v.s. shade so some ratios are better for growth and some promote flowering. I have seen completely opposite suggestions and experimental results for different ratios. Much of the scientific research is based on chemical absorbtion, which may or may not be directly related to conversion.
> 
> ...




Not quite right - the 'bands' you refer to for the chlorophyll are just absorption peaks for the 2 types of 'theoretical photosystems' which are just clusters of many of these pigments (accessory pigments and a primary - the cholorphyll typically). The actual absorption spectrum of either chlorophyll will not correspond to the action spectrum for the plant anyway. Simply put (as you hinted at) - absorption does not equal photosynthesis exactly, and also chlorophyll absorption OR action is not even part of the story when it comes to calculating growth. For proper growth you theortically need to excite both theoretical photosystems, but this can be done directly or with corresponding accessory pigments which absorb at many wavelengths. The text book values you see for these (P680, P720 or similar) are just that. 

You'd want to know the action spectrum of EVERY pigment in that plant, superimpose it and then create an array of lights to suit. Even after doing so this you don't know the intesities of each, or which is most effective and it doesn't cover control of growth from the photosensitive hormones. The red shifted light vs blue shifted for flowering/vegetative growth is caused by something else entirely and not directly related to photosynthesis, although it influences its rate and the fate of its products.

Basically what I am saying is that pratting around with wavelengths beyond a certain extent is really a bit fruitless. LEDs are always going to underperform - just look at even the most diverse array with a diffraction grating vs a sodium lamp and you'll see what I mean. There are so many holes in the spectrum that you really will be missing some photoexcitation of pigments somehwere or not converting some hormone or another. Best bet is to try and get as close to spring/summer sun (like a metal halide) and then summer/autumn (like a sodium). Of course I am assuming that you are growing some kind of short day flowering herb here 

Sorry - Biology is kinda my job, just can't help myself...


----------



## Kestrel (Dec 14, 2011)

jason 77 said:


> You do realize that the OP posted this almost a full year ago and apparently hasn't posted anything since?


Actually, this is a 'z_' thread (i.e. the OP's username) - after the thread was originally posted, any subsequent replies were lost in the crash earlier this year. Post #1's were recovered but not the replies. The OP may have even reregistered since then. :shrug:


----------



## joewatts (Jan 24, 2012)

You can now buy mix a source LED chips which is a red, green and blue led in 1 chip. These would be ideal because you can easily and precisely change the output colour using a controller.


----------



## cam453 (Jan 25, 2012)

Anyone have any good boost driver set ups for multiple high powered leds?


----------



## hotdrop (Jan 26, 2012)

Your biggest problem would be cost here. Lumes per watt you aren't doing much better then HPS or CFL with LEDS and it costs a lot of money to get even 100 watts worth of LEDs. For comparison HPS at 400 watt is right around 100 lumens per watt, a top of the line CREE LED might run closer to 200 in the white spectrum and less in the reds and blues. but cost 4-5$ a piece. A 100 led setup would eisily run you somewhere around $600+ with driver and heatsink.


----------



## johnawares (Feb 6, 2012)

Led Grow Lights said:


> Not all plants require the same color of light to grow, and they may need different colors of light at varying stages of development. LED grow lights are available in several colors. Your seedlings can have the blue light they usually need, fruit bearing plants can enjoy orange light, and your flowering plants can obtain their optimal development with red light. LED grow lights are better for the environment, your personal energy budget, and your indoor plants.



I agree with you. It depends on the type of plants you want to grow. The size, light beam angle, and lumens of led grow lights are not very important. The most important thing to consider is the wavelength of the lights. For growing plants its good to use a combination of red and blue lights. Red lights should have a frequency of around 625 nanometers and blue should be around 465nm.

Sales Links Removed - Norm


----------



## pretmetled (Feb 6, 2012)

hotdrop said:


> Your biggest problem would be cost here. Lumes per watt you aren't doing much better then HPS or CFL with LEDS and it costs a lot of money to get even 100 watts worth of LEDs..



Stupid question regarding Lumens / Watt / $$$. Please bear in mind I'm new to this whole led business. 

I see that the main discussion on this forum with regard to high output is always centered around power LEDs, as in 1 Watt and beyond. Probably with good reason, but I wonder why.

Are these 1+ Watt emitters (CREE etc) the best bang for your buck? As in best lumens / watt / $. Or it it just that a single emitter (lets say 1 Watt) is far more convenient to work with than say 10 low powered emitters (100 mW each) on the same PCB, lets say in a series arrangement. I would _guess_ that when area is not at a premium (so no flashlights, but say fixed lighting), then using a lot of smaller emitters has some advantages as well. But as said I'm new to this, so I may very well be missing the obvious...


----------



## Freeze_XJ (Feb 6, 2012)

Well yes, we mostly focus on power leds, because space is limited in a flashlight  If you can use all space you want, using powerLEDs (which have a somewhat more efficient technique of bringing out the light, with multiple junctions instead of just 1 in the 'normal' 3/5mm leds) is still the way to go, but you shouldn't drive them as hard. There are enough of these around, and the cost premium isn't that big. Actually, I'd say that per lumen the powerleds are cheaper after all, and when factoring in the efficiency, they are definately cheaper. Besides, you would have to control all minileds carefully, and that requires some kind of tuning/logic circuit.


----------



## pretmetled (Feb 6, 2012)

Thanks for your reply! Actually I think the power leds with multiple junctions you describe may just be what I am looking for. That is, if those are in a series arrangement with a higher forward voltage. You mention there's enough of those around ... Could you make a suggestion for white / red / green / blue candidates? Or maybe just the whites, and hopefully I will be able to find the rest within the same led family.

Ideally I'm looking for something of moderate power, and with a large-ish (lets say 15 Volt) forward voltage. I did look for that, but came up empty. *blind*


----------



## blasterman (Feb 6, 2012)

The reason that 1watt and lower LEDs are commonly used in growth lights is that most of those lights are Ebay class junk, and the Chinese haven't quite figured how to make power emitters over 1watt with competitive consistency. Typically their 3watt variants have half the performance of top end Cree's and Rebels and yet cost half the price. By simple math and power savings I'd rather have the Crees and Rebels.

Recently I tore out all the royals I was using in my plant lights and switched to cool white XP-Gs. While a little less efficient this way the aethestic improvement was substantial. Combined with triple up Cree Reds it actually looks fairly nice -vs- the glowing monochrome purple of the old rig. It's too soon to see how it affects plant growth vs royal blue + 630nm red.


----------



## RamblinWreck (Feb 7, 2012)

Keep us posted as I'm very interested to hear your results with the cool whites.


----------



## Freeze_XJ (Feb 9, 2012)

pretmetled said:


> Thanks for your reply! Actually I think the power leds with multiple junctions you describe may just be what I am looking for. That is, if those are in a series arrangement with a higher forward voltage. You mention there's enough of those around ... Could you make a suggestion for white / red / green / blue candidates? Or maybe just the whites, and hopefully I will be able to find the rest within the same led family.
> 
> Ideally I'm looking for something of moderate power, and with a large-ish (lets say 15 Volt) forward voltage. I did look for that, but came up empty. *blind*


Well they're not exactly parallel, but for simplicity you can consider them as such... Most LEDs operate around 3 V, and anything else has to be converted for them. That's due to material properties of the stuff the actual junction was made of (InGaN usually). Your best bet is to find either a decent white led with roughly the peaks you're looking for, or to go shopping at a LED supplier (i'm not giving links here because they'll get removed, but roughly any reputable dealer is OK) and combine some of his colors on a circuit board of your own making. I'm afraid there are few clear-cut solutions, for the reason Blasterman mentioned (the market is flooded with Chinese rubbish, and the solid olde manufacturers prefer the common fluorescent tubes). 
Probably XP-G or so will be your best bet, they are made in various colours (see the Cree website, look for XLamp XP-G or XM-L and the Binning & Labelling datasheet, that gives you an overview).


----------



## pretmetled (Feb 10, 2012)

Freeze_XJ said:


> Well they're not exactly parallel, but for simplicity you can consider them as such... Most LEDs operate around 3 V, and anything else has to be converted for them. That's due to material properties of the stuff the actual junction was made of (InGaN usually). Your best bet is to find either a decent white led with roughly the peaks you're looking for, or to go shopping at a LED supplier (i'm not giving links here because they'll get removed, but roughly any reputable dealer is OK) and combine some of his colors on a circuit board of your own making. I'm afraid there are few clear-cut solutions, for the reason Blasterman mentioned (the market is flooded with Chinese rubbish, and the solid olde manufacturers prefer the common fluorescent tubes).
> Probably XP-G or so will be your best bet, they are made in various colours (see the Cree website, look for XLamp XP-G or XM-L and the Binning & Labelling datasheet, that gives you an overview).




Parallel? Do you mean series, because I was looking for series? ;-) Purely for the higher forward voltage, such that making a reasonably efficient driver is not super hard. But I'm slowly coming to the conclusion that it is as you say. There are no clear-cut solutions. There are some vendors that do supply the series arrangement as so called "high voltage leds". But those are too expensive and/or the wrong voltage. And usually both.  Looks like combining it on the PCB is indeed the way to go. Currently it looks like about 16-18 leds (200 mW each) on a 10x10 cm FR4 board, 0.8 mm thick, plenty of open via's, HASL surface finish, and keep fingers crossed hoping the leds don't get too warm. And the 16-18 number a bit depending on the choice of red leds and choice of driver.

Thanks for the XP-G tip, will check those out. Possibly that will be "check it out _again_". Have been looking at so many led datasheets the past few days, hard to keep all the names straight. 

PS: Regarding LED suppliers, please feel free to send a PM about that.


----------



## blasterman (Feb 10, 2012)

Pretmetled, if you could give us more details into what you are trying to make perhaps we could help. Plant lights are really no different than reef lights we make, often into the several hundred watt range. I have a five foot aluminum plant rail at home running three triple-up 625nm Crees and seven cool-white XP-Gs all driven in series off a $16 Mean Well AC driver. Can't get any simplier/cheaper/efficient than that. I can't use more because that's as much heat as can be passively removed.

Running cool-whites rather than royals produces that same effect as royals that I can tell. Leaves of houseplants grow thick and dense within a few days and start to feel like vinyl. Plus, the cool-blues I got from RapidLED were a very warm bin, so they look really good. My problem is I'm cold blooded and during the winter I keep my living spaces about 60F, so things grow slow.


----------



## pretmetled (Feb 11, 2012)

The real short version is: I am looking for emitters in the 100 - 200 mW range for white, red, green, blue and RGB. So for the RGB's I'm looking at either 3 seperate leds, or 1 package with 3 dies. Basically whatever option gives better price/performance.

I'd like to make a bunch of RGBW lamps for general room lighting. So essentially a fairly large number of lamps where I can set the color + intensity. I went over a bunch of options and all in all 120 degrees leds seem to be a good choice. I want to keep cooling as simple as possible. Since area is NOT at a premium a PCB with an array of mid-power (100 - 200 mW) leds seems to be the ticket.

For a 10 x 10 cm board with 16 leds on it that gives a power dissipation of 1.6 - 3.2 Watt, depending on led specifics. So far it seems that RGB leds are more expensive than seperate R/G/B leds for the same amount of output, but I'm toying with both options.

So a 16 led layout could be either:

RGRG
BWBW
RGRG
BWBW

or

CWCW
WCWC
CWCW
WCWC

where C is an RGB (Color) led.

Nothing is written in stone here, I just use the 16 led layout example because it's easy for discussion.

Each channel R,G,B,W has to be dimmable. If you happen to know a cheap dimming option that is still cheap when multiplied by 64 channels then I'd love to hear about it.  So far a circuit based on the TLC5943 is the best I could come up with price/performance wise. The max 17 Volt of that particular IC is also what drives the maximum number of leds that can be put in series. So for that IC it's 4 leds for white, green, blue and 6 leds for red. But if another driver IC or ready make affordable (!) brick happens to allow for a higher voltage, I'm happy to design for a larger number of LEDs in a string.

Any hints/tips/ideas much appreciated.


----------



## hank (Feb 11, 2012)

These are on closeout if you want to compare; search for "AxiomLED 630nm RED LED Grow Light"


----------



## pretmetled (Feb 11, 2012)

Thanks for the tip. Just took a look, but what I could find was pretty vague in terms of specifications. "LED light bulb is only 12 Watts compared to 75 Watt incandescent bulb" doesn't really tell me much regarding light output. Or maybe I didn't find the right items...


----------



## blasterman (Feb 11, 2012)

Not sure why all the colors are needed, but one suggestion is to look at LED PARs used for DJ lights; Chauvet, etc. Most are RGB, but many are RGB+W, and via DMX you can set individual channel intensity. That at least gets you into the power range you need with total channel control.


----------



## pretmetled (Feb 11, 2012)

Good point. Although ... do I even dare look at the prices for those things?


----------

