View Full Version : so i want to build an LED grow light
Powdered Toast Man please
06-02-2009, 07:46 PM
well first of all my computers keyboard is fucked up so their wont be much punctuation in this post sorry
well i have been looking into a cheap alternative for expensive growlights
from what ive read plants can grow under LED lights that emmit certain wavelengths
im probably going to be using over five thousand lights (i can buy in bulk)
im going to assume that this is not as easy as i think it is
i will be using a few different wavelengths too
im guessing i need more than just LED lights and a power source and thats why im here
what other electronic components am i going to need? and it would be helpful if some one could tell me how to assemble something like this on a small scale that can be proportionately scaled up or give me some sort of "formula" so i can figure this out and figure the costs my self
06-02-2009, 07:50 PM
06-02-2009, 10:57 PM
Good idea. LEDs don't radiate as much heat as conventional CCFL and gas discharge tubes, meaning you can maximise intensity by putting them closer to the plants. However, contrary to popular belief, high powered LEDs make significant amounts of heat at the junction and need to be cooled to stop them failing. For example, powerful LED torches have an aluminum heatsink inside...you could probably do with a fan or two aimed at the array. Oh, and I don't know a whole lot about growing, but here's what I do know...
That wonderful plant needs light in two wavelengths - 450 and 600nm, which is blue and red light respectively. From what I understand, blue is for chlorophyll production and red is growth stimulation and direction. CCFL and gas tubes are wideband emitters, meaning they kick out a many different wavelengths of light at the same time. This is in addition to IR, which is not needed by the plants...so all in all, quite a bit of the electrical energy is wasted. In contrast, LEDs are narrowband, meaning they emit a much narrower spectrum. Manufacturers typically specify one wavelength but in reality it varies around that, but plants aren't too picky. You will however have to match the LED wavelength with the peak absorption wavelengths mentioned earlier, so I'd assume an array like scovegner mentioned with equal amounts of blue and red LEDs would work well.
If you do plump for the pre-made PCB in that link - which I strongly recommend you do - be sure to use a regulated power supply to avoid frying your LEDs. Unregulated ones will output significantly over their rated voltage when under a light load.
The one gotcha is that bright LEDs are not cheap. A quality high intensity one runs about $1 each. You may be able to get away with cheaper superbright ones, but I advise you to do some testing before you buy a shitload of them...
Oh, and I'm moving this to DIY - it's more suited there. :)
06-03-2009, 05:27 AM
I'd hold off on an LED grow, unless you're doing it for shits and giggles.
I've seen one serious LED grow, and the guy got .38 g/watt, 3oz. at 220watts. He upscaled to 700w which cost $1500. Wait 10 years and everyone will be doing LEDs.
06-03-2009, 09:38 AM
Yeah i agree with the last post, LED's arent quite economical yet for the amount of lumens you need for plants. Just because HPS and CCFL emit over a wide spectrum doesnt mean they're worse off. The proper growing bulbs will peak at the right wavelengths, and taper off around those peaks - similar to the response of the chlorophyll. Its also arguably better to try to reproduce the sun's wide emission spectrum.
LED technology has been steadily advancing, they're even in some headlights now - but if youre serious about your budget you're best off getting a decent HPS in the meantime. By the time you invest in bulk LEDs, the necessary wiring, and power supply, you would have been better off dropping $150-200 on a small HPS (with ballast) that would be the right size for a closet grow.
06-03-2009, 09:49 PM
Off topic but on point. Vertical grow, enclosed light in glass tube that has a fan to take away the heat. Much more effcient than LEDs. I was in contact with a chinese LED company a few years ago with the hope of them manufacturing and me importing LED grow lights wholesale, but the sums didnt stack up against vertical growing. They say the future is bright tho.
06-05-2009, 02:38 AM
On a non-pot related note, is 450nm and 600nm specific to cannabis? Or is that a general rule for most greenish plants?
vBulletin® v3.8.1, Copyright ©2000-2013, Jelsoft Enterprises Ltd.