LED grow lights... input please.

Discussion in 'Indoor Lighting' started by turtle420, Oct 12, 2005.

  1. Shadowskunkskankin

    Shadowskunkskankin Registered

    Led IS the way forwards :thumbsup:! But with out a doubt is there not enough penetration:mad: , undergrowth just doesn't get enough , you would have to have LEDs for all angles to get some REAL results. $$$$$$$$$$ :wtf:
  2. sideshowmel

    sideshowmel Registered

    To Psyz;

    Having made a lighting system of roughly the power you're considering, I thought you might like to know what I found to be the most difficult part of the design, which is cooling.

    A normal metal vapour lamp may produce more heat than an LED with the same number of optical watts in the PAR areas, but a metal vapour lamp can also withstand a lot more heat. A glass bulb can hit a couple of hundred degrees C without a problem, but an LED will start to lose brightness, efficiency and have a decreased lifetime if run at 60 or more.

    I believe this is probably the part most people get wrong.

    The biggest module I used was 50W, as a 7x7 grid of chips covered in silicone and mounted on a metal plate. I found two ways to keep the die temperature low enough. One is a cpu heatsink and fan (made of 5mm copper plate and 30 densely packed 1mm thick copper fins) which was designed to cool a 120w cpu. I ran the 12v fan fan at 7.5v as the heatsink was a little too big, so the noise level was better than full speed. The other was a natural convection heatsink (no fan) made of extruded aluminium with widely spaced fins. It measured about 20x15x5 cm. In both cases the led modules were stuck on with thermal epoxy. Small bolts, spring clips and thermal silicone grease would also work if you want them removable.

    If you are a decent plumber, and have the tools and inclination, soldering (very) flat copper plates onto square tube and running a convection loop full of water and anti corrosion fluid to an external (car?) radiator would also work well if people's water cooled pc projects are anything to go by.

    The bottom line is that LEDs need as much or more cooling per watt as CPUs do, because they need to run cooler to get full benefit from them.

    As far as the cost, electricity usage and so on, it depends partly on where you live. All of the waste energy from the lights is heat, so if you're in a cold climate the lights' waste can be taken off the cost of your heating bill (notwithstanding the difference in price between electricity and gas), as long as the lights' coolant air (or liquid) is separate from the enclosure where the smells are.
  3. sideshowmel

    sideshowmel Registered

    The circuit is not one I'd recommend. It won't be very efficient, as evidenced by the large (in relation to lamp wattage) resistor. That component is to turn "spare" electricity into heat. It would be better to use a switching regulator, although I haven't looked at what dc-dc circuits and parts are available. Even the crude hack of plugging in an inverter and running mains voltage LED power packs would probably be more efficient than a linear (big resistor) regulator in many situations.

    Chances are there's an ideal solution where you get LEDs in modules at voltages of multiples of minimum battery current and then use a constant current dc-dc converter with variable duty cycle pulse width modulation and solid state components.

    Regarding the red/blue ratio, the figures I calculated by comparing the absorption spectra of the known light-sensitive compounds to the surface sunlight spectrum are as follows;

    1 part uv
    5 parts blue (439 469)
    30 parts red (642)
    4 parts deep red (667)
    1 part infra red (735)

    The wavelengths are usually rounded to the nearest 5, so the options I saw at the time were; 365nm uv, 455nm blue, 640nm red 660nm deep red 735nm infra red.

    There is a problem though, because these figures are for optical watts, not electrical watts. For a complete calculation you also need the % efficiency of that wavelength and brand of LED (yep, they're all different) to work out how many electrical watts you need for each optical watt. If you're ordering cheap ones from china it's partly guesswork.

    As far as the colour balance at different points in the light cycle, it may make a difference, but I've seen no evidence of that (I invite references to any material which shows otherwise). I'd suggest the best way to achieve a change in ratio is to wired up the difference between the 'seasons' as separate circuits and switch one set off and on to vary. Making the whole lot dimmable seems like more complexity and inefficiency than it's worth.
  4. sideshowmel

    sideshowmel Registered

    One more thing, as far as I could tell, most researchers don't believe we know every frequency plants use. The methods used to discover what frequencies are absorbed by what substance, and whether the substance is altered by that absorption, are not precise enough to detect the light spectrum equivalent of 'micronutrients'. It is entirely possible that some obscure frequency is liked by plants as a fraction too small for us to yet detect. Therefore I have assumed in previous experiments it is sensible to mix in some broad spectrum whites, such as the daylight coloured ones with yellow phosphor on a blue chip.
  5. Weezard

    Weezard Registered+

    "The circuit is not one I'd recommend. It won't be very efficient, as evidenced by the large (in relation to lamp wattage) resistor. That component is to turn "spare" electricity into heat."

    Don't be misled by the resistor wattage.
    That is a "sense" resistor, and it's less than half an ohm.

    That component is used to create a voltage drop.
    V. = I. x R.
    0.47 Ω at 2A. = 0.94V.

    It is a tad oversized to limit it's heating.
    Heat increases resistance.

    That voltage drop is applied to the sense lead of a voltage regulator.
    But, because the sense voltage tracks the current, we have tricked a cheap voltage regulator into performing current regulation.

    In short, very little power is wasted in that resistor.
    Less than 2 Watts at 2 Amps
    P = I. x V.
    2.0A. x 0.94V. = 1.88W.
    This regulator circuit works very well with battery power.

    Just a couple 'lectronic pennies.


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  6. sideshowmel

    sideshowmel Registered

    2 Watts wastage seems acceptable, the more leds you had on it the less significant that would be.

    Now I look at the article properly I can see there are various different circuits described, the first being more in the way of an introductory "what not to do". Mainly I was just prejudiced by the unusually large resistor, should have read the whole thing first.

    The second to last configuration reminds me of something I used to drive the backlight leds on a phone screen.

    Very interesting, despite unfair first impression.
  7. sandylaser

    sandylaser Registered

    hi so what kind of light do you use currently?
  8. MG.Snake

    MG.Snake Registered

    i have dumb quetion. . .(idk anything about lamps)

    what is nm ???is that size of the LED lamp?

    whats differences between normal led and full spectrum led?
    can i just use normal LED Lights?
  9. PuffPuffPassDragon

    PuffPuffPassDragon Registered+

    So the most recent post dates back to 8/2012 - Where is current LED technology as it relates to MJ growth? Any recommendations?

  10. Weezard

    Weezard Registered+

    Um, partial spectrum/full spectrum and you are correct, these questions do border on dumb.
    Please read.

    Your last question is well answered right here, all you need do, is read it, yah?

    Aloha and good luck,
  11. Weezard

    Weezard Registered+

    Sorry brah, dunno.

    Once the hucksters arrived with the band wars, missing chords, super high-res dahoozit, horse exhaust, I moved on.
    Already had a light that worked very well so the rest is marketing hype.
    Still have that light, still working well!

    Who has time for hype?

    I'd say, look for a quality built, bi-chroic , array with at least one of the colors adjustable.
    Grows great buds.

  12. PuffPuffPassDragon

    PuffPuffPassDragon Registered+


    I can't find a dimmable Blue or Red LED array. I am thinking I may have to get 2 different LED banks (1 for veg [blue], 1 for flower[red]). I've read poor reviews for Dorm Lights G8. decent reviews re: Kind. Who is is out there in the LED Grow light world for MMJ/MJ?

  13. Weezard

    Weezard Registered+

    Left you a rep comment in the other thread.

    The last decent commercial light that I saw, was made by Lumigrow.
    Can't pimp it, because I haven't used it.
    But reviews and side by sides are very good.
    And they are still around!

    If I was in the market, and had any cash, it's the one I'd try.
    I do endorse the science of it

  14. PuffPuffPassDragon

    PuffPuffPassDragon Registered+


    Roger that, I will research Lumigrow.


  15. PuffPuffPassDragon

    PuffPuffPassDragon Registered+


    Roger that, I will research Lumigrow.

    So Lumigrow has the Pro 325 and the 650. So what area do you think the 325 could effectively grow? 650?


  16. THContent

    THContent Banned

    Dude don't go with LED's unless you like wasting money.... MH or HPS have always been second to the actual sun in regards to RESULTS that haven't been tampered with. MH combined with a cooltube to solve heating problems and bam, you got yourself some big ass buds.... LED's are energy savers but in the end you are gonna be smoking popcorn sized buds. Take it from me, read my threads and grow log and my DIY cooltube and you will be thanking me from saving you from the LED "marketers" that veg with MH and then throw up LED panels and say "hey look at the results I got with LED's". I give anyone that goes with my methods my word that you will see REAL results and you will spend less. Hands Dow LED's are good for the electric bill but not so much for growing, otherwise more people would not be going with MH and HPS hoods for their grow rooms. It's about quantity and quality, according to the plants I've grown they disagree with those that say that the MH and HPS are not within the spectrum of lighting needed, if that was true then why are my HPS buds whooping your LED buds hands down without question under the same conditions and nutes. I have a few of the high quality LED panels so I could do the comparison side by side and LED's should just stay inside modems and cable boxes because they don't show a damn worth of results in comparison or in price.... Don't try to rip off the newbies with your LED set ups because they won't give u results, and the noobs should ask about the return policy BEFORE purchasing and use PayPal so you don't get screwed!
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  17. Weezard

    Weezard Registered+

    I disagree.
    Based on my actual, personal experience.

    frosty.JPG Shut-in.jpg Sun vs LED.JPG 6 weeks under leds.JPG Led veg coco test.jpg

    Because I have flowered with HPs and I have flowered with LEDs, the right way.
    200 Watts of red and blue leds gave me larger, tighter , sweeter, buds than 400Watts of HPS.

    The third snap compares led buds with sunlit buds.
    That surprised me. We get some serious sunlight here.

    And my LED arrays have been in constant use for several years and are still as bright and effective as they were the first year.
    I grow excellent quality bud, I don't waste $$ on electricity, and I don't have to replace hot, pricey, bulbs every year.

    What's not to like?

    • Like Like x 2
  18. growdemon

    growdemon Registered+

    Yea I agree with Weezard, if anyone is reading this ancient thread. proof is in the pudding. Ignore what people say. and just try it.

    Here is with full power only 260w full draw. in a 3x3 2 lights 130w each. tested with a kilowatt thanks to Weezard


    Attached Files:

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  19. NextGenLed

    NextGenLed Registered+

    I have been testing LED panels for the last year! The next gen of indoor horticultural indoor lighting is single high powered chips(COBs) The Vero based panels with 3000K for straight flower or 4000K for the cycle! I started a youtube channel (LEDgrowlights) to guide growers through the ins/outs of the B.S that's thrown around. Cheap in the LED world usually means Inferior Chinamen panels! Here is some of the work Ive put in. Ive spent 7grand testing panels! The KINDK5 750 is a 430watt panel that grow very good with the added uv/IR but it uses way too much wattage for the coverage area. Next up was the Area51 RW150s a 2 of these covered the same area but with 310watts of Cree XTE and XPE. Then after this! 2 American LED companies contacted me wanting me to Test there VERO based units. heavenbright and opticgrowlights. There has been no looking back! These units are self serviceable units! No need to ever send a unit back for warranty. Send photo evidence of faulty part and they send u the part for repair. Each module is independently serviceable so the others will work until service is done. Never lose a fixture again! And the spectrum is best available. MeanWell /VERO and MADE IN USA with heatsinks/Fans/Cases imported from other areas of the world.
    In the pics
    ElementalSeeds HoneyBananas/GummyBears
    ReservaPrivada StrawBerryBanana/Tangie
    HumboltSeedOrg BlueBerryHeadBand/707TruthBand/GreenCrack
    EmeraldTriangle CottonCandyCane
    Enjoy! And if anyone has any questions for me? That's what I m here for!

    Attached Files:

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  20. Caribbean99

    Caribbean99 Registered+

    Thanks Grow Demon! I started my first grow and have 4 plants under T5s now in flowering phase and I've been researching the advantages of LED. Your post has confirmed what I've been thinking. I have a 3 x 3 tent with a combination of T5 HO and CFLs for about 20k of lumens (250 watts). HTG Supply in Ct. is offering a 432 watt 7 band LED for $199. If my math is correct that should give me about 30,000 lumens? In a 3 x 3 tent that should be enough, no?
    Also, would I hang overhead or come down at 90degree angle? How much sq. ft. area will that 432 watt LED cover?
    I understand the importance of the multi bands and I definitely don't want the electric bill to blow up and I'm also concerned about the infrared heat footprint. So far the T5s have not increased my bill much at all. I understand the LED uses even less and leaves no heat footprint detectable from the air? Dude got busted in the county I live in - using MH and HPS light in the attic. Spotted him from the air in copter. 50 plants. I'm not so worried about it but better safe than sorry. My grow is 4 - 8 plants for personal medical and recreational.

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