Please explain LED cooling ...

Discussion in 'Lighting' started by SamOhio, Feb 14, 2014.

  1. From the few pics I have seen it seems like the large LEDs have one or more built in fans, correct? Are they noisey?  How does the heat compare to a equal sized bank of t5's? My tent is 36/36/60, would a large computer fan be enough to vent the tent?

  2. Nevermind I posted before I researched. Looks like I want the 10w CREE XML for about $600. I also read the thread where LEDs  generate little heat at all. I'm sold.
  3. that aint true bro. Leds get stupid hot. And a hot led is a quick dying led, the temperature of the junction (between the casing of the diode and the heatsink) should not get higher than 50 deg celcius. for optimal  operation. Thats why you need heatsinks. And a 10w LED needs a huge heatsink, since thats a lot of power concentrated in a very small area.
  4. Ok I understand. How do leds work with plant distance to the light. I'm growing in an attic so not much height, I hoped I could let the tops get pretty close to a properly cooled led. Just wondering because I seem to be reading to keep plants 24" from the light. If I could grow to within 12" it would be better. The space is air conditioned and kept cool.
  5. You can put leds very close to the plants. The good part is that whatever heat leds produce, they send it out the back of the diode, because the diode is enclosed by a polymer shell/ lens/ what ever which is a bad heat conductor, so naturally the heat goes the easier path to the heatsink and thus your lamp is not putting out heat directly on your plants
    I'd say 6 inches from the plants can be done, depends on the power of the light though.
  6. Thanks for the quick reply. I just collected links and I'm gonna see what's available. The only unit I've seen so far is 350 watts for $1000. I just need to cover a 5' x 5'.
  7. that price is bull :D
    just make it yer self, really easy and much cheaper. for a 5' by 5' i would probably get multiple smaller lamps maybe 3 or 4, depends. Leds are very directional, another advantage, but if you want to cover that area with 1 panel only, you will need to hold it very high above the plants, so you loose quite a bit of intensity, by raising a lamp 2x from the plants you lower the light intensity 4 times (inverse square)
  8. The $1000 unit is the only one I can find that utilizes 10 watt lamps. I see the ones using 3 & 5 watt lamps are much less expensive. I just figure the more light the better and see LEDs to be somewhat like HIDs in that the greater the wattage the better. Does anyone have a 10 watt unit they can compare to those with less wattage?
  9. OK seems I can buy a 20 watt unit too for half the price stated above. I'm really sold on these things and have started moving stuff to replace a hps 600 looks like with about 400 watts. Will make up my mind and order something this week.
  10. Make sure you know for sure what kind of LED you're buying. Most old school growers believe LEDs don't work, but the biggest reason is people have no idea HOW they work.  They're not supposed to be "bright".  Read this and make an informed decision:
  11. You can't have 10w diodes 6inches from the plants. If you wanna go that close you have to go with 3w or 5w tops imo. LEDs can and will bleach your plants if you have them too close. Don't underestimate them.
  12. Thanks for the replies I measured my space and figure I can leave about 12-16" of distance from LED to plant so I think I can go with the medium higher wattage. The unit linked above has fans pointing out the sides and that's much better than blowing out of the top in my case, space above the light will be limited. Only drawback seems to be price, guess I've gotta pay about $500 to get started.
    Hey I'm the new guy here  I've gotta ask a maybe dumb question. Has anyone thought about putting an LED on a light track?
  13. light track has been done. dont remember by who. But who cares, no reason why you couldnt do that.
    lol duude, dont look at lamps made from 10w diodes... you dont need that, one main reason is that lower wattage leds are more efficient (you get more light per watt of power used). 1w are the most efficient, but lamps need a crap load of them so most makers go with the optimal 3w diodes.
    and the light, i suggest to not look at white leds as im pretty sure you might be doing, talking about 10w diodes and stuff... when going led, you only need RED and BLUE, ratio varies between 3:1 to 5:1 (red:blue). so look at diodes 450nm for blue and 630/660 for red also you want some deeper red if you can find (like 700 nm) but NOT infra red. The 700nm spectrum combined with 660 induces emmerson effect= bettwer growth. I read that this also works while using 630nm with 660 nm leds, but to a lesser extent
  14. [SIZE=medium]After review of larger LEDs I've gotta say that in an attic I've still gotta find a way to use the heat in winter and vent it in summer just like HID. Anybody look at the Black Dog units the one I want, 450 something,  runs $1200 just like all the other distributers.  I'm gonna do this … I'm in the peak of a tall attic and I just took  out a light track so now I have room to run a 6” duct right along the peak. The LED then, no matter how much heat it generates, fits right into the duct to a small blower and I can either vent heat back into the room in winter or out in summer while ac is running.  That settles my heat question and leaves using the light track unanswered for now. I can extend this grow from 4x4 to 4x40 btw so that's why I'm thinking bigger.[/SIZE]
    [SIZE=medium]I've also settled my question of distance to plant tip seems to be 18”-24” recommended for the larger fixtures looks like I'll still be leaning and tying them down to utilize about 3' of height then just like with a cooltube.  [/SIZE]
    [SIZE=medium]Onward through the fog. Got it down to 5 links gotta pick from what's an actual 4-600 watt draw I guess and string them across the peak. If I'm gonna do one this way I may as well order two while i got the cc out.  I've got some LSD from Barneys which if I recall finishes at about 3' so trial grow beans are already reserved.  Not worried about weed but wanna get something running by early March if I still have cold temps to test heating benefit of LEDs with a thermostat as Spring approaches. I heat/cool the whole space all winter with a 600 HPS the space heater doesn't even come on, but with LEDs I won't have enough heat, I'm guessing. [/SIZE]
  15. Noob question: I've seen LED technology really advance in the realm of flashlights and vehicle lights. This article you linked states that LED's are good for flashlights but not good for growing, (except for the correct arrangement they are selling) I don't know enough to argue, and I look forward to the idea of LED technology advancement.
    My question at the moment is, what would be wrong with using an LED flashlight to dink around in the dark room during the lights off period? I'm getting the impression that it makes no difference as long as you don't hold the light right up to the bud.
    Any knowledge or even theories to ponder?
  16. I just ordered two Solarstorm 400s from Cali Lightworks. I'll make this thing about a 3x6 now for starters. Guy just asked my ? in above post about exausting these things into ducting I'll kept an eye on it.
  17.  Yea, that would be bad if you play it safe, well its like gambling really, you take the risk of getting hermied plants, any light disturbance might lead to this.
    @[member="SamOhio"], damn mister, you have one cool set up ! With that kind of venting system you are so ready for this. Good luck
    Cool keep us updated!
    Heat is my enemy, if these things run cool(er) it could be the difference between going HPS or LED for my next lights.
  19. I'm no expert yet just from reading but these things gotta be much cooler. I've run winter grows in this space for years but May-Sept (Ohio) I've always had to shut down due to heat. Anyhow I put the light track back up, secured to peak, now it's under removable 6" flex duct to exaust up to three large LEDs. I can easily switch from LED, say May through October, to HID the winter months for free heat (well amost). I'll just leave the ducting for both systems in place.
  20. You can check out the heat manifold I designed for use with my SS800.
    (click on the link in sig)

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