LEDs in a PC case, setting up a light

[JH151399-OG]

Hi all. I searching for information on building my own LED light for an enclosure that has a footprint of 24"x9.25", a total of juuuust over 1.5 square feet.

I have two designs for lights, both with a roughly 5:1 red:blue ratio.

The first has a total of 15 lights, 6 red, 6 deep red, and 3 blues driven at 600ma for a total wattage of 23w.

The second has a total of 24 lights, 12 red, 6 deep red, and 4 blues driven at 600ma for a total wattage of 33.5w.

My question is, would the 23 w light be too little and/0r would the 33.5w be too much? The heatsink I am planning on using is 5.5"x9" for the small, and 5.5"x11" (possibly x12") for the large, not that the physical dimensions matter too terribly much. I'm more concerned with light coverage and intensity.

Thanks for your help!

 

[alkalien]

I have done a PC Case grow with 60 or 75W forgot what exactly it was. Went fine. So I would go with the bigger one!

If I were you, I would also throw in two white LEDs, just to get the enhanced spektrum and so you can watch your plants better. No green, I figured, makes you feel blind after a short time of looking into the case.

The best thing about high power LEDs in a PC is, that because of the high intensity, you don't need to worry about height. The plants just stop growing if they are too close to the lights

 

[JH151399-OG]

If I add whites, it will be pushing the larger array to 63v and 37.8 watts total. The red string will require 41v and 24.84w and the white/blue string 21.6v and 12.96w. Where can I find power supplies able to deliver those figures?

For the smaller (23w) array, the red string requires 27.6v and 16.5w, the blue string requires 10.8v and 6.48w. Similarly, where would I find power supplies for that?

 

[OverEagerBeaver]

If I were you I would get the bigger heatsink and run my reds leds and blues leds on separate dimmable drivers, I like meanwell, that way you'll be able to tune your spectrum for either veg or bloom or saturation. I would also recommend your red ratio be more far red, like 10 660 to 2 625.

What leds are you going to use? I've been using Osram GD + 660 and 625 for my reds and I just upgraded my light to Cree XT-e royal blue leds. I highly recommend both, but especially the Cree's, their cheap and incredibly efficient.

For all practical purposes with top bin leds I think you'll reach light saturation around 28 watts without the addition of co2.

Sounds like a fun project, good luck and have fun.
OEB

 

[setaemies]

I would also recommend your red ratio be more far red, like 10 660 to 2 620

For all practical purposes with top bin leds I think you'll reach light saturation around 28 watts without the addition of co2.

Sounds like a fun project, good luck and have fun.
OEB

Hi, is there a particular reason you prefer that ratio between red and deep red? What do you consider as a sign of light saturation?

 

[OverEagerBeaver]

660 is absorbed more efficiently than 625, more bang for your buck in terms of photosynthetic response, 625 is still absorbed well and helps fill out the red range but I would make 660 my primary and 625 a secondary.

 

[devilgoob]

Orange-red leds with more photosynthetically active radiation at same wattage are better, even though 660 hits peak absorption wave peak of chlorophyll, the Orange-red are still better because they have more light.

 

[JH151399-OG]

OK, Revised set-up. Let me know what you think.

DR (10) 2.3v x 600ma
13.8w
RD (6) 2.3v x 600ma
8.28w
RB (3) 3.6v x 600ma
6.48w
White (2) 3.6v x 600ma
4.32w

R/DR String
36.8v 24.84w
RB/W String
18v 10.8w

54.8v 35.6 total watts

-or-

DR (10) 2.3v x 400ma
9.2w 23v
RD (6) 2.3v x 400ma
5.52w 13.8v
RB (3) 3.6v x 700ma
7.56w 10.8v
White (2) 3.6v x 700ma
5.04w 7.2v

R/DR String
136.8v 4.72w
RB/White String
18v 12.6w

27.32 Total Watts 54.8v

Where can I find drivers able to deliver these numbers? Please?

As far as which LED's do I plan on using, the LEDs from ledgroupbuy dot com. The reds are CREE XP-E reds, 6001 bin. The RB, Whites, and Deep Reds are all Bridgelux.

 

[trem0lo]

Hey JH1, looks like you've gotten some great advice already.

Meanwell drivers seem to be the go-to brand for DIYers who aren't tech saavy enough to make our own. They're reliable, fairly cheap and come in plenty of flavors.

I personally use two LPC-35-700s which deliver a constant 700mA up to 48V. It would easily drive your bigger string if you didn't mind making your heatsink a bit bigger or throwing an extra fan at it to compensate for the extra 100mA. I believe they make a number of 500mA drivers as well... not sure about 600 though. They do make one with an adjustable pot to control the current as you like, too. The ELN-60-48 is like the LPC, except that it's adjustable from 0-1.3A.

 

[JH151399-OG]

Ok, I think I've finalized the layout. The case is actually quite a bit smaller than they advertised it as. The actual dimensions are 8.5x20.5x18 IN, with interior dimensions of 7 3/4" x 19" x 17 1/4" (WxDxH). That gives me Right at 1 square foot of growing room.

DR (10) 2.3v x 350ma @ 8.05w 23v
RD (6) 2.3v x 350ma @ 4.83w 13.8v
RB (3) 3.6v x 700ma @ 7.56w 10.8v
White (2) 3.6v x 700ma @ 5.04w 7.2v

R/DR String @ 12.88w 36.8v
RB/White String @ 12.6w 18v

Total of 25.48w

350ma Meanwell
LPC-20-350 $11.67
700ma MeanWell
LPC-20-700 $11.67

I thought about driving the DR/R string at 420ma, but that driver costs twice as much as the 350ma and the seeing as the case is only 1 sq ft... It doesn't seem worth it for the extra 3.1 watts (28.6 total watts @ 420ma/700ma).


Thank you all for your help!

 

[JH151399-OG]

I'd like to thank all of you for your immense help, but after weighing the cost/benefit ratio I've decided to go with some CFL's for now... who knows, though? In a year or two LED's may come down in price so ridiculously I'll make one anyway and toss her in there. Again, I really do appreciate the ICMag community.