Custom DIY LED panel help

crunkyeah said:

Ohhh nice, thanks for stopping by! Just curious, when you were building your panels did you use the 3w or 5w diodes? Or were you using the 5mm and 10mm ones? I have done so many countless hours of research and I've found it never ends! But I don't mind, I think I may be a bit of a researcher by nature so it's all gravy.

There is simply no way I could use a 120v power supply. I'm assuming you mean AC too, since there are very very few DC power supplies that put out 120v. Trust me I've looked. The max I've found is about 100. The diodes that I'm using, they advise that they should be in strings or series no larger than 6. Even from a logical aspect this seems like a very smart thing to do. Let's say I've built my panel(which isn't the same as the last one I posted, I will update that after this post) and I have wired up 12 LEDs on one string. Let's say each runs at 3v and 350mA. First off, we're needing a power supply that has an output of at least 36v, and .35A. This is theoretically possible, but is not smart for a couple of reasons. 1, you're going to be paying for a good power supply and be drawing nearly no amps out of it. Kind of makes it pointless to buy a good supply and then not use it to it's potential. 2, if 1 LED in the string goes out, it will create an open circuit. Therefor if one LED goes out 11 more go out. Not a good situation if you have to wait weeks to get a new LED. Now if you have only 6 diodes, you will use 18v and draw once again .35A. If one goes out, only 5 more go out. I think we could both agree 6 LEDs going out are better than 12. Another thing about power supplies, laptop power supplies simply will not work without a current regulator on them. They have spikes in current, which raises voltage which lets more current in which increases voltage..you get the picture It creates a loop which will eventually overdrive the LEDs and fry them. I don't know where you got the batteries from, I have never thought about using batteries until I saw a solar panel setup... but that's another story!

Onto the viewing angle, I have actually decided to tighten up the optics on the LEDs. This will give me a more focused intense light on the canopy, so that more light isn't be reflected off the walls of my cab. This as we know from CFLs, MH, and HPS is not as intense as direct light.

Now for the heat..I WILL need to use both a good solid aluminum heatsink AND fans. I will be drawing 1.75A onto a panel that's 8.5" x 13". That's a lot of current to dissipate. Even if I didn't 'need' the fans, I would still add them because LED life and intensity increases the closer you can get to 0 degrees Celsius. The optimal temperature is 25C or 77F. In the room I have 73 is about the normal temperature, so I will obviously have higher temps running almost 2 amps through my panel. Thus the cooling fans.

And as for the spectrums, see in my next post.

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crunkyeah said:

Once more, the design for my custom LED panel has changed. This is mostly due to number crunching and looking at the data sheets for the Luxeon Rebel LEDs I'll be using. The biggest influence factor here is temperature. LEDs are more efficient at lower temperatures. What affects temperature in LEDs the most? Well being that LEDs are current driven devices...you guessed it! Current. So I have decided to cut the current in half, down to 350mA. In turn, this lowers voltage required to power the LEDs. Lower voltage and lower amps means lower watts. So the 60w panel I designed before, will now only be putting out 24.5w. To combat this, I will be adding 6 more LEDs to the mix.

Now for the spectrums part. I have since decided to not use both the orange spectrum and warm white spectrum. Orange because it has a tendency to create hermies, and white is simply not needed. So in total my spectrums will be 447.5, 465nm, 626nm, and 650nm. This doesn't have the important 660 spectrum, but I would have to totally redesign my panels with a different MFG and I decided that's too much work. Enough as it is

Onto the panel itself. The panel I have chosen is 8.5" by 13". I have chosen this length so that each LED has about 1 square inch of surface to dissipate heat all by itself. I don't want them too close, but too far either. I would use 2 inches between LEDs if I could afford the heatsink that big. The one I'm looking at is only 35 bucks or so, which isn't too bad. So the total surface area of this heat sink is .7 feet.

Now a bit about the optics. The LEDs have a standard viewing angle of 120 degrees. So if I built my panel and did not use optics, I have 2 options. Lower the panel down to my plants so the light isn't dispersed all over the place, losing efficiency. Or I could leave them higher up and have really stretchy plants. I have only 2 vertical feet to work with once you add in the pot size and thickness of the LED panel. So at 2 feet and 120 viewing angle I get a beam diameter of 6.9 feet. This is huge, this is twice the square footage of my grow area. So roughly half of the light will be reflected off the walls, losing more efficiency. Now if I use optics and tighten up the viewing angle to 12 degrees, I get a .42 feet(or 3 inches) spread from each LED. So now we're looking at a coverage area of 10" x 14.5". So this light will cover about a foot and a half of INTENSELY focused light. No light will be reflected off the walls(or very little light). I have told people it's the same exact aspect as a flashlight.

You can focus it to one really narrow bright beam or one really wide beam that covers the whole room. The really intense light is what you want. I hope people can understand my reasoning here. I'm working with a little more than 2 square footage in my cabinet, so to help out with the side lighting I will be adding my 4 LED panels to the sides of the cab to help with the undergrowth and to even out the light distribution.

Now onto the power supply and electrical stuff.
The red LEDs draw 2.9v @ 350mA, blues draw 3.15v @ 350mA.
I need to multiply times six for the number of LEDs I'm using per string. I use the blue LEDs because they have a higher voltage. 3.15 * 6 = 18.9
I will be using 5 string of LEDs, 4 red and 1 blue in the middle.
5 * .35A(350mA) = 1.75A

If you use Ohm's Law to calculate wattage:
Red - 2.9v * .35A = 1.015w(rounding to 1w)
Blue - 3.15 * .35 = 1.0125w(rounding to 1w)
Since I'll be using 30 total LEDs - 30 * 1w = 30w

So I need a power supply that has constant current capabilities, puts out at least 18.9v, 1.75A, and 30w.

I have found the Meanwell PLN-100-24. It puts out 24v at 4A, 96w. I used this one because it's current and voltage regulating. It will also be mounted near a fan to aid in cooling, and increase the life of the supply. It will also be operated at less than half of it's capabilities so I think it should last quite some time.

I have attached 4 pictures, 1 of a heat sink like the one I will be using, 1 of the power supply, 1 of the design on that heat sink, and 1 of the lens I'll be using.

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riddleme said:

solder is best, things like butt connectors will oxidize over time and cause problems, 16 gauge wire will be fine

soldering is actuially pretty easy to learn the key is to heat the joint and apply the solder to the joint (not the iron) as soon as it flows remove the iron, when I was teaching I had students make necklaces out of 1 inch pieces of wire by the time you get 20 to 30 of em soldered together you pretty much can see when it's good (right) also you want the solder to dry shinny if it is dull you got it too hot

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crunkyeah said:

Haha that's cool LEDs are so versatile you can do a lot with them. I think after this whole grow panel is complete I'm going to try and create some taillights for my vehicle made out of LEDs. I have thought about why they dont do this since I started driving - funny you say it out of now where And somehow put a pressure sensor on them so it pushes more current the harder you step on the brakes. So when you're slamming on them it's obvious to people behind you that they're on. And when you're slowing down slowly, it will be dimmer so it doesn't blind people. I've always wanted to do this I just need to work more with LEDs first.

Prolly right about the ma - In the pics I am intentionally out of the viewing angle - its not fun to look right at them. It is not as powerful as the commercial one fixed for my friend but it did great on the subject plant and went onto the wall to light the sides of the plants. The side of the room with the LED's on the wall def produced much better than the under canopy on the other side of the room. I had (2) 1k HPS in their so there wasnt a reason to mess with the LED's more than mounting them on the wall.

I believe those 5mm LEDs run at 20mA. That's the standard for most of them these days. I really like your design on the cardboard. It looks good for sure. You said that these were sufficient to grow a plant on their own? I mean no offense but it doesn't look like enough power is going into those to flower. I could be very wrong though I've seen some crazy low wattage grows that turn out decently.

I know how many you have - I almost threw a webpage together on how to DIY on these things because the price of the commercial ones are ridiculous

edit- And as for the bookmarks, you wouldn't believe how long my list is just from different LED manufacturers, let alone informational websites and other odd sites I've found on the net. I have like 150 bookmarks on my toolbar lol. I used to have them right under my URL address bar (use firefox) but I have collected so many I now have to view them like the history tab haha. I have like 6 or 7 different notepads for different types of LEDs and configurations too. Along with pdf files for data sheets for like my power supply, the LEDs I'm using, etc etc. It's really hard to keep track of sometimes! But at least I know it's all there

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btnhbizzy said:

Do Led harvests Yeild better then cfls? or hps?

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crunkyeah said:

I think that question needs some more variables. I think CFLs(enough of them) will yield better than a 90w UFO by itself if you hang the bulbs correctly. I think you really have to compare watts between LED and CFL. If you've got just as many watts, LED all the way. Say you've got 4-6 42w flower bulbs vs 1 90w UFO, I think the CFLs will do better, but that's just because you're turning more electricity into light.

So I think it's HPS > LED(enough watts) > CFL. As for cost...CFLs are definitely cheaper. I'm running ~272w of CFL, which cost about 50 bucks total since the big ones are spendy here. My 55 watts of LED panels cost 100(which I got a great deal on). So I think if one is on a budget and needs to keep electricity cheap, CFLs is the way to go. If you can go cheap and can handle the electricity, HPS is the better option. As long as you can vent the heat anyways.

LEDs are really expensive atm, it's hard to justify using just them unless you're doing a micro or some such. Just my $0.02.

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