Advise needed on LED lighting (for a PC case grow)

[xil]

hey guys, nice forum you have here, im basically reposting my thread here since no one would answer me on GC. Any input apreciated greatly


im currently getting all the gear i need for growing 1 plant in a PC case, obviously this is a stealth operation.

i will buy the leds on ebay mainly.

so question number 1: has anyone had experience with china LEDs ? for example:
http://www.ebay.com/itm/10PCS-3W-High-Power-Red-LED-Light-Emitter-610-630NM-with-20mm-Star-Heatsink-/141036688187?pt=LH_DefaultDomain_0&hash=item20d671133b&afsrc=1

most of what i find on ebay are no name brands.. so concerns with quality are an issue, efficiency probably not so great either. maybe you guys know some good price to quality brands etc ?

question 2: I think i will go with blue and red leds with ratio something like 3.5 red : 1 blue. any input appreciated, and the spectrums will be 10 led 630 nm 10 led 650 nm and 6 led 455 nm. all are supposedly "3w chips" but really they are more like 1.2w for red and 1.8w for blue. Still my array will be of ~37W.

Question 3: power supply and current control (if needed) ? I planed to use a constant current driver to power the array (maybe 2 for each half of the array, depends on what i find, open to suggestions) once again, im thinking about a china made driver, do you guys approve this idea ?


Question 4: do you believe that a heatsink is necessary for a 37W led array ? i thought maybe just to put each led on a larger copper plate and attach that to the top of my PC case ? BTW the leds i plan to buy already have their own "star" shaped heat sink

currently on the shopping list:
10 osram golden dragon 630 nm leds
10 no name brand 650 nm leds (link above most likely)
6 455 nm blue china made leds

all of those leds are rated for 700 mA max, i plan to run them on 600 mA.



any extra input greatly appreciated ! thanks people

 

[monoclepop]

Blue is the dangerous colour - with too much blue energy you'll be running the risk of bleaching. But you'll definitely need an amount of blue - red light triggers stretching and you're trying to keep everything inside a tiny case. I've stayed away from specific coloured emitters I'm sorry so I'm not able to give you much insight into your proposed ratio. Though if you have two seperate drivers it would let you flip one off if you wanted to lower the amount of red forinstance to reduce stretch

The issue with ebay emitters is they aren't very efficient. Reds in particular lose efficiency as temperature increases. You'll definitely need some sort of heatsink, though the size/style really depends on how much air it has flowing over it. You will need ventilation for your plant's sake anyway, so perhaps you could combine emitter cooling and case venting?

If I were building a cheap PC case array I'd pair a couple of Bridgelux Vero10 or Vero13 in warm white (3500k-4000k - from Mouser or Newark) with some $6 drivers from Ebay or Fasttech. But there's no right or wrong thing to do here. Get googling on Vero grows and have a read of some of the research that's going on regarding using them - insanely cheap emitters with great efficiency.


Taking a look at what you're planning - given everything is so damn cheap from ebay it sounds like you're on the right track for a succesful build. What you wont get is efficiency, at least compared to higher end emitters.

Before jumping into soldering a bunch of cheap Chinese 20mm red and blue stars I'd say to consider LED bulbs (cree), consider warm white emitters (cree and bridgelux), consider arrays (Vero and CXA), and consider more efficient emitters (XML, XPG, XTE etc). All will have pros and con$ - and you're probably feeling overwhelmed already. Welcome to the nightmare of DIY LED, lol.

Consider a grow setup a work in progress too - I'm upgrading my micro-cab for the third time. From CFL->PLL->LED. Building a cheap chinese array might be the perfect place to start for you and can let you experiment without big overheads.

 

[xil]

hey man, thanks for answering

yea this is a cheapo build (will be my first grow). luckily i found them osram leds for cheap, so atleast 10/26 will be of higher quality.

but what do you mean by bleaching with too much blue ? as ive understood blue is very important for veg state, makes the plant grow wider instead of taller. and everywhere people are using ratios of blue to red like 1:3 or 1:4 (for full cycle lighting solution)

concerning the white lights, i did my research and i deem the white not being worthy (its basically a blue led with phosphorus added, still lacks a lot of red spectrum for flowering)

and yes, im thinking of adding a means to controll the current of the lights. concerning efficiency the blue china leds should do just fine i hope, i dont need much blue anyway the plant will veg for a short time due to space limitations. and i will scrog the hell out of it. the reds on the other hand have ~simmilar lumen output to osram leds (if im to believe the info on ebay).

i will put as big of a fan as i can in the top part (side of the light) going for 120mm if i find one, also i could put a second fan on the other top side, but the carbon filter would have to be outside the box, meaning after the fan (is there a difference in putting it before or after the fan?)

cant find any heatsink, but the leds will run at lower current than their max capabilities (0.6A) so i really hope a fat copper plate with bent sides for each led will do the trick.

but a question remains, can i trust a chinese power supply ? lets say i buy a 50W with 1.2 A current + make the leds in 2 series (since i cant find any supply with voltages of 70V max, i need ~67V if all 26 leds are in 1 series) do i need some form of controll for it, since leds will draw up to 38W total.

P.S. could i power the fans from the same supply ? if no, what is the best solution for them ?

sorry for the text wall

 

[monoclepop]

hey man, thanks for answering

but what do you mean by bleaching with too much blue ? as ive understood blue is very important for veg state, makes the plant grow wider instead of taller. and everywhere people are using ratios of blue to red like 1:3 or 1:4 (for full cycle lighting solution)

The blue frequencies tend to be the ones responsible for bleaching - the short wavelength really does plants in at too high a dose. The distance you need to space your lights from the plants is something to think about - especially in a wee cab where a few inches are precious. It might take a bit of experimenting with grow style as well as changing up your LED spectrum to get a sweet spot for a particular case and genetics.

You definitely need blue - how much? Your guess is as good a guess as any. It is all a bit of a guess right now - people are getting good results with all sorts of things, and technology is changing very rapidly.

Have you seen some decent grows you want to emulate?

Sample heatsink:
http://www.ebay.com/itm/60x150x25mm...ED-and-Power-IC-Transistor-H148-/200800824597
http://www.ebay.com/itm/90x90x15mm-...or-LED-Power-IC-Transistor-H130-/200800913775


PC fan is 12V DC, but you can run them lower. 120mm sized is great, 80mm is ok - slow and silent are best. Grab anything from an 8V to a 12V dc adapter from goodwill if you don't have one from an old cordless phone or something, or buy an adjustible DC voltage adapter if you want to be able to change it on the fly.

Don't sweat it on the grow - it's a weed. Stick it in dirt, put any old light on it, feed it water and a small amount of food and it'll get there for you. More light good, some fresh air. You have to work pretty hard not to at least partially succeed. Then comes the very long process of trying to improve a ridiculous growing environment that is a microcab!

Chinese supplies: run slightly hot, plenty of EMI, lower than rated output. Keep in mind as you proceed. I'm adding a fuse and a MOV before my LED drivers - a big spike will quickly blow the MOV which will burn the fuse out. Pennies worth of parts worth considering if you're worried about dodgy drivers. Add a fuse at least: I've never seen a chinese led driver in the flesh, but I'd rather put in an unnecessary fuse than not. I am nervous about fire - electricity, inexperience and weed is a heady combination.


https://www.icmag.com/ic/showthread.php?t=253160 - is a brilliant thread of a noob building a great panel that eats any commercial panel alive. Plenty of valuable info in terms of every part of design and execution.

 

[xil]

hey man, thanks again for the input.


ok, so i got everything i need figured out except for the power supply.

The problem is that if all 26 leds are in 1 series, i need a very high voltage out power supply (67-70 Volts). I planned to get a constant current one with 0.6A output, but i cant find such high voltage on ebay.

So, i could connect the array in 2 series, but those leds have quite big variation in f. voltage drop so that could easily lead to a higher current in one of the series, then leds get hotter and eat more current while other part gets dimmed and this goes on until they burn out from over current. Does any1 know what sort of "regulator" could fix this ?

Or can i go with 2 series and constant voltage supply then add a constant current driver in front of each series ? Then id need ~35-38V supply, maybe it would be easier to find

 

[hempfield]

This type of LED driver is what you are looking for :

http://www.ebay.com/itm/75W-LED-Driver-Power-Supply-for-18-25-x-3W-LED-100-240V-/390525452203

But remember the old say : don't put all your eggs on the same basket. If the driver fails, your panel will go off. I would use 2 drivers instead of a more powerful one.

And remember : you can't have constant current and constant voltage in the same time . LEDs need constant current, so the voltage will vary base on multiple factors.

For your safety, if you can accidentaly touch the soldering points of the LEDs, don't work with drivers that have an output voltage above 48V because it can kill you or cause serious electric shock.

 

[xil]

thanks for the answers guys. I thought about using 2 drivers, still am considering it.

But someone suggested me this:
http://www.alibaba.com/product-gs/1332941678/perfect_diy_LED_grow_light_source.html


its quite tempting to get the 50w pannel if the price is right. Only i dont know the wiring in the chip. may be that if 1 diode blows- everything blows. and that sucks, since i wont be able to replace individual leds. thats the only concern. I could run it at a much lower current though. maybe prolong its life

 

[hempfield]

There is no good way or bad way to go with leds. You only have the chance to test and learn. I am using cheap chinese leds for about 4 years and not even one single chip has died since then.

For simplicity I would go for one single COB led like this (same vendor, but individual listing) : http://www.ebay.com/itm/hotFree-shi...d-grow-LED-best-for-plants-grow-/261323916911

 

[xil]

i think i will still go with my original idea of 26 led array. At least its a bit more fool proof. And takes less space. With the diy kit i would probably mount the whole fan-heatsink-lamp fixture in the top corner of the pc and try to do scroging at an angle lol. More hassle than just simple lighting from above

Unless the vendor responds to me about 50w panel price and it turns out to be cheaper than my setup

 

[xil]

so, it costs 70$ for a 50w kit.

the price of all components separately is ~the same. But i do wonder if this "50 w" is just what they say or the actual draw o the panel..

 

[hempfield]

On a 50W COB LED there are 50x 1W chips. Usually each of this chips draws ~0.75-0.9W (depending on chip color and the value of the current - which for most of the situations is set at 350mA) .

I can't find the specs for the 50W COB, but we can do the math for the 72W :

Power:72W
LED chip Qty:72pcs
Current:2.1A
Voltage:27-32V

The real power is calculated with the formula P=V*I, where V is the voltage and I is the current.

For 72W COB, the real power can vary between 2.1*27=56.7W to 2.1*32=67.2W

So a 50W COB will draw somewhere near ~42W of real power.

 

[xil]

believe it or not i know some physics but thanks anyway

the thing is i dont trust their "rated" stats. and the 50w chip (from the photo i saw at least) was with way less than 50 diodes, more like 20-25. could have been a wrong photo too.

its such a guessing game with this chinese stuff..

P.S. i just found out they dont offer free shipping so.. its cheaper to make my own array anyhow

 

[xil]

sorry for double post. why cant i edit the posts :/ ?

i found this thing, cheaper, free shipping, only no heatsink/ fan
http://www.aliexpress.com/store/pro...lb-For-Coral-reefs-and/504331_1425691739.html

i think this is a better option than a single blazing hot integrated chip. They also have a 60w kit for the same price, it uses 2 power supply units. They say that the supply units are dimmable (they even add potentiometers). Though no info on the leds/ their voltage. only that they are "bridgelux" supposedly