Building a LED Vertical Light for a homemade rotating garden

[Zimpon]

Hello folks

Its my first post here, in short im more of a machinist than a gardener and im building a rotating garden.

For you who dont know that a rotating garden is:

]

But the mail problem is the light, i want to bulid a cheap LED light that works. I know, i know, I know it is not two thinks that match. But I im assembling the LEDs so maybe i can cut the cost a bit.

I found this 3W LEDs from the usual bidding site.

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100pcs 3W Red 660nm Power LED 3watt for Plant Grow Light Lamp Bead

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100pcs 3W Red 660nm Power LED 3watt for Plant Grow Light

And i wondering if it could work to buy a few hundred from LEDs and arrange them in this fashion:

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Do any of you guys have any experience from buying LEDs? or do you know where I can find a reliable sorce for good LEDs? The supplier for good and bad LEDs are from china, but the question is where are they?

 

[Fuzzy Duck]

You want to look at qualitie brand name LEDS such bridgelux, epiled, epled to name a few... might be some ofters tho only takes a google search to find LED panel sellers & most decent firms normally state leds used

alibaba.com is another good site for picking up bulk materials also.


660Nm 3w led used as example - To get that spectrum of light requires 3w of power 99% don't use their real wattage of the LED so that spectrum of light is diffused or watered down with less wattage !

Thats about as much as i understand LEDs tho.


I'm pretty sure Hosebomber may well visit the thread he knows abit or 2 about lighting 'n' stuff

 

[Hosebomber]

Fuzzy is 100% correct. If you are not buying a huge quantity of LEDs Alibaba is one of the best sources. If you do not have a reflow oven most of the newer model LEDs will be a problem for you to mount. They are usually SMD under component mountable only. I'm referring to Luxeon Rebels, Cree XT XP XM, Osram, etc. You can purchase them on starboards (like your second link) which will make it doable tho. If this is your first LED build and you do not have dielectric coatings, soldier mask, circuit layout software, etc. I highly suggest using starboards with a little thermal paste under each mounted to your heat sink.

As for the layout in the forth picture. You have over 21% blue, which I feel is a bit much for flowering. You only have one wavelength of blue at 435nm. You may want to change some of those out for royal blue (455nm) and maybe a 475 or 480nm. I'm a firm believer in full spectra lighting and you are missing most accessory pigments. You could fix that with a few warm and cool whites. I could go into a lot more detail, but I don't have much time atm. Hope that information helps.

 

[H-factor]

I was also planning on build my own led light for my small grow box

 

[Zimpon]

Wah, thanx guys for your reply!

But man it got hard when you search for bridgelux, epiled, epled LEDs. But i will now give up yet!

but i question, I know that 3w LEDs are the best, but what about 1w or 10w LEDs? Are they worthless or are they still OK?

 

[Hosebomber]

Efficiency wise, 1 watt LEDs are still the best. However their radiant power output is lower so you get less penetration. There are people out there using 1 watt white only LEDs and getting pretty good results. The biggest thing is that you have to grow for the style of light you are using. If you are using 1 watt LEDs you have to either Scrog or use side lighting panels. Once you start getting into using 5 and 10 watt LEDs you are losing efficiency and producing more heat. While the amount of heat is still no where near that of an HID system, it's the thermal management of the diodes themselves that you have to deal with. Once your diodes start getting hot you lose even more efficiency and shorten the life of your LED.

 

[420]

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[Zimpon]

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Ye, now we are talking =)

It is hard to find LEDs buy your own thats good, on ebay or alibaba.

I noticed that the building part is not a problem, but the money...

the "1000W HPS LED Replacement Kit" or 390W LED kit is good. But with heatsink it will cost a lot! Im looking for a hexagon (or polygon) heatsink, that is inverted, so to speak. Like this, but with five or six flat surfaces that i can glue the LEDs.

But i cant find any heatsink that looks like this with flat surfaces...have anyone a better idé?


But that not it for my stupied ideas, here one more...

If i use this method i dont need to have a "heatsink", but just a plain hexagon, so long that the water is running. The question is how big water tank i need?

 

[Fuzzy Duck]

I'm total sure what heat sinks are made of these days but i'm pretty sure i've seen copper used !


Copper sheeting = custom made heat sink !

Might want to look at designs for optimal fin placement for air flow and a suitable fan for it.


Water cooled system sounds groovey tho ya can do that with domestic copper piping, chiller unit of some description

 

[Zimpon]

YE Fuzzy

I was just thinking about to making the heatsink in copper, thats pretty easy for me too make.

I was reading around the internet, and some say that a led gives 70% in heat. So if i have a 390w LED then i should get 273W in heat. But i think that i will manage with a 20liter tank and maybe a little fan on the LEDs.

Do you guys think that i can place the leds with a distance of 8mm?

 

[Hosebomber]

When you place LEDs that close together your junction temp. stays high at all times. You can do it but you will either have to lower the drive current drastically or have a super chiller for you water cooling system. 6061 or 6063 Al is generally what heat sinks are made of. If you are going to use copper use it as a core only. It conducts heat very well but doesn't dissipate well without having a large surface area (ie fin).

 

[Fuzzy Duck]

You could use copper piping from a local hardware store etc with water cooling system & pump plus reserva, make the reserva removable from design so you increase size if need be for greater cooling power or evn add chilling units to the design


Copper sheeting may be harder to track down tho but could prove worth while for a home made heat sink with air flow/fan cooling.


Some good design ideas worth playing around with


I'm not total sure of led heat & stuff... but i was playing around with some thoughts on another scale with same sort of issue's have a look at this link - Bulb heat - Watts to Btu to Celsius Calculation

You may find the linked calculators may prove useful in the maths used for a suitable cooling system.


8mm ah... well i don't see to much of a problem with that could be questionable if you wish to add lenses to the leds tho making them more of a focus beam this ultimatley leads to a distance problem of lights from plants tho !



Copper is very conductive also, so sound insulation of electrical bits is important.

 

[Fuzzy Duck]

6061 or 6063 Al is generally what heat sinks are made of. If you are going to use copper use it as a core only. It conducts heat very well but doesn't dissipate well without having a large surface area (ie fin).

Not sure where to get certain grade aluminum from or how easy it is work with ?


A copper core would suggest that its on the inside of the heat sink holding the majority of heat which is slowly released through the aluminum exterior of the heat sink via air cooling ?

 

[Fuzzy Duck]

Crude design of a cylinder copper core thing... yup fuzzys gone banana's

As leds require thermal paste to migrate heat to the heat sink of the aluminum exterior of the cylinder cooling tube this should migrate heat to the copper core which in turn, due to its poor heat dissipation values slowly release's heat or stores it.

With air flow channels surrounding the copper core & exterior aluminum tube cooling may be achieved ?

 

[Zimpon]

Thanx for your tips, n Fuzzy you are taking it to a new level.

Well i have dismantet tre computer with fans n heatsinks, i will try to use these on the copper hexagon. But if i need to cool the water i think i can use thermoelectric conductor (or wht it is called), they are cheap and if you pump in 100w to it. It takes away the same amout in heat.

 

[Fuzzy Duck]

I hope in the near future i'll see the design up 'n' running in a grow journal.


I'm even more intrigued how your are going to manage watering the system


Heat sink - Wikipedia

 

[Zimpon]

Interesting articel about heatsinks...

Hmm, the water system is REALLY simpel, the wheel rotates and the plats get water in a bath. The wheel will make a full turn each 45min.

 

[Zimpon]

You could use copper piping from a local hardware store etc with water cooling system & pump plus reserva, make the reserva removable from design so you increase size if need be for greater cooling power or evn add chilling units to the design


Copper sheeting may be harder to track down tho but could prove worth while for a home made heat sink with air flow/fan cooling.


Some good design ideas worth playing around with


I'm not total sure of led heat & stuff... but i was playing around with some thoughts on another scale with same sort of issue's have a look at this link - Bulb heat - Watts to Btu to Celsius Calculation

You may find the linked calculators may prove useful in the maths used for a suitable cooling system.


8mm ah... well i don't see to much of a problem with that could be questionable if you wish to add lenses to the leds tho making them more of a focus beam this ultimatley leads to a distance problem of lights from plants tho !



Copper is very conductive also, so sound insulation of electrical bits is important.

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So, if i have lenses, do you think that the distance to the plats (10-30cm) till be a problem with a 390w lamp?
I have been wondering the same thing, but i have seen a video. And they are using a 504w led.. And it seems to work...

 

[RainerRocks]

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[RainerRocks]

Zimpon

Can't you just get 4 long rectangle heatsinks and solder a couple of metal bars to each to form a circle then
insert some kind of rod inside (space created for rod insert by spreading out the rectangle heatsinks by soldering
the metal bars long enough to create this space) which will be attached to motor to rotate .

It would be very easy to have a fan hanging down right near the other end of this to help with heat.

Thermal contact is crucial so now you have 4 flat surfaces (Long Rectangle heatsinks ) to attached the LED's to .

I just guessing and that's what I came up with.