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Thread: LED plant lights?

  1. #9
    Eats genetically engineered tomatoes Sig's Avatar
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    How do you think something like this would work, for a closed box?

    http://www.cheapvegetablegardener.co...-grow-box.html
    Formerly known as Silenceisgod!

  2. #10
    sarracenia_X's Avatar
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    jesse: hmm... a not-so-deadly deathcube... i think i might want to try that. i was thinking about lighting a small terrarium or grow rack anyways, so i might want to try LEDs out. i have a soldering iron and am pretty good with it, so hooking up the LEDs wouldnt be a problem. now i would only need a driver, a heatsink, and of course, the LEDs themselves.

    ---------- Post added at 08:20 PM ---------- Previous post was at 08:14 PM ----------

    i just remembered, i have an old cpu heatsink in the basement, but unless i want to use it for the "lifecube" thing, i would need a metal plate of some sort, and attatch the heatsink to middle on the back.
    BTW those dews and the flytrap look great. i especialy like that notched sundew (it is Drosera schizandra, right?)

    ---------- Post added at 08:26 PM ---------- Previous post was at 08:20 PM ----------

    i actually have a reef tank (40 g), so i might also want to use LEDs there

    Or rather my brother has a reef tank, but i find it sooo awesome, i wish it was mine, and he might want to use my idea to use LEDs

  3. #11
    jesse's Avatar
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    Quote Originally Posted by Sig View Post
    How do you think something like this would work, for a closed box?

    http://www.cheapvegetablegardener.co...-grow-box.html
    Yes, that works OK for a few thousand operating hours,
    - if you use white and super-bright LEDs
    - if you place enough LEDs per area

    I'd say for light hungry species (Dionaea, Sarracenia seedlings) you will need around 3 low-power (operated @20 mA) LEDs per square inch, so for a 8" by 12" box = 96 square inch you'd need 3*96 = 288 LEDs.

    For less light demanding plants like D. capensis, D. schizandra, U. sandersonii maybe a little bit less LEDs. Such low-power LEDs have only very little lighting power per LED, so you need many of them.

    About the "closed box": Before putting plants into the box, I'd check the temperature in the box after the LEDs are operating a few hours. Perhaps you will have to place one or two holes of a proper diameters in the lid or the sidewalls to provide some ventilation/cooling.

    Unfortunately such cheap noname LEDs in chains of light from China have no big lifetime. They become darker after only a few thousand hours of operating time, or they become totally defective and stay dark. And if single LEDs in the light chain becomes defective, the light of the whole chain can be affected, like no light at all after only one defective LED. Or all LEDs glow much darker after only one LED in the chain has become a darker glowing. Or (as happened when I tested low-power LEDs): Most of the LEDs become much darker, only very few stay super-bright as they were initially.

    After one year of usage for plant lighting (that's about 5000 operating hours), my low-power LED installation was pure crap, no lighting power any more. My estimate is that more than 75% of the initial light/lumens have been lost within 5000 operating hours. So I cannot recommend low-power LEDs for plant lighting or you must replace them relative often.

    It's not worth to use low-power LEDs in high quantities, I think.

    On the other side: Quality high-power LEDs made by a brandname manufacturer are much better. Such high-power LEDs have a higher electrical efficiency, which means they make more light/lumen from the same electrical energy. And they last much longer without losing so much of their initial lighting power. Also you need much less of them and the headroom in the growing chamber needs only 0.4" of installation headroom. So for small lighting setups, they are nearly perfect.

    ---------- Post added at 12:10 PM ---------- Previous post was at 10:54 AM ----------

    Quote Originally Posted by sarracenia_X View Post
    jesse: hmm... a not-so-deadly deathcube... i think i might want to try that.
    I'd give it a try if you want to do a LED plant lighting experiment.

    Quote Originally Posted by sarracenia_X View Post
    i have a soldering iron and am pretty good with it, so hooking up the LEDs wouldnt be a problem. now i would only need a driver, a heatsink, and of course, the LEDs themselves.
    And some thermal 2-component glue to fix the LEDs on the heatsink.

    Quote Originally Posted by sarracenia_X View Post
    i just remembered, i have an old cpu heatsink in the basement, but unless i want to use it for the "lifecube" thing, i would need a metal plate of some sort, and attatch the heatsink to middle on the back.
    Here is what I use:

    Heatsink: I don't use fancy heatsinks, just simple flat aluminium plates, cut to size as needed. I glue the LEDs with its hex-star on the aluminium plate, ready for soldering the cables. I calculate with roughly 5 square inches of aluminium plate per 1 watt of LED lighting as a heatsink. The plate then gets hand-warm when the LEDs are in operation. The aluminium plate can be fixed to the lid of the box or mini-terrarium with glue or some screws. Or even with double-sided adhesive tape if the lid is flat as the plate.

    LEDs: Always buy pre-mounted LEDs on small "hex-star" plates, do not purchase pure "emitters" only! Also buy quality brands with a high lighting efficiency. For my LED lighting experiments I'm using mostly these "CREE XR-E cool-white" type LEDs, directly imported from HongKong:
    http://www.dealextreme.com/p/cree-xr...with-star-2395
    I don't know the customs regulations in your country, but here in Germany I can import things of around 30 USD worth per purchase without paying additional customs or sales taxes, so these are the cheapest way for me to purchase good LEDs at a reasonable price. When ordering 3+ and clicking the "bulkrate" option at Dealextreme, they will send the LEDs by registered mail. Time of delivery to Germany is around four weeks in average.

    Thermal glue: Don't purchase the "grease like" thing, you need a 2-component glue instead. Until now I mostly used a relatively expensive "2-component thermal glue", but as I power my LEDs mostly with 350 mA only (that's much less than the maximum rating for Cree XR-E) I will use another cheap all-purpuse 2-component glue in future.

    Soldering: LEDs are diods, so you must observe + and -, don't mix it up.

    Driver: Always use "constant current drivers" and no fixed voltage adapters with LEDs. The constant current drivers at Dealextreme are cheap, but pure crap. Buy the LEDs there if you have no other cheap source, but don't buy constant current drivers at them. Here I use some very nice insulated drivers that I can directly connect to EU 230 volt mains power that need no extra casing or extra AC/DC adapter. If you need a driver recommendation, please name me one or two web addresses of Internet shops with LED equipment and I can lookup what is suitable. Unfortunately I cannot find suitable LED shops in the US when using Google-search from Germany.

    Quote Originally Posted by sarracenia_X View Post
    BTW those dews and the flytrap look great. i especialy like that notched sundew (it is Drosera schizandra, right?)
    Yes, it's a D. schizandra. Needs very high air humidity in its box.
    The other sundew is a Drosera spatulata 'Tamlin'. Needs much less humidity.

    Quote Originally Posted by sarracenia_X View Post
    i actually have a reef tank (40 g), so i might also want to use LEDs there
    In bigger setups you better use fluorescent lights plus optimized reflectors. My biggest LED setup for a small terrarium with pots standing in it is 60 litres, that is 16 US gallons. The more LEDs you use in a lighting setup, the more LEDs become defective. If you read in a LED specification "lifetime 25.000 hours" this doesn't mean that each LED has a lifetime of 25.000 hours, it means that after 25.000 hours half of the LEDs have become defective or lost much of their initial lumens. So you may come to the point if you have installed 10 LEDs that after one year of operation @14 hours lighting period (= 5000 hours in one year) indeed 1 of 10 LEDs have become defective and needs replacement.

  4. #12

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    I personally think LED's will be a dead technology for horticultural purposes. The future is plasma fer sure! They're currently WAY too expensive but the pricing will come down in the not-so-distant future. Check this link: http://www.plasma-i.com/lg-plasma.htm Look at the wavelength chart at the bottom of the page. Notice it's more of a curve rather than the "spikey" charts you see for HID, flouro, LED.

    And just to let all peeps know I'm not talking out of my hat: I work at an irrigation supply store that dabbles in selling indoor growing supplies for those "tomato" growers here in California.

  5. #13
    jerrysmith's Avatar
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    I have a friend that is a member of our Aquatic Plant club and he has built a couple of LED fixtures using CREE LED's. He gave a photo step by step on his blog site. Plus there is other information there too. I am going to have him make me one for one of my aquariums. This link is to part 1 of 5 parts. http://aquariums.seaspraydesigns.biz...ghting-part-i/

    CREE LED's http://www.cree.com/products/xlamp_xml.asp

    Heatsinks http://www.heatsinkusa.com/

    Cooling Fans http://www.coolerguys.com/

    These guys use CREE LED's http://www.stealthgrow.com/index.htm

    Here is an interesting site on Inductive Flourescent lightiing. There is even a Youtube video with one of their lamps being powered up under water. http://www.inda-gro.com/
    Jerry Smith
    Bloomingdale, NJ
    My plants: http://www.terraforums.com/forums/sh...d.php?t=128718

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