LED Grow Light Using Joule Thief Battery Power in a Wick Gardening Container for CHEAP!





Introduction: LED Grow Light Using Joule Thief Battery Power in a Wick Gardening Container for CHEAP!

About: I enjoy growing citrus plants, building things that capture green energy, constructing car audio systems, and nearly any DIY project.

So the title has a lot of words in it, but that is because this instructable combines many ideas from many sources. The general idea stemmed from robomaniac's Desktop energy seed lamp combined with }{itch's Growing Plants With LED Lights instructable as well as the many different wick gardening planters that have been posted, but I saw it from whamodyne first (all these ideas are awesome by the way!). I wanted to build an LED grow light that ran off batteries because:

1. I'm a nerd.
2. I wanted citrus plants but I live in an apartment with horrible "sunlight accommodations" in Iowa City, Iowa. Citrus plants require a lot of sunlight and this week alone it's been cloudy almost every day.
3. I live in a college town so anything left outside either gets stolen, broken or thrown up on so growing them inside is a must.

Those are my reasons, maybe you have a few of your own but before going any further I must say that if you're going to use this information to grow pot I will not be held responsible for your drug habits if you are caught. Like I said, I'm using this to start up my lemon, grapefruit and orange seedlings, which last time I checked was perfectly legal.

Referenced instructables:

Oh and one of the battery terminals I used came from the design by xtank5:
thanks for that idea too!

Step 1: Materials

What you will need are these items, you can improvise if you have similar ones (that's what instructables is pretty much all about) but if you have electrical questions about the resistors or transistors please don't expect too much from me. I have a degree in evolutionary biology, not electrical engineering so hopefully if there are questions about the electrical aspects the group (or the people I referenced) will be able to help out. Anyway, here was the list of what I used:

25 x red LEDs (cheap ones off ebay, **see bottom for important details**)
5 x blue LEDs (same)
2 x ferrite beads
2 x 1K resistors
2 x 2N3904 transistors
28 gauge wire and some much thicker scrap wire that was lying around (the thicker wire is not necessary)
1 x perf board

Common materials:
1 or 2 Liter bottle
A gatorade bottle
electrical and clear tape
aluminum foil
pill bottle

Soldering iron and solder
Wire stripper (was helpful)
Knife or razor blade
Brain (also helpful)

**LED Info: According to Wikipedia, chlorophyll a & b absorb light at maxima of:
430nm & 662 nm for chlorophyll a
453nm & 642 nm for cholorphyll b
So make sure that you find blue (440490 nm) and red (~625-740 nm) LEDs that are as close to those maxima as possible!
Also, you will notice that there are many more red LEDs than blue ones, this is because I read that red LEDs are more important for flowering than blue LEDs (I was corrected, blue is for growth and red is for flowering) and many people are completely successful with red LEDs alone. Whatever you do, don't waste your money on green LEDs because that wavelength is not absorbed!

Step 2: Assembling the Joule Thief Circuit

So robomaniac does an EXCELLENT job of describing the joule thief circuit. I don't want to steal his thunder so I will suggest you look at his instructable for more detailed instructions, especially since I don't know how to make a real wiring diagram...

Since, I don't know how to do a real wiring diagram this one will have to do. I apologize for all the crossing wires, but it should give you the common person's idea of how it is set up. The wiring colors probably look like I'm hooking up a car stereo with all the purples, blues and yellows but I was just trying to keep people from getting confused when the wires are crossed. The colors are not important, just so you can distinguish between the wires.

Basically we will expand this to have 5 Blue LEDs in one joule thief circuit and 25 Red LEDs in another joule thief circuit. All I can say is make sure your Emitter (E) leg of the transistor goes to the (-) of your battery and LED, the Cathode (C) leg goes to the (+) of your battery (through the ferrite core) and LED, and the Base (B) leg goes to the (+) of the battery (through the ferrite core). Also when looking at the transistor the lettering goes E B C from left to right when you are looking at the side that has the writing on it (so the side that says "2N3904" is the side that has E B C from left to right). Practice with one LED first to make sure it works!

Ultimately, I made two of these circuits for my design

Step 3: The Board

Image 1: So, after you make TWO of those joule thief circuits, we can now make our board. Below is the configuration for my board, there is nothing special about it, I just tried to space the LEDs out across the perf board. All the LEDs labeled blue... are blue, and the rest are red.

Image 2: This will probably be the most helpful to you of any of the 3 pictures here. Again, the colors are not that important, just note the purple is (+) and green is (-). Also, to avoid confusion the blue LED circuit wires are a little lighter than the red LED circuit wires. The wires come off of the board so that you have (+) and (-) wires for your joule thief circuit 1 (red LEDs) and joule thief circuit 2 (blue LEDs). If you look at step 2 again you can see where purple and green wires connected to the (+) and (-) ends of the LED right? Well, since you made two of those joule thief setups with separate ferrite cores, transistors, etc. you will hook up one setup to the (+) and (-) of the red LED circuit and the other to the (+) and (-) of the blue LED circuit as seen in the diagram below. Hopefully, this makes sense.

Image 3: I guess I will show you the back of my board where I wired everything, but really don't pay attention to it because it looks HORRIBLE (yet amazingly it doesn't short if it gets shaken around a little). You will probably learn nothing from this picture except that I should never design major roadways. Make yours better than mine.

Step 4: Battery Holders

So I used 2 kinds of battery holders (to go with the two joule thief circuits) because I wanted to use 3 batteries with the red LEDs and only 1 battery with the blue LEDs. This was because there were many more red LEDS than blue ones and because my red ones were 12000 mcd and the blue ones were only 6000 mcd. Putting them in separate circuits allowed me to dedicate more battery power to the reds.

Image 1: This first image shows how I made a battery terminal using xtank5's design, it's simple and again I will leave you to the original instructable for it.

Image 2: This second battery holder was made out of a pill bottle I found lying around. Basically, a hole in the lid for the (+) wire that connects to a piece of aluminum foil, then batteries (3 in this case) and a piece of foil at the bottom that is connected to the (-) terminal, which is supported by some small pieces of folded cardboard (to make it somewhat "springy").

Step 5: Focus! Daniel-san...

In this step, we are going to focus the light that the LEDs are giving off. To do this, I cut off the top 1 inch of a 1 liter bottle and the square shape of the board made it so that it would just sit on the top, while the LEDs were inside. I taped it down with a little bit of electrical tape. To try to block the light from escaping, I taped aluminum foil to the INSIDE of the sidewalls to reflect the light inward.

Step 6: The Planter

My planter utilized a Gatorade bottle because they make great self watering planters if you cut them just below the indented notch, which is a little above the middle of the bottle. I saw the idea first from whamodyne and will reference the instructable it's from:

I used an old t-shirt that I cut into strips and used them to "wick" the water to my plant. The image below is fairly self explanatory. Since these will one day be lemon TREES, I can't keep them in there forever but for now it has been very useful in keeping my plants watered.

** It is helpful to wrap the container with something like old newspaper so that light is not shining on your water very much, to keep down the growth of algae. **

Step 7: Plant Stuff!

In my example, I am growing lemon, grapefruit and orange trees with my grow light, but you can probably do it to start any kind of plants you like!

I hope you enjoyed this instructable and vote for me in the contests if you liked it!

If you have any comments or questions feel free to leave me a message below!



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    20 Discussions

    You can make a smaller joule thief using 5 mm led a 100 ohm resistor and a coincell battery and tape

    I did something similar to this. I used a trenty Starbucks cup, Velcro coin cell batteries and six 5 mm leds.

    Can I use UV LEDs? I don't know if works with plants! (sorry for my bad english)

    how many batteries do you use because i was thinking of using leds chirstmas lights

    How many windings do you need?
    A 1-5
    B 6-8
    C 9-13
    D 14+

    If you are thinking of building a diy grow light please take note of this.
    Each and every led needs to be atleast 1watt each. Anything below that will be useless so don't use old leds out of toys or old boards, they simply will have too little Total lumens versus lumens per watt. You need atleast 10mm LEDs with 1watt per LED to supply enough light to the plant anything lower will not work. A good combination is a pannel made from 75% 1watt red high brightness leds, 20% 1watt blue high brightness leds and 5% 1watt amber high brightness leds. somewhere in the region of 660nm for red and 460nm for blue
    There is also no effective difference in penetrative power for horticultural purposes between a 1W LED and a 3W LED. So anything over 1watt is just wasted. This means brightness has very little to do with the benefit you will get once you use 1wat leds. Don't confuse this with a pannel made from say 20 LEDs rated a 10watt as to one with 10 LEDs rated at 10watt. As the 20 watt pannel will use the useless 0.5watt leds verses the 10watt pannel that uses 10x10watt 1watt LEDs that are ideal. This has been tested and proven that 1watt single LEDs have great benefit to plants and anything less is just a waste of time and has no benefit at all to plants. The same applies with going brighter than 1watt has no benefit either.
    Hope that may help some of you. Especially if you are growing indoors.
    Also LEDs are more efficient than any other form of grow lighting available.
    The commercially available LED growlights outperform all other growlamps from HID lamps to including high pressure sodium (HPS) and metal halide (MH) lamps.
    So prepare to see other grow lamps become obsolete as LED growlight take over.

    1 reply

    i also notice that you dont have any UV leds.. you might be locking out some chemical process' that are vutal to the plants growth.. just food for thought. nice design though.. props

    i notice that the larger sapling has a bit of leaf curling. i believe that is due to over watering. i see your self watering system and it looks good but i think you need to make your cloth smaller or take one out. it alos could be due to salts building in your soil.

    dose the uses of a transister make the led any brighter....
    or isit just to regulate

    i grow some plant useing red (well sodium buld)
    and my made grew  plants useing blue (metal halide)
    i got very fat leaves
    he got more growth but very spindly leaves
    so nxt time il do blue for growth and red for flowering
    or just use white
    you can use coloured plastic but it absorbs to much light for what its worth
    low cost energy efficient bulbs you can get flood light versions but they cost about x10 more then the standard just use 3 or 4 of thr cheep 1`s
    aparently you need 10 x 11 watt for good growth i think it depends on the size of grow area

    If I wanted to use 85 reds and 15 blues (for a bigger board) how many batteries would I need? Would I need any different parts than what you have listed?

    Am I correct in assuming that there is one each of the resistors and transistors for each sequential string of lights? It is not clear from the diagram or pics but since only two of each were purchaced this would seem to be the case.

    1 reply

    That is correct, sorry it was not clearer. The red LED circuit has its own resistor and transistor while the blue LEDs have their own separate resistor and transistor for their circuit.

    This is pretty cool Ralegg, here in So Cal I use aluminum foil shiny side up laid at the base of my tomato's to get added sun exposure to the vines, I wonder if the same would hold true to give a little extra kick to your grow light? 5

    Once you take the lemon seeds out of the lemon, you could use the lemon to make a battery, https://www.instructables.com/id/Lemon-Battery/
    Then it would be a renewable energy - LED Grow Light using Joule Thief Battery Power in a Wick Gardening Container for CHEAP!

    If you can make it into perpetual energy machine you'll really have something ;-)

    1 reply

    Haha, yes I have thought about what it would be like mixing this with the supercharged lemon Instructable

    Blue is for growing, red is for flowering.. Also remember Wikipedia is not expected anywhere as factual information for research.. I like the idea allot, but wouldn't you need to be checking all the time to make sure your battery hasn't given out.

    1 reply

    Just as a test, the 3 batteries that were hooked up to the 25 red LEDs had already gone through MANY rigorous hours of use in xbox 360 controllers and they lasted for almost a full 48 hours until they started to dim. So if you were to use this with new batteries, I think that you could get a lot more time out of them, I will be testing them with full batteries soon.

    Thanks for clearing that up with the blue for growing and red for flowering.

    Also, I know Wikipedia is not a truly scientific source, but I'm lazy and it's a quick find for things. In the end, if someone completely disregarded the wavelengths I placed on here and just bought "red" and "blue" LEDs they would still probably be quite successful with this project. On a side note, here is a link from the University of Hamburg (Germany) that verifies the wavelengths that I wrote earlier.