Build Your Own 3120 Lumen LED Grow Light

I started this journey after after testing several of the low cost grow lights being imported from China. Every one I tested was over hyped, low powered junk. By the time I got tired of fooling with the Chinese junk 3 watt LEDs had come out and I realized that with the right cooling a lot of these could be mounted in a very small space. You can read more about this project on our www.grow-sun.com web site.

Fast foreword 2 years and industry has finally released more affordable LED replacements for screw-in type light bulbs, including LED flood lights. And while in LOWES looking at LED light bulbs one day I wondered if my Grow Sun grow light had been out flanked by technology? I wondered of a lower cost LED based grow light could be put together out of production LED lights? Well, the answer is yes, you can put together your own high intensity LED grow light, and this article shows you how.

We decided to sell a fully assembled version of this grow light fixture. You can find more details HERE.

I did a lot of shopping around the big box stores and picked out a LED flood light I liked. It's a SYLVANIA ULTRA LED flood light. The output is rated at 520 lumens at only 8 watts of power and because of the relative small size (2.5" across) I thought I could get 6 mounted to the housing I had in mind.

The housing I had in mind is manufactured by LMB HEEGER in California. It measures 7" X 5" X 2" and I was pretty sure I could mount 6 LED flood lights in the box.

The sockets I chose are the ceramic snap-in style & they are designed to mount in the same size hole you would punch in a box to mount 1" conduit. The hole is 1-1/8" diameter.

I used MS Word to layout a quick drill template. You can use paint, another drawing program, or hand draw something. regardless you need a template to make the project look sharp at the end.

Any time I'm going to drill a hole in metal I start with a pilot hole. A pilot hole acts as a guide to larger drill bits and you end up with a much sharper project at the end.

I drilled the holes for the power cord, power switch, and grounding point. Because this is a metal box it's extremely important that you use a 3 wire power cord and properly bond the green safety ground to the box.

Then I drilled the main mounting holes. See how stright they are? It's because I used a template then I started the large holes with pilot holes!

Once I completed the holes I mounted the light sockets and did a trial fit with the lights.

Hint: Because the aluminum chassis is flexible it's impossible to push the sockets in from the front. You have to put the socket in the hole, place the chassis on a table top face-down, then use a largish screwdriver to push the chassis into the socket.

Because this is a light fixture you are supposed to wire with high temperature wire. I used Teflon coated 22 gauge wire. Why so small? Because the entire fixture is only going to draw 48 Watts & that's only 0.4 Amps at 120 VAC. 22 gauge wire is rated at 5 Amps.

Connect the internal wiring to the power switch. I used a 2 pole, 2 throw switch because that's what I had. If you use only a single pole switch make sure it's wired to turn the black wire on & off.

Attach the power cord ground to the chassis. I used a 3/16" aluminum rivet and a backup washer.

Whe connecting power make sure the power cord black wire is routed through the power switch and then on-to the brass colored screws on the back of the light sockets.

Close the housing and test.

The lights on picture was taking under normal office light. Also, note that the lights run cool enough for me to hold them. Try that with a Sodium Vapor Lamp!!!

But does this fixture produce enough light?
For comparison, a typical 2 tube 24" florescent grow light fixture produces about 1300 lumens of light.
This fixture produces 3120 lumens of light and you can fit three of these fixtures in the same space that a 24" flouescent fixture fits in.
In other words, with three of these fixtures you can produce 9360 lumens of light - about 7 times more light than two 24" florescent tubes, and in the same space!
I think this fixture produces enough light!

What about red and blue spectrum light?
At these light levels who cares?

Thanks, Tom Hargrave
www.kegkits.com

In a rush to get this instructable published I completely forgot about mounting, so I ran down to Home Depot and bought these mending plates for less than $3.00.

Then I marked the locating holes, drilled the holes, riveted in the mending plates in place, and now I have corner brackets that I can use to hang the fixture with chains and S hooks.

I can also attach the fixture to the bottom of a shelf with screws. Looks like I need to build two more....

After reading some of the great feedback, I went shopping for some alternate bulbs. I found some 1190 Lumen 6500K "daylight" CFL bulbs at Wal-Mart that were not too expensive.

One complaint I have about these lights is they are not a spot light design and the light will transmit from the sides, so in theory if the fixture is above your plants in a open room your plants will not receive as much light from these as they would from a more focused source like a spot light. But if you are going to grow plants in a closed box like I did in this instructable it probably does not matter.

My second complaint is they draw considerably more power - 6 of these will draw 120 Watts where six of the others will only draw 48 watts.

And here is what the lights look like on and off in my fixture.

I did a side by side comparison by first mixing three and three. You can see that my camera "sees" some color difference but not much, probably because the sensor is swamped with light.

Then I re-arranged the bulbs - I put thee of one type down one side of my fixture and three of the other type in the other side of my fixture. I separated the two sides with a heavy piece of cardboard and turned the light on in a darkened room. You'll notice the color difference right away - that's the difference between a 3000K and a 6500K light source. But you'll also notice that the brightness appears about the same even though the LED light is rated at about half the lumens. This is because the LED bulb is a spot light design and all of the light is pointed down. The CFL bulb is a non-spot design and the light is spreading everywhere.

We decided to sell a fully assembled version of this grow light fixture. You can find more details HERE.

Thanks, Tom
www.kegkits.com
www.stir-plate.com
www.grow-sun.com
www.towercooler.com