DIY COB LED grow lights

[Yukondave]

About a year ago I bought some COB (chip on board) LEDs to build a grow light. These are 50W, you can't see it in the photo but there is a 5x10 array of 1W LEDs on each unit. After experimenting with them and the Samsung H series LED linear modules I decided the Samsung LEDs would work better for my plant set up. The COB LEDs went into the spare parts bin and I forgot about them. Well recently I found some used T-slot aluminum extrusion and got to thinking about building a light bar that would also function as a heat sink. I haven't been able to find the power supply I originally experimented with so when I find that I can continue. I originally thought about mounting the LED directly to the aluminum but now I'm thinking of attaching them to a plate that is then attached to the extrusion with a bolt and t-nut so I can slide the LEDs back and forth to put the light where it is needed.

 

[Hackerberry]

Looks very interesting. Let us know how it goes. I am fascinated with LED DIYs.

 

[Yukondave]

I got a lot done over the last 2 days. I decided to cut the extrusion in 5 inch pieces and mount 1 LED on each. I drilled and tapped for M5 screws.


The LED vendor claims a beam of 120° so I wasn't sure a reflector was necessary. What I did do was find some pie plates at the dollar store with nice thick bottoms which I hoped would work to dissipate some of the heat.


Here's the power supply that I'm using for testing. It's 50W which means the two 50W LEDs will be putting out half what they are capable of. This also means the heat is divided between the 2 so thermal management is a bit easier. I have 2 more on order from China but don't know when they will arrive. They are $11 each including shipping.


Bench testing the configuration.


Not crazy about the light but they are supposedly correct for growing.


I had a piece of threaded rod laying around so I used that for temporary mounting for testing. I was surprised at how hot the aluminum pieces got, hot to the touch but not too hot to hold onto. The pie plates were not even warm so they don't seem to play a part in dissipating the heat. I haven't decided if I need to add fans yet.

 

[Hackerberry]

Looks good. You will probably need fans if you want to prolong the life of the LEDs. I just buy a heat sink with attached fan from a computer shop.

 

[Yukondave]

I grabbed a couple out of my spare parts bit. It turns out they have M3 screws so I put M3 t-nuts on them and tightened them up and, voila, instant cooling.

 

[Yukondave]

Without the fan running the temperature holds around 48° but with the fan running it holds at 26°.

 

[Yukondave]

Just a quick run down of approximate cost of one 50W LED assembly:

50W 380NM-840NM Full Spectrum High Power LED Chip Grow Light-eBay-$7.20
50W LED Driver Waterproof Power Supply 1500mA-Banggood.com-$10.93
Aluminium Heat Sink Fan For 30W 50W 100W LED Bulb Cooling Cooler 12V-Banggood.com-$9.17

For the fan power I just used a wall transformer I had in my spare parts bin, I have been saving them for years. I also used assorted wire, marrettes, lamp cord and a plug.

So for $30 you can build a grow light with claimed output of 4000 lumens.

I'm starting to see 50W COB LED units that run directly off 120V without the need of a driver priced under $7.00. I think I have my next project figured out.

 

[WillyCKH]

Looking good, Dave!
Great idea using the baking pan, looks really neat. Have you thought of painting the inside of the pan white to further spread the light?
Willy

 

[Yukondave]

Looking good, Dave!
Great idea using the baking pan, looks really neat. Have you thought of painting the inside of the pan white to further spread the light?
Willy

I did Willy, but they are "non stick" pans so they will need a good surface prep before I can try.

 

[Yukondave]

I'm still waiting for the other 2 drivers to arrive from China, after waiting 2 weeks I'm sure glad I paid extra to get them here in 3-5 business days. Anyway, I set them up in the shop at work to try and over winter our pond plants. The lights aren't very bright since I'm running 3x50W LED on 1x50W driver, so for now I won't need any cooling fans

 

[Yukondave]

I just received a part in the mail today, a 70 watt COB LED that runs directly off of 110 VAC. Play time.

 

[WillyCKH]

What kind of cooling option are you going to use?

 

[Lloyd Gordon]

What's the colour temperature?

 

[Yukondave]

What kind of cooling option are you going to use?

Same as the others, mounted on a piece of aluminum extrusion with a fan mounted on it. I have a few 110v muffin fans.

 

[Yukondave]

What's the colour temperature?

The specs say: Color wavelength: 380-840nm

 

[WillyCKH]

It's a purple LED, Lloyd.
70 watts power with a small chip size may need something more than passive cooling... Just saying.

 

[Yukondave]

I got it mounted to a piece of aluminum.


It's so bright it's like looking into the sun.


The temperature climbs rapidly without a fan.


I mounted a fan on it but it's too loud, I'll have to find something that runs at a slower speed.

 

[Yukondave]

I think there are aliens in my basement.

 

[Windowsill Nepenthes]

Or an underground streaptease room...

 

[Hackerberry]

Wow, looks very bright. So you mean to say that it has a built in driver?