Electrical Engineering/Building a LED Light


QUESTION: Hi, so I'm not really sure if I'm asking this question in the right place, if not please direct me to a better location to ask this question.


I don't know a ton about electronics, but I have messed around a fair share with LED lights. Inspired by a youtube video, I have wanted to build a LED light strip for my own aquarium. The video is here: https://www.youtube.com/watch?v=MbMJ5S8MSTs

So I what I want to do is get a six foot long piece of aluminum, and mount about 8 led chips to it. The chips I want to get are 12V and 20W. They can be found to buy here:

Now that i've described what I want to do, here is the question: How would I go about powering these lights. Would it be possible to get one high powered LED driver to supply all the LED chips in a series? Or would each individual light require its own LED driver?

Also, would the simple aluminum plate be enough of a heat sink? Or would I need to get heat sinks for each individual light? Link for the heat sinks i have found: http://www.ebay.com/itm/High-Quality-Aluminum-Sunflower-Heatsink-Radiator-For-20

The reason I want the 20w chips is because it is a very large aquarium, with many live plants. I want the 20w lights to have enough light output to be able to grow the plants.

ANSWER: It is always a better engineering solution to power each light with its own driver and heatsink. However, a common heatsink is just as well if you can properly mount them.  The idea of the heatsink is to attach the sink as close as possible to the source of the heat so it can be carried away and keep the led junction as cool as possible, thereby extending its life.  So, the closer the heatsink to the led and bigger it is the better off is the design.

It is a better way to power each led with its own driver. If you were dealing with low wattage devices you could drive them easily with one driver but with this big of power rating it will be a better solution to keep them separate from each other. This makes it easier to troubleshoot when something goes wrong and provides a simple way of installing without error or malfunction.

So far as light output required for plant growth I have no opinion as that is not an area of my expertise.

Final comment; the lamps you referred to are SMD-LED variety.  SMD or surface mounted devices means they are mounted on a surface and the leads are usually soldered into the mounting area.  I hope that you are equipped to handle that level of sophistication and delicate installation.

Good Luck.

---------- FOLLOW-UP ----------

QUESTION: Great, thanks a lot. Yes, I have a fair amount of soldering experience and I've watched videos about mounting the SMD-LEDs, so hopefully that goes ok.

How about if I considered an alternate design. If I were to get 10 10w LEDs and power them all with a 100w LED driver, would that work? Would it work if I were to mount only 8 of them with that same driver?

Also, if I were to use the 10w LEDs, do you think I could get away with just using the 6ft aluminum plate as a heat sink? Concerning the heat sink, I recognize it probably depends on the aluminum plate I am using, and how well the LEDs are mounted, and the distance between the LEDs- so it may be a difficult question to answer.

Anyways, thanks for the timely response and expertise.

Thanks for the followup question.

I think it would be ok for the 10w LEDs connected up to one driver so long as it has sufficient current capability.  You can check the spec of the LEDs and the driver for current.  The driver must be able to supply the current of one LED times 10, or course. If you use 8 LEDs it would be even safer.

I don't have a clear vision of the layout and location of the mounting for the LEDs on the aluminum bar but from what I can envision it seems safe enough.

You can always check the temperature of the LEDs upon first firing them up to see if they go too high after running for a few minutes or hours.  It is a very practicle thing and much experimenting may be necessary to get the optimum results.  

Good Luck to all.  

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