Seth's DIY Cree XM-L LED build

[Seth81]

Hello everyone, I've gotten a bunch of questions about my DIY light fixtures. So I thought I should make a new thread about it.
First off my goal is to have an automated dimmable lighting solution with a night mode that is capable of growing coral, with minimum Algae growth (so cool light all the way).
Basically I designed 5 Lighting strips suspended over my tank with aircraft cable hanging from my canopy rails. This way they are mobile and easily removable.

Here is the Basic LED layout:

Components
5 x 24"x4" Wide Heatsinks from Heatsinksusa.com
20 x Cree XM-L T6 Bin 1B cool White LED's mounted on Star PCB from www.cutter.com.au
15 x Cree XP-E Royal blue LED's mounted on Star PCB from www.cutter.com.au
35 x Star PCB shaped thermal pads from Cutter
2 x 100 Watt Thomas Research products LED dimmable driver (2.8 Amps) from www.thomasresearchproducts.com
1 x 40 Watt Thomas Research products LED dimmable driver (700 mA) from www.thomasresearchproducts.com
5 x 12 VDC Computer fans from Ebay
100' #18 AWG hook up cable from Active Electonics
5 x project enclosures from Active Electronics
5 x 8 Way Plastic terminal stripes from Active Electronics

Make sure you get some spare LED's I did have one of the whites burn out on me after 30 minutes.

Design Data
Here is just some numbers if anyone is interested:



I tried out the fixtures with no fans at all...and after a few hours they got too warm to hold, not burning hot or anything, but too much to be constantly touching, so I decided I needed the fans after all. With one fan per fixture the heat sinks stay room temperature.


Driver Specs:

According to the LED spec sheet, at 2.8Amps the forward voltage is 3.35 Vdc, so the voltage range is the limiting factor to the number of LED's I can connect per driver. The model below would be good for 8 - 12 white LED's at 2.8 Amps



The driver is dimmable via a 0 - 10 Vdc signal. I plan to connect this up to my PLC (programmable logic controller) and make a whole sunrise/sunset routine.

I decided against optics at this point . The LED's naturally have a very wide angle light distribution, almost too wide over 120 degrees. The only reason I may use optics is that my tank is 38" tall, and if I find that the light penetration isn't that good i.e. not enough light at the very bottom of the tank, then I will spend the $6/ fixture I was quoted. But when I turned the fixtures on I seriously doubt I'll have a problem.
I promise to add some more pictures soon...i.e when I am not at work