View Full Version : Help with DIY LED unit[60, 3-5W LEDs]

07/29/2017, 06:18 AM
I am in a fix atm.

Ive ordered the following LEDs for my 37G tank:

20x CREE XPG 450nm (max 1500mA)

10x CREE XPE 6500k (max 700mA)

10x Epistar 10000k-20000k (700mA)

10x Epistar 410-420nm UV (700mA)

10x Epistar 440-460nm (700mA)

I know this is a bit overkill, but I figured I could use any extra LEDs to light up other tanks. However, I cannot seem to decide on the optimum number of LEDs I need. I wish to grow corals with Medium light demand, but ones which are considered easy, since this is my first reef tank.

How would you compose your ideal reef led unit? If I max out all the LEDs then it comes to about 450W. And Ive ordered 60 degree optics as well. I know 450W is a humongous overkill, so I am looking for it to be around the 150W range.

I am planning for two channels of 7A each. Channel one will have 10x Cree RB at 700mA each. Channel two will have 5 each of Blue, UV, 6500k and 10000k, running at 350mA each. I'll use two SMPS with 12v 10A power each, and a DIY arduino dimmer, on each channel, to get it down to 7A or if need comes drive them with a bit more current. The DIY arduino dimmer is basically two heat sinked mosfets controlled with PWM. So, I can drive the RB CREEs at 1000mA, and the rest at 500mA MAX.

Is this combination good? Ive got a lot of LEDs so I can go really big too, I am using basically just half of what Im ordering. But I want to keep the power bills low, and I think if the color combination is right then 14A of LED lights is good enough to grow most of the things I can get my hands on.

What do you say?

07/29/2017, 06:38 AM
Oh where to start...
What drivers are you using to limit current to the LEDs?

No offense but you really need to go back and learn the basics of series strings and how LEDs work and need to be powered and the calculations associated with that first..

Learn how currents are calculated in series strings.. (hint.. they don't add)

50-75W is plenty for a 37G tank..

07/29/2017, 08:22 AM
10x Cree RB at 700mA each.

Lets just go w/ an example..
3.05 is the approx V(f) of one rb xpg @ 700mA

Ten in series requires a power supply of at least 30.5V and 1A (30W ps)

Your wattage would be 3.05 x 0.7x 10 = 21.35 W
for that string...

Channel two will have 5 each of Blue, UV, 6500k and 10000k, running at 350mA

guessitmating on the v(f) here to average 3.5V, but this is a rough number..

20 x 3.5 x 0.350 =24.5W

Need 70V DC to light it at .350mA

Using Meanwell LDD drivers and 12V power supplies gives you about 9V per string.
Lucky to drive more than 4 diodes per series string..

sooo using this you may need to do a bit more research............