Controlling multiple 100W RGB leds

Hi everybody.

First things first: I'm a complete noob in wireing things. Coding is the thing I'm good in.

My first project
...was controlling a RGB LED strip.

Works very good.

  • Power suply: 12V 6A DC adapter
  • 12V 5M 300 ledstrip
  • 3x 220 Ohm resistors
  • 3x MOSFET IRLB821

But now I want to make something useful
An LED controller for my fish tank lights. The 12v ledstrips are not bright enough. So I searched the internet and found 100 Watt RGB LED Chips. When I use 3 RGB and 3 Cool White chips I have 36.900 lumen (I dont need that much but I dont want to have them on full power all the time, this way I can use it on 50%).

But here is the problem
The strips I used were 12V and the Arduino could handle that. So I was powering the Arduino and the led strip from the same power source. And I was not afraid about wiring things wrong.

These 100W led chips work from 22-34V and 3-3.5 Amps
I have serious no clue how I should wire this up and be able to control it with an Arduino.

The requirements:

  • 3 RGB 100W 3A led
  • 3 white 100W 3.5A led
  • Controll them with 1 arduino

Note: I dont need to controll the leds each apart. Only the rgb and whites need to be controlled apart from each other.

Can someone help me by telling me how I should wire this up?

And second:
What power supply do I need?

Always a bad idea buying stuff from a website with spelling errors and inconsistency in the technical description they say 100W in some places and 1W in others.

Driving such high powered LEDs is not easy. For each one you need a constant current supply but a 3.5 Amp constant current supply is not easy to build. I would look for a matching controller for these lamps. This is not a beginners project.

We get lots of aquarium projects here so google what they have done and how other people have got on.

Well that page is just an indication. There are tons of shops offering 100W leds.

The reason why I'm asking is this:
I found this tutorial about a mad guy building an insane 1000 watt light grid with 16 of these leds to grow his weed (serious) :smiley: :smiley:

The tutorial exists out of 2 parts: Part 1 Part 2

I thought, I could build the same with this tutorial. Its well written and I understand it. However I don't need 16 leds, I just need 6 and I want to run them on 50% of their power.

This guy uses 4x 24V 15A power supplies and controls the curent with these "buck boosters".

Now al the weed guys there are building the same rig to grow their little plants. So I thought it maybe isn't to hard to do (I dont need 16 leds, just 6).
The only difference is that I want to use RGB leds and control them with an arduino. Doest the controlling part makes it so much different or are there other things?

Reading your "mad guy" tutorial, what he's doing is using a 1 ohm resistor for some level of current control (horrible) and carefully tweaking the buck/boost drivers to a voltage that underdrives the LEDs to prevent them from burning out. So, putting that another way, it's not difficult to run these 100W LEDs in an inefficient or error-prone manner.

But back to your project, I can't imagine you'd want 600W of light sitting over your aquarium. Cut that down 100-fold to 6W and that still seems like a lot of light for an aquarium.

I wonder what happens to the fish if they look at a 100W LED? If I did that I think I'd go blind.

Haha :stuck_out_tongue_closed_eyes:

Well dont underestimate the amount of light a fish tank needs.
In theory a fish tank needs about 20+ lumen per liter for led light (40+ tl)

The fish tank is 700 liter so that is 14.000 lumen. So, 600W is offcourse overkill but I was planning to use them at 50%.
I tried a 12V 1.8A (21W) and the light was realy terrible.

Now im on the hunt for good (cheap and easy) led setup. And I cant figure it out.

Ok. Forget everything above.
I've created a new plan ;D
After reading a couple of hours about leds and powering them. I came with a new solution.

1x Arduino
40x 3W RGB LED
40x 3W White led
30x 36V pwm led driver
1x 350W, 36V Power Supply

It is 80x 3W LED. Total 240W.
What do you guys think about this?

Why is the voltage so high on the power supply? Note that if you want to drive RGB LEDs in series you need the ones with separate LEDs not common anode or cathode types.

Yes, that sounds like a better style of plan and what I would have recommended. With respect to the while LEDs, your LED drivers are 700ma while the LEDs are 300ma (no good). I'd suggest you look for white LEDs that take 700ma rather than a 300ma driver.

Don't forget there are "warm" (yellowish) and "cool" (bluish) types of white LEDs. It might mention that on the page (I can't read it!) but just be sure you're getting the one you want.

Grumpy_Mike:
Why is the voltage so high on the power supply? Note that if you want to drive RGB LEDs in series you need the ones with separate LEDs not common anode or cathode types.

I would think he'd want a high voltage supply so he can put more LEDs in series (fewer drivers/wires). Also, he did select an RGB LED with separate anode and cathode pins for each of the segments.

Thanks for helping me out and point me to the right direction. I never trust a grass smoking weed grower anymore.

@Grumpy_mike: Chargin is right. My thoughts are: how higher the voltage, the more LEDs I can put in series, the less drivers, wires and costs. As far as I know are the RGB leds just 3 leds build into 1 chip. So yes, I thought I could use them this way.

I still have some questions about this:

  1. Is there a limit to this?
  2. Can I go even higher in voltage (I did see 54V 4A supplies)?
  3. And does that make things more dangerous (Electrocuting myself for example :P)?

@Chargin: I did indeed see that there are a lot of colors available. On the white strips I would like to mix things a little. Cold white + Warm white. I've to find some information about what are the best colors but first I want to get my setup right.

Thanks for pointing me out about the 300mah leds. I think this are better ones: LED 700mA/3W?

The questions that remain in my head:
4. Say I've build this and I find out that it isn't enough light. I can increase it to 100x 3W LEDs with this PSU right? (100x 3W = 300W, PSU = 350W)
5. I'm planning to make this a modular setup. So I create aluminium bars with 8 LEDs and 1 driver. Then you can wire them together till you have enough of light. So for example: A 31 gallons fish tank can use 4 bars and a 180 gallons tank can use like 10 or 12 bars. Are there any problems with this way of thinking?

  1. This is how I'm planing to use them. How do I calculate the heatsink I need? I can't find anything about how much heat they generate. The most ideal way would be to cool them passively.
  2. Looking at the image above, the blue area is already waterproof right (they wont be in the water but hanging above)? The red part isn't. Can I use high temperature resistent kit to make it waterproof (like this one (sorry its dutch) which can handle 250 °C/ 480 F)?

Looking at the image above, the blue area is already waterproof right

No, you solder to it so it can't be waterproof. Look up "conformal coating" for making this splash resistant.

1+2) The LED drivers have an upper limit, typically 40V. I can't read the chip on the LED driver you linked but similar drivers show an XLSemi XL4001E1 which lists a recommended 40V or absolute max 45V.

  1. Electrical code in the USA says 50VDC is where you risk electrocuting yourself.

  2. I can only guess but I think the aluminum strip alone would be OK.

Thanks guys, you really help me out.
I didn't know about the coating Grumpy mike. Looks nice and cheap!

So the plan is ready. I will try to build 2 prototypes of these rgb led light modules.

This is a drawing of two led modules.

I will try to build them in these aluminium led frames using 2x 3pin waterproof connectors.

This is the idea of a modulair led light which can be connected in series.
(forget the connector in the image. Its not rated for the 37V so I found other one)

I will place an order next week. Thanks for helping me!

For this solution it is good option to use 6+6T800 POWER SHIELD. It can handle 800W and have up to 6 channels. Please see this product on http://v-vTech.com or buy directly trought ebay.