LED Build for 50 gallon tank.

[HomerJ]

Been playing with SketchUp today.  Here's what I came up with for now.  I'm just about to pull the trigger on 48 Cree LEDs.  Stay tuned.

I modeled the heatsink to this one from Heatsinkusa.com:
http://www.heatsinkusa.com/categories/8.460%22/?sort=priceasc

Mounted on 1" angled aluminum bars.  Cross braces are 1" square aluminum tubing.

[HomerJ]

Leds are in the mail!

24 CREE XP-G R5 Cool White
24 CREE XP-E Royal Blue

Open to suggestions on drivers/power supplies.

I have an Apex, so 0-10V is a must. Let me hear what you think I should go with. Only requirement is to be able to dim blues and whites seperately.

Parts List up-to-date (27 March, 2011)

• 4x Meanwell ELN-60-48D
• 24x CREE XP-E Royal Blue 3W LED on star
• 24x CREE XP-G R5 Cool White 3W LED on star
• 3x 8.46"x12" Heatsinks
• 1x 72" 1" Aluminum angle (cut in two parts).
• 1x 36" 1" Aluminum square bar

[JetJumper]

Leds are in the mail!

24 CREE XP-G R5 Cool White
24 CREE XP-E Royal Blue

Open to suggestions on drivers/power supplies.

I have an Apex, so 0-10V is a must. Let me hear what you think I should go with. Only requirement is to be able to dim blues and whites seperately.

My vote is for meanwells. 

[HomerJ]

My vote is for meanwells. 

That was my initial thought, but I'd need 4.  StevesLeds has some drivers that look like they could handle the bulk with only 2 drivers.  (4 parallel strings of 6 leds times 2).  Of course I'd still need a power supply, but I have access to those for fairly cheap.

[HomerJ]

Mr. Canada Post had some gifts for me yesterday!

My 3 heatsinks arrived from Heatsinkusa.com

I also received my leds ( 24 XP-E Royal Blue and 24 XP-G Cool Whites ) from Rapidleds.com

[HomerJ]

I drilled and tapped the heat sinks so I can mount them on the angle aluminum bars that will hold everything together.  The green tape is just so I don't scratch the aluminum too much.

I will likely start to drill and tap the holes to hold the led stars tonight.  I'm glad I have a drill press for that!  96 holes... yuk!

[NanoSF]

I will likely start to drill and tap the holes to hold the led stars tonight.  I'm glad I have a drill press for that!  96 holes... yuk!

They make thermal adhesive you know. Man I would not have the patience you have. I would just be gluing them on.

[HomerJ]

They make thermal adhesive you know. Man I would not have the patience you have. I would just be gluing them on.

Yes, I know but since I'm not sure about the color ratio so I'd rather keep the option to be able to remove the LEDs if I need to.  Screws will take a while but will be the most flexible in the long run.

[HomerJ]

Phew.... Drilled all the holes, and tapped about 1/2 of them last night.  It's not too bad once you get the hang of it.  And I only managed to break one drill bit, and one tap bit.  :-S

[HomerJ]

Whew! Done drilling and tapping 96 holes! It wasn't as bad as I thought with some music and a (few) beers.

Test fitted a few LEDs. Next step is figuring out the cleanest way to wire them up.

[NanoSF]

Nice thing about aluminum is how soft it is compared to steel. Much easier to work with. Looks great. All you projects are so tidy and impressive. How are you driving these? Do you have the tiny individual drivers or a few bigger ones?

[HomerJ]

Slowly getting there.

I have mounted my LEDs, after putting a small dab of Arctic Silver thermal compound behind each star.  Everything wired and ready to try out!

[NanoSF]

Man it's getting exciting. Fire it up and post to tell us how it went. Are you driving parts of the blue separate from the whites? Will you have control of the lighting cycles? Are one colour on the black wire and the other colour on the red wire?

[HomerJ]

Yes, the whites are on the black wire, and the blues on the red wire (or the other way around, I don't remember!).

I am using 4 Mean Well ELN-60-48D dimmable drivers.  12 LEDs on each.  So theoretically, I should be able to control the 4 sets of 12 separately.  I don't think I need that kind of granularity, AND I only have 2 0-10V channels available on my APEX controller, so I will combine the 2 white drivers into a single control signal, and the 2 blue drivers into a single signal as well.  I can upgrade my apex later if I need more granular control.

I will likely try it out tomorrow, I need to build a cable for my APEX first.

[NanoSF]

Well even if you did have 4 separate controls they would be sided rather than progressively brighter. Might as well just have 2.

Would these LEDs in this configuration have the old Christmas tree lights problem? If one goes dead they all go out and you can't find the dead one? Or does a dead one still pass through the power?

How do you know what driver to use and how many to hook up to it. There are so many Meanwell drivers what is the difference other than some have dimming and some don't?

I see a Meanwell CLG-60-24 for sale in BC on Ebay for example. How would I know how many Cree LEDs to hook up to that, and does that drive even work with those LEDs? I am so electronically useless 

BTW I am not asking you to take the time to tell me the answer to my example, just in general how do I find these answers?

[FocusFin]

Man it's getting exciting. Fire it up and post to tell us how it went.

This is looking great. Very impressive.

[HomerJ]

Well even if you did have 4 separate controls they would be sided rather than progressively brighter. Might as well just have 2.

Having them sided would allow simulating the sun as it passes through the sky during the day, but I have no intention or need of doing that!

Would these LEDs in this configuration have the old Christmas tree lights problem? If one goes dead they all go out and you can't find the dead one? Or does a dead one still pass through the power?

They can fail in either states from what I have read.  If it fails short, it acts as a "passthrough" and everything else will still work.  The driver will have to work harder to maintain the proper amperage, but it shouldn't cause anything to blow up.  If it fails open, then yes, the whole string will go dark.  At which point it would take about 30 seconds with a multimeter to test the string and find the culprit.  Testing leds with a multimeter on "continuity" will actually light them up a bit, so it is really easy to test them for shorts or defects.

You can also wire shorter strings in parallel, but it is riskier to do so (see below why).

How do you know what driver to use and how many to hook up to it. There are so many Meanwell drivers what is the difference other than some have dimming and some don't?

Well first, the disclaimer.  This is based on MY understanding of how things work, from the reading I have done in the past while.  Please correct me if anything I say here is wrong!

It depends on a few things.  How many leds you want to power is the biggest factor.  And at what amperage you will drive them.  Driving them at high amperage will shorten their lives.

LEDs have what is called a forward voltage, which is the voltage drop that will occur as voltage passes through them.  For example, my XP-Es are rated at 1000mA max.  They have a forward voltage of 3.2V at 350mA, and 3.5V at 1000mA.  I am planning on driving them around 750mA, so the forward voltage will be something like 3.4V.  That means to power a string of 12 LEDs at 750mA, I would need 12x 3.4V = 40.8V.  That means I need a 48V driver.  As you can see, I could have gone with 13 leds per strings (as a lot of people do) and still would have remained in the save zone (44.2V), but getting too close to 48V is playing with fire.

As for the types of drivers, for the 48V, there is a non dimmable (self explanatory!) a ELN-60-48D and a ELN-60-48P.  There are 2 ways to dim using different controllers.  Some have 0-10V control, which is just a 0-10V signal, that is equivalent to the % dimming you want.  0V = off, 10V = 100%.  5V = 50%, etc.  This is what the 48D driver supports.  The other method, it called PWM (which stands for, I think, Pulse Width Modulation).  Using this method, the controller uses a 5V signal, but alternates it on and off a varied number of times per second.  This happens so fast that your eyes don't see the leds turn on and off, but that's enough to make them appear dimmer or brighter.

I see a Meanwell CLG-60-24 for sale in BC on Ebay for example. How would I know how many Cree LEDs to hook up to that, and does that drive even work with those LEDs? I am so electronically useless 

That appears to be a 24V driver.  That means you could run 24V / (the forward voltage of your leds) = the number of leds you can drive.  That would be 6 or 7.  It is rated at 2.5A, so you could run 2 strings of leds in parallel, but be aware it is really risky to do that.  In the case one led in one of the strings fails open, double the voltage will now try to go through to the remaining string.  Smoke will happen, and you will lose 6 or 7 leds times 5$ each. :-S

BTW I am not asking you to take the time to tell me the answer to my example, just in general how do I find these answers?

Now you tell me??  :-b

[NanoSF]

Wow thank you for taking all that time to educate. I think I am getting closer to getting it now. There is a few gaps in my understanding still, but I hesitate to ask more as you have spent so much time already. So don't feel obligated to answer, maybe others could chime in and fill my gaps.

My understanding of amps is that they are taken (drawn) by the powered device, not give from the power supply. So is the reason that the LED would over amp itself that they will draw as many amps as they can and get brighter and brighter until they pop?

Next is how do you feed only 750mA? Does the driver allow you to set this? In your formula even at the full 1000mA you would only use 42 of the available 48 volts. How do you not over drive them?

Also if you can set it does this mean in the drive I used in my example I could run only one string of 7 LEDs and tone the driver down from the available 2500mA to 750mA? Wasteful I know, but in theory would it work?

Oh ya BTW have you had it over the tank yet? And you are right about the morning sun rise and evening sunset thing, that might be kinda nice Now that you have decided against it lol. That's whats great about this hobby though. There is always something else you can do in the future.

[HomerJ]

My understanding of amps is that they are taken (drawn) by the powered device, not give from the power supply. So is the reason that the LED would over amp itself that they will draw as many amps as they can and get brighter and brighter until they pop?

You are right, it should have read "double the voltage" not "double the amperage".  Remember these are constant CURRENT drivers.  They will adjust the voltage to keep a stable current.  In the case where one of your led string dies when wired in parallel, the leds will still use up the same amount of amps, but the driver will push double the voltage.

Next is how do you feed only 750mA? Does the driver allow you to set this? In your formula even at the full 1000mA you would only use 42 of the available 48 volts. How do you not over drive them?  Also if you can set it does this mean in the drive I used in my example I could run only one string of 7 LEDs and tone the driver down from the available 2500mA to 750mA? Wasteful I know, but in theory would it work?

On the drivers I am using, there is an adjustment screw.  Rapidled has a nice howto on adjusting the drivers.

http://www.vinnymarini.com/pictures/rapid_docs/Using%20Your%20Dimmable%20Driver.pdf

The idea is that you turn it all the way down, and then with a multimeter inline, you crank it up until the mA are what you want.  I don't know about the driver you are looking at, but the ones I use are adjustable from 24-48 volts. 

Oh ya BTW have you had it over the tank yet?

Nope, I want to avoid having rigging something up "just to try".  That's usually when something goes wrong!

[Hookup]

Nice work and great info I. This thread... Should be stickied

One question...  What are you doing with the third Heatsink?