DIY LEDs - The write-up

[onetrickpony]

Just wondering, The buckpucks can only run 6 LEDs with a forward voltage of 3.5v or 21volts
any thoughts on running 7 of the XPGs with a forward voltage of 3.0 = 21 volts

 

[TheFishMan65]

It should work from what I have read and understand. But I do not know of anyone that has tried it.

 

[kcress]

Remember the BPs need 2V(?) for themselves. Otherwise it just depends on the total Vf of your string. You could have a bunch of low Vfs and it would allow another LED.

 

[widmer]

Just wondering, The buckpucks can only run 6 LEDs with a forward voltage of 3.5v or 21volts
any thoughts on running 7 of the XPGs with a forward voltage of 3.0 = 21 volts

Sorry, not recommended unless you want to stay in that 350 mA or below range. Here, I clipped the pertinent chart from it's data sheet:

As you can see, even if you go up to ~500 mA, you approach 22 volts which is uncomfortably close to the very max Vf you should have your string of LEDs going. And of course @ 700 mA, you're at 22.5 volts, which is too much. Not to mention the natural variation in binning, under which blind probability gives you a 50% chance of exceeding this Vf as well.

The good news is that the XM series LEDs can easily allow you to drive those 7 LEDs at the Buck Puck's max current of 1,000 mA with plenty of elbow room. See the pic I grabbed from the XM data sheet:

Seriously though, presuming that reasonably-priced optics for the XM series are released soon, I'll be buying them for my next build. At cutter.com.au's website, they're currently $7.something each if you buy more than 10.

 

[MosMike]

Seriously though, presuming that reasonably-priced optics for the XM series are released soon.

I didn't check that specifically, but I have a feeling that Cree MC-E optics can be used with XM-L.

 

[der_wille_zur_macht]

Not sure about that. The MC-E is physically much larger.

That said, it's worth stating that you can pretty much at least TRY to use any optic on any LED. The worst that'll happen is you'll get a lot of spill out the sides if you're using an optic designed for a small (physically and angle-wise) LED on a larger one, and/or you'll get different widths. But even still, you can often correct these problems by raising or lowering the optic with respect to the LED. Not something you'd want to do on a billion LEDs for a big tank, but for experimentation or smaller tanks it's pretty achievable. Heck, right now, I have an XP-G running under an optic that was made for a 3-up Rebel.

 

[TheFishMan65]

Thanks for doing the number Widmer. I was remembering the 3V point as being much higher.

 

[spamreefnew]

does anybody here run without optics? How do i know if/or what angle optics to buy once my light is done and hanging above my 23" deep tank? will it be dark on the bottom? or will there simply be to much light shining on my walls?

 

[der_wille_zur_macht]

There are no hard and fast rules, though optic use is strongly linked to:

1) Desired intensity distribution in the tank. If you want high light at the top and very low light at the bottom, no optics (or wider ones).
2) Desired height above the tank, and depth of the tank. If your fixture is 3' above the tank, you had darned well better have optics. If it's 6" up and your tank isn't very deep, you probably don't want/need them.

 

[TheFishMan65]

spam, tanks size LED count and spacing?

It won't be dark, but may not support the life you want down there.

 

[widmer]

Just noticed your post:

1. Why do you think LEDs are better than metal halide? My impression is that MH emit a huge amount of power as UV which is essentially useless (and actively dangerous), and that they don't dim well. However, otherwise they are more efficient than an LED and are cheaper. One that seems particularly odd to me is that I keep hearing that *20,000K* MH bulbs are too blue! At 20,000K, it should be putting out the majority of it's radiation at 140nm, way, way past the visible range and far into the range where it's extremely dangerous to look at or even shine on your body!

A couple points here:

1. You're totally correct about halides creating dangerous UV radiation. However, the glass shields this from actually exiting the bulb.

2. LEDs are far more efficient than halides at this point. While the best of the bunch halides may approach 100 lumens/watt efficacy in their first couple months of use, the common XP-G LED can do 120 lumens/watt no problem, and the new XM-L can do 160 lumens/watt.

2. How much can you get 10,000 lumen commercial LED fixtures for? I am absolutely confident that I can make an extremely nice one that I would happily sell for under $1500, likely less if I am making more than one or two. Thus, it's sort of a waste of my time to make my own if I can point my friends to one that is just as good and costs less!

I can't comment on commercial fixtures (they cost too much for me to give them the time of day :lol, but for your 10,000 lumens:

14x Cree XM-L from cutter.com.au: $95
2x Meanwell ELN 60-24 to drive them at 2.5 amps: $70
Miscellaneous schwag: $30

Total cost $200 for 10,000-11,000 lumens

This is all white light though, if you're looking to make an aquarium fixture it would cost maybe a little more, but then you don't want to describe it in terms of lumens, as lumen count is a very poor way of referring to intensity of the deep blue light.

3. What are good sizes for me to design for? I could make a 2' long, 5-6" wide fixture that puts out 10,000 lumens, or a 4' long that puts out 20,000 lumens, and so on. But I'd like to design them to be as close as possible to what a general aquarium user might actually want.

This is starting to feel very commercial :lol:; you're going to want to stay underground with your commercial notions or you'll be censored here.

4. ...

 

[spamreefnew]

once i get my fixture built i will post a pic here and we can decide on optics

 

[mseepman]

So although I'm waiting for my house to get built to really get going on my tank build thread, I've been preparing to put together a DIY LED fixture for my 84"L x 32"W x 25"H peninsula tank. I've ordered the necessary LED's on a group buy with my local reef club from ETG and was wondering if you could provide some input.

I will be doing a parallel build using two or three HLG meanwells. Haven't quite put my finger on which ones yet. I will be following all the directions on here about using resistors and fuses and measuring the voltage to balance the strings.

Here's a pic of my initial plan for the fixture. Sorry for the simple drawing but still working on my sketch-up skills and couldn't get it right on there.

Those are eight 4.25" x 10" heatsinks from Heatsink USA. On them you will see XP-E Royal Blue's in dark blue, XP-E Blues in light blue, XP-G CW in white and XP-G NW in light yellow. All LED's but the Blue's will have 60 degree lenses on them. I wasn't planning to put lenses on the blues with the hopes that their coloration will blend over more area without lenses. The surrounding structure will be made of EZtube. The center bar you see is U-Channel and the LED's on it are XR-E Royal blues that I will power with an LPC-700 that I already have with the intent of using them only for moonlights.

This whole structure will be hung inside a canopy structure so it won't be visible. I don't have any limits on how high the fixture can go so I would like some suggestions on how high it should be hung.

Do you think this setup will give me adequate coverage for a dominant SPS reef tank?

 

[TheFishMan65]

I would think so. From what I am reading that is near the equivalence of 2000 watts of MH.

 

[MosMike]

Do you think this setup will give me adequate coverage for a dominant SPS reef tank?

I think that you should spread the LEDs over the tank, do not cluster them. Otherwise you will have darker areas in the tank.

Also, why using neutral whites ?

 

[mseepman]

I think that you should spread the LEDs over the tank, do not cluster them. Otherwise you will have darker areas in the tank.

Also, why using neutral whites ?

Well after reading this entire thread and various threads over at least 6 forums that I belong to, I found a common theme was that coloration was the biggest struggle with the traditional CW/RB mix. Although many found it fine, just as many complained that it lacked something. The addition of NW's and/or Blues seems to have solved some of those individuals issues and so I've included them in my build.

As for spreading the LED's...are you suggesting that going parallel to the tank instead of perpendicular would be a better way to spread the light? I have considered going with 4 x 36" heat sinks each having 48 lights but that would increase my costs a little bit so I had to get some opinions on this first.

 

[Sampo]

Hey guys,please please give me some input

I posted above about a package diy kit " http://www.rapidled.com/servlet/the-58/36-Ultra-Premium-LED/Detail "

My tank is a custom built 32x20x20, im keeping a mixed reef but definitely will have a lot of sps.

So im really interested on what optics i should go with? thinking the fixture will be at 10" above the water level or a little higher

What other equipment i should have other than a heat sink and railing would i need? they have a 24" pre tapped one on the same site

Any other input would be great!!

 

[wfournier]

I think that you should spread the LEDs over the tank, do not cluster them. Otherwise you will have darker areas in the tank.

Also, why using neutral whites ?

Both of those items are pretty much standard practice...

 

[MosMike]

As for spreading the LED's...are you suggesting that going parallel to the tank instead of perpendicular would be a better way to spread the light?

Absolutely right. Also, please specify the current you will feed to the LEDs. I think that after checking the thermal resistance of the heatsinks you could pick a lighter (=cheaper) heatsink.

 

[mseepman]

I like the idea of "cheaper" haha but haven't got many options for heatsinks in Canada.

I plan to run the XP-E's at around 700-800 mA and the XP-G's at 1000 mA. Both should be well within their operating range...especially if I have an issue with the parallel setup.

Here's an updated picture with the LED's running the opposite way. If I stick with heatsink USA...this got even more expensive (especially shipping it to me)

Thoughts?

What about the moonlights...are these too powerful (even if I use only 5 XR-E's over a 7' tank?)