DIY LEDs - The write-up

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Jay1982,

Those are not fitting how they should.

It is mainly because of your wires.

You can use a dremmel tool and cut a notch for the wires.

Try fitting them on a brand new star with no wires to see how they should fit.
Also the carlco optic holders did not fit perfectly over my XPGs until I opened up the hole for the LED a little with an exacto knife.

Stu
 
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I did a temp and PAR check last night.

Start up temp was 77 degrees measuring against the inside slot of an XPG star. PAR was 113.

After 10 minutes temp was 84 degrees, no PAR change

After 15 minutes temp was 88 degrees PAR was 112

After 30 minutes temp was 94 degrees, no PAR change

After 1 hour temp was 97 Degrees and PAR seemed to stay at 112.

The room temp was in the low 70's with a ceiling fan running above the fixture.
 
Hi peeps, I was curious, how do you figure the amount of leds to use for a specific size tank? I have been bouncing through the forums. Thanks
 
westmoorenerd said:
So, I'm in the planning stages of building my LED fixtures....I'm going to have 8 12" heatsinks with 30 LEDs a piece...After reading through this thread a few times I still haven't quite figured out the best way to power all of them. I'm not quite sure it would be that safe to run the necessary amount of ELN-60-48D I would need to run everything in series, but everything I've read here STRONGLY discourages parallel strings. Any LED gurus want to chime in on my best options? Maybe Meanwell's new LED drivers the HLG series?
Click to expand...

I do not know why people are STRONGLY discourages parallel strings. They are designed to be used with multiple strings of LEDs. They lose much of their efficiency running single strings and the cost jumps way up. I have run two strings of 13 XPGs and 13 XPEs without any resistors and no problems. They are used that way for street lights and if they were not reliable there is no way cities would be adopting them. look at page 14 of this PDF. http://www.meanwell.com/product/images/LED/LED_SF.pdf

I just wish they had a little more info, on why you would want to chose either of the first two parallel strings. The second diagram will be much easier since I am planning to use 5 long strips, each with 2 strings of 30 LEDs. I hope if I balance them I should not need the resistors, saving electricity. I will fuse them as I see a potential plus and no disadvantage to it. This should only require 2 drivers if I use the HLG-120-54B for my 96" 240 gallon tank.
 
laverda -

If you notice on the right hand of the page you are referring to, it is listing "uneven brightness" as a disadvantage of the configuration. Since there is such an incredibly steep increase in how much one string would hog the current with a small change in voltage drop between strings, you really would want to use a variable resistor on each string so that you can dial them in. This way, you don't have one string taking 600 mA and the other taking 400 mA due to very small additive change in voltage drop between strings.
 
widmer said:
laverda -

If you notice on the right hand of the page you are referring to, it is listing "uneven brightness" as a disadvantage of the configuration. Since there is such an incredibly steep increase in how much one string would hog the current with a small change in voltage drop between strings, you really would want to use a variable resistor on each string so that you can dial them in. This way, you don't have one string taking 600 mA and the other taking 400 mA due to very small additive change in voltage drop between strings.
Click to expand...

Yes, I saw that. I thought the purpose of the resistors was to balance out the string and eliminate uneven brightness. I plan to balance the strings as much as possible, to elimanate the need for a resistor. In my testing the Vf is very close at lower currents. As the current increases so does the varation in Vf.
 
Thanks guys for the help regarding the optics. I was wondering if there was a way of getting the optics to stay in place without the optic holders. Cutting the holders and grinding them is taking a long time and they really don't look good
 
widmer said:
laverda -

If you notice on the right hand of the page you are referring to, it is listing "uneven brightness" as a disadvantage of the configuration. Since there is such an incredibly steep increase in how much one string would hog the current with a small change in voltage drop between strings, you really would want to use a variable resistor on each string so that you can dial them in. This way, you don't have one string taking 600 mA and the other taking 400 mA due to very small additive change in voltage drop between strings.
Click to expand...

widmer

I've been running three CREE 48LED fixtures in parallel strings of four without problems with different drivers. I'm under driving them as if one string opens the rest dont fry. My soldering is average and I know the math on LEDs forward voltage and current. I have yet to see a problem. According to some PAR readings this may be a more efficient way to go.

Have you run into any problems with an actual build using parallel strings of 12?

Bill
 
DSCN0143.jpg


these are mine
 
I'll order them tonight. Thanks for the heads up. Do you have to epoxy these ones on too? It looks like they have pegs that snap in the ends of the starboard for the XPGs. Mine look so ugly compared to what you have LOL
 
Jay1982 said:
I'll order them tonight. Thanks for the heads up. Do you have to epoxy these ones on too? It looks like they have pegs that snap in the ends of the starboard for the XPGs. Mine look so ugly compared to what you have LOL
Click to expand...

i used loctite 2 part epoxy. the liquid stuff. not the putty.
 
Thanks, I just placed my order, I'll go pick up the 2 part epoxy. The putty I was using was utter garbage, lol.


lol, I'm pretty pumped right now about these optic holders. I'll post up some pics of my melted optic holders for everyone to laugh at.
 
wld1783-

I have never put any LEDs in parallel. But that's cool if it's working out for you. I think all of this parallel/nonparallel stuff was discussed a few dozen pages back in great deal, but I was tuned out because it didn't and probably might not ever pertain to me unless the prices of the LEDs drop drastically, and even at that point I might not be so interested in doing the work with the multimeter and variable resistors on strings to even out the current. I'd rather squeeze close to as much light out of the LEDs as they will produce.

But you are certainly correct about running more LEDs at lower current being more efficient. If the startup cost doesn't matter so much and you're more about using as little electricity as possible, then that's the way to go.
 
widmer said:
wld1783-

I have never put any LEDs in parallel. But that's cool if it's working out for you. I think all of this parallel/nonparallel stuff was discussed a few dozen pages back in great deal, but I was tuned out because it didn't and probably might not ever pertain to me unless the prices of the LEDs drop drastically, and even at that point I might not be so interested in doing the work with the multimeter and variable resistors on strings to even out the current. I'd rather squeeze close to as much light out of the LEDs as they will produce.

But you are certainly correct about running more LEDs at lower current being more efficient. If the startup cost doesn't matter so much and you're more about using as little electricity as possible, then that's the way to go.
Click to expand...


beat me to it. exactly my point.
 
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