My Lumia 5.2 / Jarduino Build

[djmx2002]

Would love to see what kind of light placement you are going to do on your 500g system, I got 265 gallon tank which I am trying to decide how to luminate.

[jamesbm1001]

I have a quick question for you regarding LED multi chip arrays such as the lumia. I have been looking at different ways to construct an LED system for a 180 that I'm setting up and would like to do it both as efficiently and inexpensively as possible...two ideas that seem to often be at odds with each other. The lumia looks to be a great option as it provides a significant number of high quality LEDs in a small package. But with all the channels being individually addressable, it requires multiple drivers. if one were to take 24 cree LEDs, and run them in series/parallel 3 parallel 8 LED strings, and where at each -/+ bridge all the led's shared a common rail, would it be possible to avoid voltage and current being shared unequally? That is to say, would the differences in vF be negated?

http://s63.photobucket.com/user/Mort...ebbfd.png.html

[jamesbm1001]

[jamesbm1001]

That didn't quite work how I wanted, but in any case if you can see the picture via the link, the red is positive input, the black is the negative, and the blue bars represent a continuous bridge from positive to negative in each string and from side to side connecting the 3 strings at each junction.

[jedimasterben]

Originally Posted by jamesbm1001

I have a quick question for you regarding LED multi chip arrays such as the lumia. I have been looking at different ways to construct an LED system for a 180 that I'm setting up and would like to do it both as efficiently and inexpensively as possible...two ideas that seem to often be at odds with each other. The lumia looks to be a great option as it provides a significant number of high quality LEDs in a small package. But with all the channels being individually addressable, it requires multiple drivers. if one were to take 24 cree LEDs, and run them in series/parallel 3 parallel 8 LED strings, and where at each -/+ bridge all the led's shared a common rail, would it be possible to avoid voltage and current being shared unequally? That is to say, would the differences in vF be negated?

http://s63.photobucket.com/user/Mort...ebbfd.png.html

The voltage needs to be as exactly equal as possible or current will vary wildly across each string. LDD are less than $7.50 apiece, and even cheaper than that if you can wait more than a week or two lead time, parallel strings just don't make sense anymore.

[Aqualund]

yeah in theory it would still "work," but it wouldn't be anywhere near optimum performance, or achieve any gain aside from just being able to do it., plus there is no protection from thermal runaway on this circuit...so you'd need to add some transistors and load balancing in there to account for it...meaning more loss of energy.

So yeah it would work...but it wouldn't be the best choice.

[jedimasterben]

As long as the LEDs were on the same heatsink, though, the thermal runaway shouldn't be much of an issue, the heat load should be pretty balanced.

[jamesbm1001]

I'm not trying to argue I just want to make sure I understand because in my mind it would work, but sometimes I oversimplify. Were you able to see the image? It's the first time I've attempted to use photo bucket or post a picture so there is definitely no guarantee I did it right. But if you have 3 rows of LEDs and 8 LEDs per string, and the current is applied across the 3 rows, the current would be shared evenly correct? So if the next junction where you would normally bridge only the string from - to +, you connect all of these solder pads together, that is the 3 negative pads from the first LED in each string and the the 3 positive pads of the next LED in the string, you'd be back the the same initial current at the start of the of the second row right? So if any single LED failed, the neighboring LEDs in that row of 3 would split the extra current between them, but the rest of the strings would be unaffected. Also you don't have to worry about balancing the vF of the strings because you're basically making a 3 led parallel connection at each junction, and you just repeat it 8 times. At least that's my theory...now please tell me why it won't work.

[jedimasterben]

Originally Posted by jamesbm1001

I'm not trying to argue I just want to make sure I understand because in my mind it would work, but sometimes I oversimplify. Were you able to see the image? It's the first time I've attempted to use photo bucket or post a picture so there is definitely no guarantee I did it right. But if you have 3 rows of LEDs and 8 LEDs per string, and the current is applied across the 3 rows, the current would be shared evenly correct? So if the next junction where you would normally bridge only the string from - to +, you connect all of these solder pads together, that is the 3 negative pads from the first LED in each string and the the 3 positive pads of the next LED in the string, you'd be back the the same initial current at the start of the of the second row right? So if any single LED failed, the neighboring LEDs in that row of 3 would split the extra current between them, but the rest of the strings would be unaffected. Also you don't have to worry about balancing the vF of the strings because you're basically making a 3 led parallel connection at each junction, and you just repeat it 8 times. At least that's my theory...now please tell me why it won't work.

If the voltage is exactly identical across each string, only then will the current across each be the same. If you're using any different LEDs across each, the voltage will vary and so will current.

If an LED in a string fails, 9/10 they fail open, meaning that current will cease across that string, and the remaining two strings will then share the total current. Voltage isn't divided up among LEDs unless you're using a constant voltage power source (you should be using constant current), the LED driver will automatically adjust the output voltage to match what is necessary for the string to strike, this is another reason the voltage must be identical.

[zachts]

In your three parallel string scenario it will work fine as long as you have some safety in place to allow for one string getting more current than another (and they will, even if all LEDs are the same make model and bin number) the voltage of each LED varries a bit from one to the next so each string will not get the exact same current. This is fine as long as you have a device in place like a current mirror to hold the strings current in check, or if you use three strings of lets say cree xte that can handle 1500mA and you only run the three parrelel strings at a total of 1500mA then each strings will see roughly 500mA but if one strings gets more it won't matter. And further more if two strings fail open it still won't matter. However you would never want to run this set up above 1500mA unless you had some control in place or just didn't care if one string fails and takes the whole arrray with it (not likely but it does happen if you look back at all the very early parallel LED builds on RC).

The down side is you lose out on nearly 2/3 of the potential light this array "could" produce if each string were on it's own 1500mA driver, however it would last just about forever on a good heatsink.

[zachts]

If you want' to run lumias via a paralell array I would strongly suggest current mirrors, I've used them and they are not all that ineffecient or hard to build but only make sense on HUGE builds.

[jedimasterben]

In the days when an LDD is a fuzz over $7 if you want it now, I still don't understand running things in parallel on different drivers

[zachts]

Originally Posted by jedimasterben

In the days when an LDD is a fuzz over $7 if you want it now, I still don't understand running things in parallel on different drivers

imagine a massive array of all royal blues for a very large tank, You could run 8 or more strings of 14-16 royalblues off a single HLG type driver using some very, very simple current mirrors, and it greatly reduces the number of components and space the whole thing takes up. (or more likely a whole bunch of luxeon k16 royal blues.....) But gennerally speaking yes, there are not many applications any more where parrelel still makes a strong case. (I do still use them often though for cheap budget builds where I only wont one cheap arse ELN driver but need 34 plus royal blues or Reds(in the case of freshwater) and only have the space for one driver or the need for the whole driver/PSU assembly to be near water proof as is the ELN driver, for mounting somewhere it's likely to get wet like under a tank near the sump.....

there is also a good place for uber cheap grow out builds.....

[jamesbm1001]

My idea isn't due to a space limitation or a price point limitation. I was looking at the 3 parallel strings for 2 reasons, at 1500mA total current running the XT-E's for efficiency and long life of the LED. My other thought is that by connecting the 3 strings not only at the beginning and the end of each string but at every junction along the length of the strings, if one LED in any string were to fail, the rest of the string would stay on. In theory, the two LEDs at the same row in the other two strings would then share the extra current until I could replace the dead LED. The second idea is where I'm not sure if I'm just out of my mind or not as I don't really know if it would work.

[zachts]

Originally Posted by jamesbm1001

My idea isn't due to a space limitation or a price point limitation. I was looking at the 3 parallel strings for 2 reasons, at 1500mA total current running the XT-E's for efficiency and long life of the LED. My other thought is that by connecting the 3 strings not only at the beginning and the end of each string but at every junction along the length of the strings, if one LED in any string were to fail, the rest of the string would stay on. In theory, the two LEDs at the same row in the other two strings would then share the extra current until I could replace the dead LED. The second idea is where I'm not sure if I'm just out of my mind or not as I don't really know if it would work.

there is no reason your second idea won't work, but it would be impractical for a DIY and is getting way beyond and off the topic of this thread.

[jamesbm1001]

Agreed and apologies, I did not want to get off topic as much as I have

[mkj]

I'm looking to run 3 Lumia 5.2 in a triangle pattern, on a 50Gallon quarter circle. Would the 250w 48v 5.2a PS work for 3 Lumia 5.2? cheers. I also need to run 10 ldd sense 5 ldd will only run 2 Lumia.

[Aqualund]

No, if you use all 700mA drivers you need at minimum 7 Amps to run at full power...so You need something ore along the lines of the 10 Amp PSU to be safe. Buut....you may not need 100% capability.

[jedimasterben]

You'd be right at capacity on the 250w power supply, you'd be using 210w of it, and you always want to leave at least 20% unused wattage of the power supply.

I'd really recommend the Meanwell HLG series though - you could get away with the HLG-240H-48 since they are made like drivers and can be run closer to their capacity.

The LDD drivers, in a nushell, convert excess voltage on the string into drive current, so running two Lumia channels on one LDD uses around 36v - on a 48v power supply, the LDD outputs 45v, so you have 9v leftover that is 'converted' to current, so instead of the LDD pulling the full 700mA rating, it will only pull 560mA (but will still output 700mA to the LEDs. I hope that makes sense the way that I explained it.

[thedru13]

With the 5.2 you need at least 2 1000ma drivers. Not sure you would need 3 5.2s for your set up. Seems like a lot. They are pretty powerful. I run 2 for my 65g tank.

[zachts]

Just throwing this out @mkj
Have you figured the total watts consumed by your three lumia using thier specs at the desired drive current. Using LDD drivers you only need to worry about maximum string volts to size the supply for the highest volt string + 3 volts to be safe. Then figure the total watts and add 20%.

I don't have the time to do the math at the moment but it may work out to be much less than you think......

[zachts]

actually HLG-240H-48 can run AT OR BELOW rated capacity! as they are designed to deliver full voltage and wattage at a specific amp ratting........

[jedimasterben]

Originally Posted by zachts

actually HLG-240H-48 can run AT OR BELOW rated capacity! as they are designed to deliver full voltage and wattage at a specific amp ratting........

#winning



lol

[wilsonreefs]

Aqualund,
You guys are way over my head haha..... I have a 240 gal reef setup that is 8' long x 24" x 25". I am currently using MH's and I want to go to led's. I have 4 2'x2' openings that I could hang a led fixture over. Could you suggest a setup and how to build? I was thinking with the Lumina (I think) could you use a 6" x 6" heat sink or does it need to be bigger. I saw where you used clusters on the outskirts of the main led. I like the Kessil's lights they're just expensive. Any help would be appreciated.

Thanks
Carl

[oreo57]

Originally Posted by jedimasterben

The LDD drivers, in a nushell, convert excess voltage on the string into drive current, so running two Lumia channels on one LDD uses around 36v - on a 48v power supply, the LDD outputs 45v, so you have 9v leftover that is 'converted' to current, so instead of the LDD pulling the full 700mA rating, it will only pull 560mA (but will still output 700mA to the LEDs. I hope that makes sense the way that I explained it.

At first read that made no sense.. but I guess if you consider the LDD will increase or decrease the V to maintain a specific current ,even as resistance in the LED's changes (which it does in a confusing way AFAICT) then I guess it "converts" volts to amps..
current= voltage/resistance
voltage = resistance*current

not sure where you are getting the 560mA from ...
Never too old to learn though...