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Discussion Starter · #1 ·
The more I study this, the less I seem to understand.

First, the good news: I've finally got the python scripting working properly for the lat/long network time based sunrise/sunset triggers of <<your south american location of choice>>. I've allowed for a time-shifting function to your local timezone, (say sunrise in French Guyana happens at 2:00am in my West Coast location, and I'd rather be awake to witness the moment, so in my case, it's a timedelta shift of 5 hours). Adding the moon cycle to the same python script -- at this point -- is trivial, so that's next.
All of this is happening on a Raspberry Pi, and then tripping GPIO signals over to an Arduino, which is connected to a 16 channel 12 bit PWM controller.
Eventually I'll skip the GPIO trigger and go with straight up Serial over TX/RX, but I don't have the proper level shifter at the moment to transverse the 3.3v<->5v comm channel, so it's GPIO for now.

That PWM controller, in turn is connected to the MeanWell LDD-1000h drivers.

The system is properly running in test mode right now with just a single LDD-1000 and a simple 3mm LED on a breadboard (currently a 20 minute dim cycle for sunrise/sunset, I may tweak that after some more research)...

This is where I'm stumped. Programming, I get.
Electronics and power consumption, not so much.

I'm wanting to emulate basically the same thing as the Lumia 5.2 (CREE Lumia 5.2 105W Planted Tank LED 5 Channel - Planted Tank Version - LEDGroupBuy.com, but there's no fun in just buying it, I want to build it myself.
Thing is, I can't for the life of me figure out what power supply I'm going to need in terms of voltage.

The details of the LEDs being used on the Lumia, from what I can tell, are as follows:

Channel 1 – 3 Hyper Violet (430nm) and 2 Cree XT-E Royal Blue (18v @ 700mA)
Channel 2 – Cree XT-E Royal Blue (16.5V @ 1500mA)
Channel 3 – 3 Cree XT-E Netural White and 2 Cree XT-E Warm White (16.5V @ 1500mA)
Channel 4 – 2 Turquoise and 3 Cree XP-E2 Blue (17.2V @ 700mA)
Channel 5 – 3 Hyper Violet (430nm) and 2 Cree XT-E Royal Blue (18v @ 700mA)

When you add up all that voltage, you get 86.2 volts. ?? Yet it seems that most people are using a 48v power supply.

Even if you go as simple as just saying "Ok, I want to have 5 LEDs on a single channel off one LDD-1000h, they're all Cree XM-L2 which run (at max output of the LDD) 2.9v and 2.9w @1000mA, (which I doubt I'll actually be hitting that often, except for during brief stints of 'lightning mode').
If I simply add up the voltages of that one channel, I get 15v. If I have 5 channels with the same LEDs (off of 5 LDD-1000h), that equals 75v in total.

Do these power supplies handle 48v over each one of their connections?
250w 48v 5.2A DC Power Supply - LEDGroupBuy.com

I totally don't get it.

The last question I have on the same topic, is if I only have a single LED connected to the LDD-1000h, and that driver is powered off the 48v power supply, how the heck does a little 2.9v LED handle that extra voltage?
I certainly couldn't plug my Raspberry Pi into a 24v power adapter for example. Not without a whole bunch of magic smoke.

Any help here is very very much appreciated.
 

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You are providing the 48v to a current regulated driver of some sort. The LDD-1000h will drive one channel on up to 2 Luminas. What I did was use one 48 volt 325 watt power supply to drive five of the LDDs. Each LDD is matched to the Max current that the Luminas take. Channel one would be a LDD-700, channel 2 would be on a LDD-1000 (wish they had LDD-1500s) and so on. Each LDD drive one of 5 channels. The total voltage drop of each channel cannot exceed the max voltage output of your drive minus ~5 volts to give you some headroom.

Note that the Lumina you mention above is the reef version. They have two different plant versions.
Also the XM-Ls will take much more than 1000mA. I think they can go to 3,000 or maybe higher. If using the Ldd-1000, I would go with XT-Es since they are cheaper and can take 1500 mA.
“Do these power supplies handle 48v over each one of their connections? 250w 48v 5.2A DC Power Supply - LEDGroupBuy.com”
Yes, but again you can’t exceed 250W or for that matter, I would be far more conservative. I have had bad luck with the LEDGroupbuy 500W power supplies. Had three in a row fail in <1 month. I now use these: http://www.amazon.com/gp/product/B00L1GZIHW/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1
The last question I have on the same topic, is if I only have a single LED connected to the LDD-1000h, and that driver is powered off the 48v power supply, how the heck does a little 2.9v LED handle that extra voltage?

Quite simply, the LED will only “ask” for 2.9v. However, it will take whatever current you give it. Give a 1000 ma LED 5,000 mA and you get a pop and total darkness.

Hope that helps,

Bob
 

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Discussion Starter · #6 ·
Great news! I also contacted the seller of the unit I was looking at: 250w 48v 5.2A DC Power Supply - LEDGroupBuy.com

Asked the same question, and they got back to me same day with the following:
That power supply feeds every connection on that unit supply 48v, in parallel.
On that power supply, there's 3 (V+) and 3 (V-)... So ..
I THINK that means I can supply the following setup:
string 1: 5 x 3v LED = 15v
string 2: 5 x 3v LED = 15v
string 3: 5 x 3v LED = 15v
string 4: 5 x 3v LED = 15v
string 5: 5 x 3v LED = 15v total: 75v

from the power supply:
+/- 1: string 1,2 and 3 = 45v
+/- 2: string 4 and 5 = 30v
 

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LEDGroupBuy has great customer service! They get back to you quickly and solve your issues.

I’m not sure you have the power supply exactly right. The power supply will not safely power the LEDs by itself, you need an LED driver for each string to regulate current to your LEDs.
That power supply should be able drive many more LEDs. If you are running 5 strings on 5 LDD-1000 drivers with the drivers powered in parallel, the total voltage drop is 15v for all 5 drivers + 5 strings of 5 3v LEDs. If they were in series, then you have a 75v voltage drop.

That power supply should be able to power 5 LDD-1000s in parallel. Each of the 5 drivers should be able (in theory) to drive one string of 16 3v LEDS in series. However, I would not go over 14 or maybe 13 LEDs on each string.

You just need to be sure of a couple of things:
1. Be sure what your LED forward voltage drop is at the current you are driving them at. Usually the higher the current, the higher the voltage drop. Link to Cree XT-E datasheet: http://www.cree.com/~/media/Files/C...d Modules/XLamp/Data and Binning/XLampXTE.pdf See page 8 for graph.
2. Be sure your total watts for your LEDS (combined) is far less than the maximum rated output of the power supply. If you ran 5 drivers with 12 X 3v LEDS each at 1000mA, that is 3v X 12 LEDs X 5 strings X 1A = 180w. A 250w power supply should be fine.

Hope that makes sense,
Bob
 

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Discussion Starter · #8 ·
I’m not sure you have the power supply exactly right. The power supply will not safely power the LEDs by itself, you need an LED driver for each string to regulate current to your LEDs.
Thanks Bob, makes sense, and yes, I will have the LDD-1000h drivers as the middle man between the 'strings' and the power supply. I think that's what you mean
 

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Discussion Starter · #11 ·
Thanks! My wish is granted. I didn't think of looking at Mouser.

Bob
Sorry to be the bearer of bad news, but the guys from LEDGroupBuy specifically mentioned the fact that the LDD1500 series doesn't work with what we want to do. Something to do with the power rating....

to Quote: "Keep in mind that those do not have the same electrical characteristics of the LDD-H series and are limited to 36v input and 32v output, so you cannot use them alongside LDD-H on a 48v power supply. If you limit to 36v, then you can use them."
 

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Discussion Starter · #12 ·
Will all your LEDs take 1000 mA?
as a maximum, yes, (actually they're rated to 3000mA) I'll play around with it a bit, I'm not even sure I need to go with the grande packages of the XM-L2 series. They're probably overkill.

I'm going to get a couple of them and see how they look at 700mA...
 

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I don't think it's overkill at all. At least you have the ability to increase current and upgrade in the future if the need arises. I have so many old, lower power, low efficiency LEDs that I just don't want to use. It's just not worth wiring up 10 of them when I can buy 1 XL-M2 to do the same job using a lot less electricity and a lot less heat.

Bob
 

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Discussion Starter · #14 ·
Good point. (forest for the trees) I wasn't even thinking about efficiency when I thought they were overkill.

I'm pretty sure I've got the power sussed out now, confident that the 48v will do the trick.
Now the HARD part: The proper number/type/colour of LEDs for the 36x18 top.
I've seen the reef guys using a formula of LxW/22 (which in my case would give me 29 in total) but it's been said here that that is way too many for a planted tank.
 

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Good point. (forest for the trees) I wasn't even thinking about efficiency when I thought they were overkill.

I'm pretty sure I've got the power sussed out now, confident that the 48v will do the trick.
Now the HARD part: The proper number/type/colour of LEDs for the 36x18 top.
I've seen the reef guys using a formula of LxW/22 (which in my case would give me 29 in total) but it's been said here that that is way too many for a planted tank.
My tank is a 65g at 36" X 18" footprint and 24" high. I am planning to use about half the LEDs (about 24 XP-Gs and XT-Es) of what I have used over the same area of my reef tank (72" X 18" footprint and 24" high). I have about 100 XT-Es over the reef tank, which houses mostly "high light" corals. I think 24 LEDs may be a bit much, but I can alway dim the LEDs until I'm happy with the plant health and color.

As far as LED color, I plan to use a mix of cool, neutral and warm whites. I have a bunch from my last reef LED build. I'll mix and match to get the best color and PAR. I'll also put the different colors on different dimmable drivers so I can make adjustments on the fly.

I will also use around 4-8 of these 3-color, 3-ups that I used on my reef tank. They will fill in the missing colors from the middle of the white's spectrum along with some deep red. Link: Ocean Coral White - LEDGroupBuy.com. They really made a difference on the reef tank. Blues, greens and reds were more vibrant.

Bob
 

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Discussion Starter · #16 ·
FWIW, I'm finally getting down to the nitty gritty, and after a bunch of pencil scrawling on scrap paper I finally got to the point of putting together this little sketch pad.
Thought it may be useful to anybody else planning on using the MakersLed heatsink.
It's helped me with my planning, so ... View attachment ledsketch.pdf

I set it up for printing on regular 8.5 x 11, but ledger is nice too.
 

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Finally:)

You'll like those heatsinks. I've built about a dozen fixtures based on them. I had planned to build one from scratch for the new 65 g dart tank. But instead, I went the cheap/easy route and just converted a pair I took off my reef tank. Only had to swap our a few LED colors.

Keep us posted and shout out if you run into problems or have questions.

Bob
 

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Discussion Starter · #19 ·
it's been a ridiculously long time, but I just pulled the trigger on the order. I've generally not been much of a Black Friday sort of person, but LEDgroupbuy have a 15% off sale going on, and this order came to almost $500.
Yay, that means I'll be able to continue on with my build journal.
 
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