LDD Drivers, why and how?

cosmith71 · Post by **cosmith71** » Mon Jun 30, 2014 1:39 pm

So who is using/going to use the Meanwell LDD drivers? Why did you choose them over the standard drivers, and what are you doing with them?

--Colin

Rodasphoto · Post by **Rodasphoto** » Tue Jul 01, 2014 7:33 am

I choose them because they have a greater resolution when it comes to dimming. I built a radion clone using them.

cosmith71 · Post by **cosmith71** » Wed Jul 02, 2014 6:59 am

I wonder if it would be worth swapping them in on a regular RapidLED (Cree) setup?

What kind of wiring do you guys use between drivers and fixtures? I've been using speaker wire but that's getting cumbersome with the number of strings I'm thinking about.

--Colin

Rodasphoto · Post by **Rodasphoto** » Wed Jul 02, 2014 11:52 am

You could use multi strand low voltage wire.

cosmith71 · Post by **cosmith71** » Thu Jul 03, 2014 9:01 am

I emailed RapidLED as well to see what kind of wire they'd recommend.

I also asked about how many LDD drivers could go on their Mean Well SE-350-48 power supply. They said up to about 100 LED's (350W) and however many drivers I needed to run them. I was surprised at that answer. That makes them really economical compared to the regular ELN drivers.

Of course, if I do this, I'd need to buy an expansion module and a PWM dimming module. Might as well convert my Jaebo pumps to RA control as well. And swap out my cool white LED's for warm and neutral, add some of those lime green LED's, etc etc. Not so economical anymore.

--Colin

rimai · Post by **rimai** » Thu Jul 03, 2014 9:03 am

cosmith71 wrote:Not so economical anymore.

--Colin

LMAO

cosmith71 · Post by **cosmith71** » Fri Jul 04, 2014 7:01 am

Do these use the 10v PWM or the 5v PWM expansion?

--Colin

blert · Post by **blert** » Fri Jul 04, 2014 7:53 am

You are going to run into no end of troubles if you don't start reading the data sheets for the hardware you choose and doing some research into basic electrical knowledge but I will try and help you out a bit...

cosmith71 wrote:Do these use the 10v PWM or the 5v PWM expansion?

--Colin

LDD drivers are 5v PWM.

cosmith71 wrote:I emailed RapidLED as well to see what kind of wire they'd recommend.

I also asked about how many LDD drivers could go on their Mean Well SE-350-48 power supply. They said up to about 100 LED's (350W) and however many drivers I needed to run them. I was surprised at that answer. That makes them really economical compared to the regular ELN drivers.

Of course, if I do this, I'd need to buy an expansion module and a PWM dimming module. Might as well convert my Jaebo pumps to RA control as well. And swap out my cool white LED's for warm and neutral, add some of those lime green LED's, etc etc. Not so economical anymore.

--Colin

Sounds like Rapid gave you a pretty crappy answer to your question (not typically like them).
That power supply is a 7.3amp model. That means you can connect as many LDD drivers that add up to about 7amps (7x1000ma, 5x1000ma + 4x500ma, etc...) while saving the left over .3amp for wiggle room and driver consumption. It supplies 48v... The LDD drivers consume about 4v, so supplying the 48v will leave you with about 44v for the LEDs on each driver. At 1000ma a CREE XP-G has a forward voltage of 3.15v. This means that you can run 13 XP-Gs off one LDD at 1000ma (44v/3.15=13.9). So, using that power supply and 7x1000ma LDD drivers with 13 LEDs per driver you would max out at 91 LEDs.
That is a very basic explanation and I hope it helps you. Read that data sheets and gather the max amperage and forward voltages of the LEDs you will be using. Do the math and and you should be fine.
For wire choice you need to consider the length of the run and how much current will be through it. Then choose a safe gauge wire to handle it and give you the least voltage drop.

cosmith71 · Post by **cosmith71** » Fri Jul 04, 2014 8:29 am

Thanks for the reply.

I do have basic electrical knowledge, but hadn't dug into specifics yet. I'm still trying to decide if I want to bother with the changeover from the ELN drivers or not. Nothing is set in stone.

So, will a LDD-1000 driver pull 1000 mA regardless of the number of LED's connected to it? I know that generally current is pulled on-demand, but LED circuits and their variable voltage needs confuse me a bit.

--Colin

blert · Post by **blert** » Fri Jul 04, 2014 8:47 am

cosmith71 wrote:Thanks for the reply.

I do have basic electrical knowledge, but hadn't dug into specifics yet. I'm still trying to decide if I want to bother with the changeover from the ELN drivers or not. Nothing is set in stone.

So, will a LDD-1000 driver pull 1000 mA regardless of the number of LED's connected to it? I know that generally current is pulled on-demand, but LED circuits and their variable voltage needs confuse me a bit.

--Colin

Yes, LDD drivers are constant current drivers just like the ones you are currently using, they vary the voltage. It's not too confusing, just add up the forward voltage of each LED and that will give you the voltage demand of your string, or the max LEDs per string for a given input voltage (don't forget the 4v needed by the driver). So, in short, it doesn't matter if you have 1 or 13 LEDs on an LDD, it will always supply the given amperage while varying the voltage.

cosmith71 · Post by **cosmith71** » Fri Jul 04, 2014 9:02 am

Right, the LDD-1000 will supply 1000 mA regardless, but the current it pulls from the 48V power supply will differ depending on how many LED's are on the driver, since the voltage is always fixed from the power supply, correct?

So, we would not be limited to 7 LDD-1000's as long as they are not fully loaded up to the 44V limit, right?

--Colin

blert · Post by **blert** » Fri Jul 04, 2014 9:31 am

cosmith71 wrote:Right, the LDD-1000 will supply 1000 mA regardless, but the current it pulls from the 48V power supply will differ depending on how many LED's are on the driver, since the voltage is always fixed from the power supply, correct?

So, we would not be limited to 7 LDD-1000's as long as they are not fully loaded up to the 44V limit, right?

--Colin

No. LDDs will always supply the given amperage. 7x1000ma LDDs would still max out a 7amp power supply regardless of the number of LEDs, be it 1 LED per string or 13. You can increase the number of drivers if you know that one driver will always be off while another is on. So, you could connect 14x1000ma drivers if 7 of them will always be off while the other 7 are on.

cosmith71 · Post by **cosmith71** » Fri Jul 04, 2014 9:45 am

Where does the extra power go? 48v *1000 mA = 48 Watts consumed. But say we're only using 1 LED at 3.15v. That's 3.15v * 1000 mA = 3.15 Watts output for the LED. 40 Watts of heat?

--Colin

blert · Post by **blert** » Fri Jul 04, 2014 10:37 am

Well, I can't claim to know how the inner workings of the drivers work but, though they do get warm, it's not 40watts worth of heat. Think of it in terms of the drivers you are currently using... You could think of them as a "normal" power supply with 1 LDD connected. Your "normal" power supply will supply a consistent voltage at a varying current allowing you to connect one or many voltage appropriate devices so long as you do not exceed the max current supply. The connected LDD then takes over and supplies a consistent current at a varying voltage allowing you to connect one or many current appropriate devices so long as you do not exceed the max voltage.

ReEfnWrX · Post by **ReEfnWrX** » Sat Jul 05, 2014 6:41 am

blert wrote:For wire choice you need to consider the length of the run and how much current will be through it. Then choose a safe gauge wire to handle it and give you the least voltage drop.

Didn't realize this was important. How can we determine the right gauge wire?

blert · Post by **blert** » Sat Jul 05, 2014 1:44 pm

ReEfnWrX wrote:
blert wrote:For wire choice you need to consider the length of the run and how much current will be through it. Then choose a safe gauge wire to handle it and give you the least voltage drop.
Didn't realize this was important. How can we determine the right gauge wire?

Very important. For one, you don't want to risk a fire. Run too much current through a given gauge wire and things will heat up fast. For two, the longer the run the more the voltage will drop at the end. Not a big deal at higher voltages in most applications but with the low voltages you are dealing with an LED fixture the loss of a seemingly measly 3% can make a huge difference.
Here is the chart I usually refer to when choosing a wire gauge for a project...
http://www.powerstream.com/Wire_Size.htm
Here is the voltage drop calculator I usually refer to...
http://www.calculator.net/voltage-drop-calculator.html

ReEfnWrX · Post by **ReEfnWrX** » Sat Jul 05, 2014 1:53 pm

What is the difference between Maximum amps for chassis wiring and Maximum amps for power transmission?

Which should we reference for wiring our LEDs?

blert · Post by **blert** » Sat Jul 05, 2014 3:05 pm

ReEfnWrX wrote:What is the difference between Maximum amps for chassis wiring and Maximum amps for power transmission?

Which should we reference for wiring our LEDs?

Its in the article. None of this is written in stone and the numbers are all quite conservative but when it comes to a fire in my house I tend to err or the side of caution. I go by the numbers for power transmission in small easily overheated confined projects.

cosmith71 · Post by **cosmith71** » Mon Jul 07, 2014 7:58 am

Got some confirmation.

The current draw by the LDD's from the PS will vary depending on the number of LED's attached to the LDD. Total wattage drawn from the PS is what counts.

So, a half loaded LDD-1000 will only draw about ~450 mA from the power supply and will supply 1000 mA to the LED's at whatever voltage it takes to run them.

--Colin

blert · Post by **blert** » Mon Jul 07, 2014 8:25 am

cosmith71 wrote:Got some confirmation.

The current draw by the LDD's from the PS will vary depending on the number of LED's attached to the LDD. Total wattage drawn from the PS is what counts.

So, a half loaded LDD-1000 will only draw about ~450 mA from the power supply and will supply 1000 mA to the LED's at whatever voltage it takes to run them.

--Colin

That is interesting indeed. Where did the confirmation come from? I may need to reread the data sheets and contact MeanWell on this.

cosmith71 · Post by **cosmith71** » Mon Jul 07, 2014 8:54 am

A thread on Reef Central, which backs up what RapidLED said. Specifically, a posting from someone who had pretty much the same conversation with LEDGroupBuy.com.

Again, basic Ohm's law. Wattage in = Wattage out. Voltage from the power supply is constant, current from the LDD is constant, but voltage varies depending on the number of LED's connected. Therefore, the only other variable is the current from the power supply.

LDD's are DC to DC convertors. Constant voltage in, constant current out.

--Colin

cosmith71 · Post by **cosmith71** » Tue Jul 08, 2014 5:21 am

Looking at these boards from Coralux.

http://coralux.net/?wpsc-product=ldd-5-driver-board

Seems like a lot less hassle than ordering custom boards like the ones in the RC thread.

--Colin

lnevo · Post by **lnevo** » Tue Jul 08, 2014 6:28 am

One of the led companies (rapid or ledgroupbuy) has a daisy chainable board that is pretty cool. One board gets the power supply input and dimmer rj-45 input (i think) and then you can add boards with drivers. You can set what channel number each driver board uses. They also had a board that you can plug fans into.

lnevo · Post by **lnevo** » Tue Jul 08, 2014 6:37 am

Damn, i cant find it now

89delta · Post by **89delta** » Tue Jul 08, 2014 3:53 pm

Before I got my RA+ I was using a DIY controller from BubbasGuppies. It's 6-channels total and selectable per each driver. The Controller itself offered weather patterns,lighting and moon phases via long/lat. But after figuring out the coding for the RA I just currently use the standard pwm channels for my blues and whites. I have 8x 10,000k whites, 4x 420nm UV and 12x 450nm RB's on my heatsink over my 29BC. But I have no issues running these LDD-L drivers what-so-ever with the 10k resistor grounded on one side and the other on the PWM signal side.

cosmith71 · Post by **cosmith71** » Tue Jul 15, 2014 10:09 am

I'm starting to think about wiring.

I have two fixtures, each with 4 channels (8 wires). That's 16 wires coming up from the stand to the canopy. I'd like to have each fixture able to disconnect in the canopy as well as a disconnect before the canopy to simplify removing the canopy.

So,

Code: Select all

                                -----8 Wires-----Plug-----Fixture
                                |
Drivers ------16 Wires------Plug-----8 Wires-----Plug-----Fixture

Would D-SUB connectors work? Maybe a 25 pin and 2 15 pins (for future expandability)? I'm not sure how they're rated.

Right now I'm using Molex connectors, which I really don't like.

--Colin

rimai · Post by **rimai** » Tue Jul 15, 2014 10:11 am

Where are your drivers located? In the stand or canopy?

cosmith71 · Post by **cosmith71** » Tue Jul 15, 2014 10:14 am

Drivers are in the stand.

cosmith71 · Post by **cosmith71** » Tue Jul 15, 2014 10:16 am

I suppose it would involve much less wire to have them in the canopy, although I worry about moisture damage.

rimai · Post by **rimai** » Tue Jul 15, 2014 10:17 am

I think you need heavier gauge than the D-sub cable can provide.
Remember that you could be running up to 1000mA through those wires.

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