Need to power about 600 LEDs @ 5V which could consume about 30mA each. Looking for power supply options?

Thread Starter

jamesr219

Joined Dec 20, 2012
14
I am working on some artwork that will have about 600 LEDs on it which each can consume about 30mA. (18A @ 5V). I am looking for a power supply solution to power all of these LEDs. My thought is to use a 24V or 36V power supply and buck that down to 5V for each strand of 100 LEDs (~3A @ 5V)?

Any suggestions on the modules I can use to accomplish this?
 

dl324

Joined Mar 30, 2015
11,488
You don't mention the color, so we can't tell if you can connect them as strings of 2 which would reduce current requirement by 50%. If you multiplex them, you don't need 18A; you could drive one at a time. Is the 30mA a maximum rating?
 

ronsimpson

Joined Oct 7, 2019
910
What is the part number for the LEDs? We want to know the voltage.
Is each LED addressable. Will there be a case where only one LED is on?
 

Thread Starter

jamesr219

Joined Dec 20, 2012
14
They are WS2811 RGB LEDS. You clock data into them and they repeat on to the next one.

For some context: here are how they are used: https://www.aeroluxmaps.com

also, that current consumption is for all on white. Rarely if ever would it be in that condition, but still want to design for it in case it should happen.

thanks for your help!

-jr
 

ronsimpson

Joined Oct 7, 2019
910
They are WS2811
Ok. so we can not series two LEDs and run at a higher voltage. (post #2)
That current causes problems. Three amps is smaller wire. Last time I did a LED advertising sign we broke up the panel into small pieces. I do not remember but maybe 8x10 LEDs. Think about what PCB size works, how many LED in a group, and think about 1A or 3A or what little buck power supplies you can get.

I put 1000 of LEDs in a box along with a power supply and computer board. Things got very hot. In your case, 100 watts in a small era.
 

Thread Starter

jamesr219

Joined Dec 20, 2012
14
The LEDs are small 5050 style with wire between them. They are already obtained and used in smaller maps. This one is just large enough I cannot use our normal 5V 5A power supply to power the entire thing and am therefore looking for other better options.
 

Janis59

Joined Aug 21, 2017
1,221
The most energy efficient will be small Chinese pwm regulator individual to each LED or at least short-series (ca three to five pieces in serie). Such cost at ebay anout quarter of dollar a piece.

The most simplest but not energoeffective will be individual resistor to each LED, all parallel, and one Chinese 5 USD pwm 220 to 5V invertor for 20-25 Amps.

The not very trustful but energoeffective and cheap will be straight feed from 220V, via Graetz and Capac. filter with ballast resistor. Say, 220*sqrt(2)/1.7=180 pieces in serie. Let stop on the 150 pieces and four series in parallel. Then V(R)=314-150*1.7=314-255=59 V and resistor must stay R=59/30mA=2 kOhm or better 2.2k. Then N(R)=59*30mA=1800 mW=2 W. The only negative grin is if one LED is defective then all the serie is dark vs other methhods when only minor part of LEDs is dark.

Important: please check the average voltage on each LED in datasheet or if havent then measure before apply this resistor value and recalc if needed.

PS: I have much experimented to substitute that resistor with capacitive or inductive ballast but results are plainly woeful. All burned off fast (at switching on after some tens or hundreds times of successful switching)
 

Thread Starter

jamesr219

Joined Dec 20, 2012
14
I am not interested in running line voltage up to the actual artwork. I’m looking to keep it all low voltage for safety. So after power supply it’ll just be 24 or maybe 36V and then some type of module to buck that down to the 5V needed for each 100 leds which consume about 3A.

so, I need suggestions on a dc to Dc module to accomplish this. For efficiency reasons I’m thinking some type of switching regulator?

thanks again for everyone’s help.
 

ElectricSpidey

Joined Dec 2, 2017
1,235
Why do you feel the need to start with a higher voltage and “buck it down”? Are you worried about line losses?

You can probably use a 5 volt 20 amp supply with a little output adjustment, or perhaps a sense line.
 

Thread Starter

jamesr219

Joined Dec 20, 2012
14
The main reason I was thinking was to be able to use smaller wire and the availability of the power supplies at the various voltages.
 

ElectricSpidey

Joined Dec 2, 2017
1,235
Consider using a surplus ATX supply, and running a heavy gauge wire to a distribution block, then use smaller wire to the individual strips.

Perhaps you could show a diagram of your proposed system?
 
I once helped on the power supply and power distribution issues for a LED array.
Like Ron mentioned, we broke it down in a modular arrays.

The power architecture was as follows, A 240VAC to 48VDC commercial power supply, as the main distribution bus was 48VDC.
Each array had its own point of load regulator from 48 to 3.3VDC.
There was an additional 48 to 5VDC POL regulator for the main computer.
In Digikey they are about US$11 each, but you can find them in Ebay or Alibaba for a pair of bucks.

The enclosure really got warm and required fans, which initially were 48VDC. However their inrush current created bus glitches, and eventually we used 240VAC fans controlled by a solid state relay.
 

Thread Starter

jamesr219

Joined Dec 20, 2012
14
Yes, those are similar to the LEDs we are using. I'm looking for a bit more polished of a solution than a repurposed ATX power supply.

I could not find a desktop/wall-based 20Amp 5V output. Even then I would need 12AWG up to the map and need to distribute it from there. Wouldn't a higher voltage make this distribution easier at the cost of some loss/efficiency during the conversion?

I'm not 100% opposed to using an ATX power supply, but then I need to deal with getting it to turn on. I would want to do a fully modular one so I could only have the one wire I need up to the map. I couldn't find specs to show just how many amps they will do on the 5V bus?
 

BobTPH

Joined Jun 5, 2013
2,538
The max current on a ws2812 is 20mA per color, or 60 mA per chip. But, unless they are to be outside, they would be blindingly bright at that level. I have used these a lot, and I rarely go over 100 on each color.

Bob
 

Thread Starter

jamesr219

Joined Dec 20, 2012
14
That was my original thought as per the sheet, but under actual test with a strand of 100 at 100% white I am getting 2.7amps at 5V.

-jr
 

Dodgydave

Joined Jun 22, 2012
9,426
Yes, those are similar to the LEDs we are using. I'm looking for a bit more polished of a solution than a repurposed ATX power supply.

I could not find a desktop/wall-based 20Amp 5V output. Even then I would need 12AWG up to the map and need to distribute it from there. Wouldn't a higher voltage make this distribution easier at the cost of some loss/efficiency during the conversion?

I'm not 100% opposed to using an ATX power supply, but then I need to deal with getting it to turn on. I would want to do a fully modular one so I could only have the one wire I need up to the map. I couldn't find specs to show just how many amps they will do on the 5V bus?
You're going to be pushed to find a 5V supply at 20A without a metal case and fan cooled, as said each led takes 60mA so 100 LEDs is 6Amps, so so why need 20A .?
 

Thread Starter

jamesr219

Joined Dec 20, 2012
14
You're going to be pushed to find a 5V supply at 20A without a metal case and fan cooled, as said each led takes 60mA so 100 LEDs is 6Amps, so so why need 20A .?
It’s 600 leds. I was just talking about breaking them up and powering 100 at a time with buck down?
 
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