1800leds project. Am I doing this right?

Hardware
1

Hello!

I’m currently working on a project to add 1800 leds to my ceiling.
The room is a rectangle 4.70m x 4.30m (18m total, so 1728 leds).
I have around 20m of WS2812B strips (96leds/m) available.
Those will be in Paulmann Delta Strip profiles in the corners between the walls and the ceiling
The board I installed WLED to is an AZDelivery ESP32

Now how do I power all this?
My estimated power consumption for worst case scenario (full brightness white) would be
0.30W * 18 * 96 = 518.3W
518.3W / 5V = 103.68A

First thing I thought of was to have 2 60A/300W PSUs and each would power half of the strips.
So I bought a single one to test with 9m first.
Would be 0.30W * 9 * 96 = 259.2W (51.84A)

It did not went well lol. Factory strip wires just melted under power. So I soldered some new thicker wires and it went great! Satisfying moment!
Progressively adding max power limit in the WLED app, I added more and more length of leds.

Now I’m trying to power 5m (480leds, 29.4A) and the white is not white at the end of the strip and the solder I made starts fuming.

How do I fix this? 2 ideas I though of:

  1. Thicker wire
  2. Power injection

I bought 8AWG wire that could handle that much power (iirc) but it’s really thick and I don’t know how I can solder it on the tiny bit of the strip. How could I do that?
Can the strip even handle that much amps?

About power injection, at first I would like to avoid it because I don’t want many wires running around the ceiling so I can keep it clean looking.
Ideally, I would have those 2 60A PSU on the same corner of the room each powering an end of the single 18m strip.
But if I have to do power injection, there’s still a problem (?).
How I would do is 4 PSUs on each corner of the room, each powering 2 halfs of wall.
(2.35m + 2.15m (432leds per PSU))
But the problem is, I have a corner where there’s heating pipes running from floor to ceiling. I don’t know if the power wires would be fine?

TLDR;

  • How can I safely solder an 8AWG wire to a led strip? (Huge difference in thickness)
  • Can a 9m led strip even handle 55A on a single power wire?
  • If not, is it safe to run power wires along heating pipes?
  • If not, what could I do to power a single 18m (1728 leds) strip in a room with only 4 corners to run wires from floor to ceiling?

Thanks for reading!
Hope everything is clear! :slight_smile:

2

First mistake: 5V.
Not that you can’t work with it, but higher voltage needs lower current. My Xmas illusions have 600 WS2812, 12 Volt LEDs. I run power over #16 wire to each end of the strings and it works well on a 10 Amp power supply.

The JST connector is rated at 3A, so trying to pull more than 3 or 4A through them will start melting things. (The copper traces on most LED strips is rated at 4A).

In general, you should provide power every three meters. That is what the extra wires are for:

WS2812B-Addressable-RGB-LED-Strip-5m-300-LEDs-White-IP30-Pigtails

I don’t believe your calculations are correct. Are you REALLY going to run them all white all the time? Even if you do, I haven’t seen a WS2812 strip draw anywhere near 60mA at full-on white. Take a hundred LEDs (you don’t have to cut the strip, just tell WLED that you have 100 LEDs) and use a VOM or DVM and MEASURE the current draw with 100 LEDs on full-white. Multiply by 15 and that’s your power supply rating.

By the way, most switching power supplies can’t be put in parallel for additional current.

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3

That’s generally the right approach for measuring the real power draw of your LEDs, its just your math is off.
Take the measured current of 100 100%White LEDS in Amps and divide by 100, that gets you the maximum current per LED.
Multiply by the number of LEDS in your strip, that gets you the maximum current for your strip in Amps.
Multiply that by the voltage of your power supply in Volts and get the maximum required Watts for your supply.

Best practice would suggest you get a supply 30% bigger than you calculate to allow for power losses in cabling/connections/etc.

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4

In order:

  1. You don’t, you solder a short length of more modest wire to the strip (say 18AWG) and attach that to the 8AWG.
  2. Nope not by itself, the strip is effectively a piece of wire with LEDs hung off it. The gauge of that wire has a voltage drop like any other. You can measure your strip and see what happens in the real world, but reasonable guesses say it will be something like 22AWG.
  3. How hot do the pipes get in worst case? In general it’s probably not a great idea.
  4. You might consider using a number of buck converters to make multiple “in place power supplies”.

The general issue is long distance power injection is problematic with 5V because of voltage drops.
Voltage drop depends on the wire size and the current. If we want smaller voltage drops we either increase the wire size or decrease the current. But how to decrease the current? My LEDs need what they need!

We cheat - use a 12V (or higher) power supply to drive a small buck-converter that will drop the 12V down to 5V. You put the buck converter(s) very close to the injection point(s) along your strip. The converters need to be beefy enough to supply power for their “injection portion” of the strip but they’ll draw power from the 12 bus along your strip.

It comes down to basic math - 300W of power at 5V means 60A, for 12V it’s 25A, for 18V it’s 15A, 24V is 12.5A.
Voltage drop depends on the current through the wire, not the voltage. So the buck converter solution lets you use smaller wires to distribute your power across the strip. Additionally the converters can often be put very close to the injection point minimizing the drop from the converter to the strip.

Definitely do the actual current measurements to see what you’ll need in real life, but consider going to the “mulltiple power supply” solution.

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5

Yes, I was thinking 1500 LEDs. The reason for measuring the power required by a subset of the LEDs rather than just one is because each LED will be slightly different. So measure 18 LEDs * 100.

6

Yah, in general it’s better to measure a bunch and divide by the number measured to get a good average.

I typically do between 10 and 40 and average it out. That will also include the “standby current” of the remaining dark LEDs in the string, although you can measure that by setting everything to 0% brightness and measuring the total current.

7

Ws1215 12v

Start with those… if powee usnt an issue.
Less points of injection.

8

Let’s summarize.
First there are two issues to consider electrically - voltage drop and ampacity. Ampacity is how many amps a conductor can handle without melting itself or anything else; this depends on the cross section of the conductor (thicker is better) and on how thermally insulated it is to build up heat (more is worse). Voltage drop reduces the voltage at the furthest pixels from the source, which may change their color or even fail to operate. This depends on the cross section (thicker is better) and the length (longer is worse).

The strips themselves have an ampacity which others have said is around 4 amps (if directly soldered and not going through a JST connector), before things start going bad (quickly with melting or a fire, or more slowly with degradation due to heat). From that you can calculate that at full white (your nominal 60ma/300mw per pixel figures) you could power about about 66 pixels (60ma * 66 pix = 3960ma). That’s only about 2/3 meters at 96 led/m. That is, every LED should (in this calculation) be within around 66 pixels of a power injection point (one direction or the other). Larger power supply wires do not affect this, it’s just about the ampacity internal to the strip itself.

What can you do? Well, they typically draw a bit less than 60ma at white, which helps a little bit but not dramatically. And perhaps the 4A limit on the flexible PCB’s could be stretched some. But to get major gains, you need something like using WLED to limit the brightness to fit within some amperage (built in function of WLED). If you never averaged over 20ma for each LED, that would allow 3 times as many pixels of reach beyond the power injection.

You can consider 12v strips. The WS2811 variety has 3 LED packages per controlling WS2811 chip - that is, the visible LEDs are controlled in groups of 3 (which are wired in series), thus reducing the current by 3 also. The WS2815 variety has individual LED control at 12V, so that has some advantages, but with some tradeoffs including costs. We haven’t even got to dealing with voltage drop, but 12 strips also have more margin to deal with voltage drop without malfunctioning or discoloring.

Going for less density (eg: 60 leds/m) would also help, whether at 12 or 5v.

And none of this has yet gotten to the power supplies and power supply wires.

What it comes down to is that (1) you will need to do power injection at more than just one point, likely at many (2) you will likely need to limit the average brightness using WLED’s power limiting functions.

You do NOT need huge power supplies or 8 gauge wires (the power supplied would just melt your strips long before those were needed). 50 amps is a real fire hazard, know what you are doing before getting that high a current. (And never connect the + of two power supplies to the same wire, they do not work well in parallel, any difference in voltage/current curves between the power supplies will make them fight each other; if you have to use multiple power supplies, have each power a separate group of LEDs, with only data and ground connecting those groups, not + power).

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9

So what would be a suitable gauge for wires, if I want to run 10m of LED Strips with 60 LED/m? Can I inject to both strips at the connection point with the same additional wires?

10

This depends on how far the power supply is from the strips - how long are the injection wires?
Voltage drops depend on:

  1. Amount of current carried by the wire (we get this by measuring or calculating the max.draw of 1 LED and multiplying by the number we drive with the injection wire)

  2. Length of the wire (we measure or calculate this)

  3. Gauge or size of the wire (normally you’ll use a voltage drop calculator with 1) and 2) to choose a size that’s right)

One footnote to the previous longer discussion by @Zeph:
It’s true that the strips have an “inherent ampacity” - the strip can be though of as a wire itself, around
20-26AWG depending on the manufacturer.

What is often missed is a simple way to double the number of pixels you can drive with each injection wire, don’t inject at the ends of the strip - do it in the middle(s). That way your injection wire supplies current to “2 strips” to the left and right of the injection point.

It does mean you need a wire big enough to handle twice the current of an end-only injection point (or 2 wires of smaller size that add up to the total needed).