Using the WLED current limiter

Hardware
1

I have a prototype setup with a benchtop power supply for a 5v LED strip SK6812 RBBW and a computer powering an ESP32.

The strip is 300 LEDs long.

The power calculator says I will need 14A.

Setting this up, with a limit of 10A in WLED, the benchtop supply shows 4.7A at 100% brightness (RGB+W), and WLED estimates 10A.

  1. I am somewhat curious as to why the calculator is so far out. I get that all strips differ, however this is double, and I guess WLED uses similar calculation as its estimate is also double.
  2. The outcome, is that to set a real value of say 5A, I need to set the limit to 10A which doesn’t feel very satisfactory or safe, and without the supply display, I won’t know what is really being drawn, and it could be real 10A which might not be good.
  3. The calc says to put 3 power injections, however there is no drop off in colours, the lights will not go any brighter (as the power supply is capped to 10A also, and is drawing ~5A), so would I really need this?
  4. I can imagine I would if I was putting too many amps through the wires of the strip itself, however there appears to be a recommendation to have one injector at 7.3A so I assume the strip wiring can handle this, and therefore a peak possible draw of 5A is fine?

Any advice greatly appreciated
Dave

2

Measure single LED color (R or G or B) current when at full brightness, multiply by 3 then by count of pixels. That’s how WLED calculates.
FYI W channel is not taken into account.

Once you have single pixel current consumption use custom value in LED settings.

3

According to the spec sheet, they are 18w per metre, which is 0.3w per LED, giving 60mA per LED. Multiplying by 300 gives 18A. Or 90w for 5m /5v = 18A

Yet I am only measuring 4.7A at full brightness from benchtop supply.

Is there some impedance on wiring or something that means I should be injecting at both ends to get full brightness?

4

You need beginning, middle and end supply for 5m 5V.