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Would it be possible to use a multi-core cable to have power and data in the same wire?

I'm using WS2815 LEDs. The total current needed is 9.6A. For a cable of 8 meters, a 2.5mm wire is needed. Because of the distance between the microcontroller and the first LED I am planning to use a MAX485.

Could I use a four core 2.5mm2 cable to transport the needed power (12V and ground) and data (data A and data B,) or is there a high chance of interference on the data lines because of the 12V at 9,6A (almost 120W) in the same cable.

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  • \$\begingroup\$ Power supply is constant current, so it should not interference with data lines. \$\endgroup\$
    – Piotr
    Apr 30 at 20:09
  • \$\begingroup\$ Using a 2.5mm wire to send data is a waste of copper but no reason it wouldn't work. \$\endgroup\$ Apr 30 at 21:16
  • \$\begingroup\$ If you can possibly feed the power separately it would be good to power the strip from both ends and / or from the middle. Long strips of LEDs tend to be dimmer the further you get from the power injection point. \$\endgroup\$ Apr 30 at 22:06
  • \$\begingroup\$ @Peter also the internal wire traces on the PCB are not rated for 9.6 amps. \$\endgroup\$ May 1 at 2:16
  • \$\begingroup\$ @Piotr it's not constant current it's constant voltage AND the rapid current change of color changing leds means the current isn't steady. \$\endgroup\$
    – Passerby
    May 1 at 2:48

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No, there won't be any crosstalk like that. You can use appropriate wires for each task. So the signal line can be any modest size of data wire, e.g. 0.2 mm2.

The power wires, however, are a whole different kettle of fish. You can't just use "the default" wire size. You actually have to do a voltage drop calculation and not a guess. The quick pass I did on your 9.6A, 8m, 12V wire is that considerably larger than 2.5mm2 will be required to have an acceptable voltage drop. Unless you consider 13% to be acceptable.

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  • \$\begingroup\$ Yes, 10% would be okay. See calculator Would it be considerable smarter to use 24v PSU + 5-meter cables and then a 24v>12v converter for the last 3 meter? \$\endgroup\$
    – Mark
    May 1 at 10:12
  • \$\begingroup\$ @Mark absolutely, that should do it. Doubling voltage halves current giving 1/4 the losses over the same wire. Also think about voltage drop down the LED string. It can help to feed it in multiple places. \$\endgroup\$ May 1 at 17:45

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