First Arduino Project - Need Advice (powering WS2812B LEDs)

Question

I'm making a long LED display made up of 3 (8x32) LED matrices to go inside of a car. I can't seem to find any in-depth guides on this sort of thing. If anybody has examples that they would like to share please do!

The major issue I'm having is power. I'm extremely new to electronics, and I don't understand how these lights can be powered separately, and still be addressably lit by the Arduino?

Parts: 3* LED matrices (8x32)

https://www.amazon.com/gp/product/B088BTXHRG/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

1* Mega 2560

Here's the mock-up schema:

enter image description here

I forgot to draw in a switch, and a power line leading to the Arduino. But let's assume there will be a switch before the resistor and a line that feeds power to the MEGA 2560.

What in this schematic doesn't look or sound right?

Thank you all in advance for your help. This is probably not at all how to go about building circuits, and I'm trying my best to learn. All advice is wanted!

• Dave Newton: In addition to the answer, you might want to read learn.adafruit.com/… and learn.adafruit.com/sipping-power-with-neopixels. It's not shown in your diagram but keep in mind that the Arduino and power supply/ies need to share a ground as well.
• dandavis: you should get 12v LEDs instead of 5.

Answer 1

Powering the LED panels

Powering your panels will be your greatest challenge!

These LED panels are powered by a single +5V power input per panel and do not need a resistor in the power supply path (they actually need a very low resitance path). You do need a good quality +12V DC -> +5V DC power supply (or multiple, as explained below).

Since 3 x 256 RGB LEDs require a large amount of power when they're all lighted at the same time (something like 60mA * 768 =~ 46A), the power supply should be able to accomodate that. It might be better to use three individual, smaller (~15A) power supplies. You could opt for power supplies smaller than 15A, but you should ensure that all LEDs will never light up at full intensity at the same time.

For supplying power from a 12V car battery, you could use high quality 12V DC to 5V DC buck converters (they're efficient). Use good quality cable with a diameter large enough for transporting the large currents necessary. If you need connections in the path of the power supply, make sure they are good quality as well. To reduce losses in long stretches of wire, you should place the buck converter(s) near the LED panels.

Connecting the data lines

The color and intensity of Individual LEDs is controlled via the data input coming from your Arduino and it only needs one input to control all 768 LEDs. The first panel's "data out" should be connected to the next panel's "data in" and so on, like your drawing.

Software

I recommend you look up the FastLED library and some of its examples to get familiar with controlling large amounts of addressable RGB LEDs. There are many good examples and interesting projects out there.

• dandavis: I think it should be mentioned that this whole idea is very impractical for a car, all but impossible w/o great expense and expertise, and would be non-trivial even with mains power available. A cigarette lighter socket for example can only do 15A, and it will quickly overheat at that load. You alternator probably only kicks out about 50A, and your car needs some to run, so you'll likely kill the engine and drain the battery in no time even if you managed to get everything safely wired up. Use LCD displays if you need that many pixels..
• StarCat: @dandavis, I agree, but it is feasible, especially if not using lighter sockets (which are about the worst sockets in the world i.m.o.) but direct, fused connections and not keeping the intensity at maximum. It’s up to the asker.