I have the following board which powers my Ws2812b and Arduino. As you see in the drawing I marked an injection point after 2.5 meters and connected 5V to this point coming directly from the powersource, 2.5 meters / 8 feet away.
Is it strictly required or suggested that I also connect the GND pin from this power source into the injection point? The GND of the power boards are connected. The gnd is carried from the beginning of the strip and I just cut out and connect 5V at the injection point.
These boards provide 5v 2A output. Can I combine their outputs and just feed 5V 4A combined power into my strip at the beginning of it, rather than creating the injection point? Is this strictly advised against, or is it possible that its a precaution which I can avoid? Can this be harmful for these boards? 5v seems to have a bit of a drop after 2.5 meters
Connect both poles of the power supply at the injection point. That you ask this makes me think that you think the current flows from the positive pole of the power supply into the LED strips then disappears somewhere. It has to get back to the power supply negative pole, ideally through a path of low resistance. I suggest you also connect the power supply to the far end of the strip.
Like many people you are confusing ground with negative. Ground is a point in the circuit designated by the circuit designer and is generally synonymous with 0V, which is the point against which voltages in the circuit are measured against, unless stated otherwise. Circuit ground might also be connected to earth, the muddy stuff outside, usually for safety reasons. The output of a power supply or battery does not have a ground connection, it has a positive and negative pole.
Unfortunately the far end is too far, so its best if i connect it halfway and on.
The GND of the led strip is connected, not cut, from one end of the strip to the other end.
The 5V of the strip is cut halfway. Thats where I plug 5V from one of the charge boards.
So since the ground is there, and the strip seems to be working okay as such, I feel there doesn't seem to be a reason to cut GND of the strip halfway as well, and wire - of the board to this connection on the strip.
I'm not suggesting you cut the ground strip, you must not do so because if you do there will be no return path for the data signal as it enters the second strip. The power supply to the LEDs involves considerable current, the metal strips that carry the current on LED strips are quite thin, so you need to be careful how much current you expect them to carry. For this reason connect both positive and negative to the second strip at the same place, with the negative, also designated ground, connected between the strips.
