Background: I plan to use Pro Micro to drive a LED strip which contain 81 LED. I plan to use one DC adapter to drive both the Pro Mico and the light strip.
I made some math. If I use WS2812b(5V strip), the maximum current required to supply the LED strip is 4.9A (0.06A x 81). If I use WS2815(12V strip), the maximum current required to supply the LED strip is 2.1A(0.025A x 81). The most connectors I can find online have current rating of 2~3A per pin. Thus I tend to chosse WS2815. For wire, I plan to use 22AWG.
Please make suggestions on my plan. My main concerns include:
1) LED strip type selection
2) Power supply mode
3) Wire gauge selection
4) Connector selection
Use the newer WS2815
The wire gauge will depend on the distance between the power supply and the strip.
If it's 4m or less I would use 18 AWG
I like these connectors
@jim-p is correct, here's why. You want to minimize the voltage drop to the LED strip. You can choose your wire based on one of many wire gauge charts or calculators on the web. Here's one I picked at random; with it, you can enter a wire of known gauge that you have handy, enter your distance from power supply to strip connection point, and see what the voltage drop is for a given length:
As a rule-of-thumb, I would always aim for a voltage drop less than 1%, to ensure your LEDs will achieve full brightness. Others may have a different take on this.
Also, keep in mind that once you go beyond trivial numbers of LEDs, the best result will be attained by either feeding power to the strip in the center, or feeding it at both ends. This is because the strip itself will have a non-zero voltage drop along it's length, and that affects the voltage that arrives at the LEDs farthest from the connection point. Center-feeding can be tricky, unless you're good with a soldering iron.
Thanks a lot! The wire I will use is ~2m. If voltage drop less than 1%, I should use 16AWG. But I saw another perspective in this webpage. It sad that " I did a quick test of a BTF-Lighting WS2815 strip, and couldn’t detect any change in brightness over the full 9.5V – 13.5V range.".
At this point, then, maybe you should do a full-scale test? Sounds like the WS2815 may be more tolerant of voltage loss than the 5V WS2812B strips I've used, but only a full-scale test will tell you.
The ampacity rating is how much current you can pass through the wire before you exceed it's temperature rating or in other words before the insulation starts to melt.
I would use AWG18
