I'm working on setting up an arduino powered ambilight for my living room. I ordered a 5m string of WS2812 LEDs, 60 per meter, 300 total. I only plan to use about 140-150 for my project, but I'm testing w/ the full string. I'm powering them with a 5v 20A power supply for testing, but have a 10A I will be using in the final setup. On my first test I tried lighting up all the LEDs white to test the max draw, but I was getting yellowing down the strip until the last LEDs were just red. Checked with my volt meter and I was getting 2.3v at the end of the strip. I connected power at both ends of the strip and got a full 5v through the strip and tested again, all white down the line.
Now here's where things my math doesnt add up. Like I said, I expected to pull 18A from the power supply for 150 LEDs. I plugged the supply into my kill-a-watt and monitored the amps. With all 300 LEDs lit up full white it shows an amp draw of 1.04 amps. That can't be right, can it? I would understand if it was off by an amp or 2, but 1/20th the expected power draw? Am I just getting lucky or reading things wrong?