Did you have any issues with hooking up 15 LiPo cells in parallel? It looks like you have a bunch of them going into a junction box, what's inside there?
the RGB-123 use WS2812B-10 leds
the datasheet rates them between 3.5 and 5.5v
some guys had trouble running WS2812B at 5V with 3.3V signal levels.
turns out the WS2811 datasheet says that the signal / power ratio should be no less than 0.7.
running the whole setup at 3.7-4.2V from the lipos means that we are well within the 0.7 ratio with our 3.3v signals.
thats why i run them DRIECTLY from the lipos and use no levelshifters or step-up converters anywhere.
the box is just a bunch of JST connectors and fat wires to transport the current away safely.
everything worked out much better than expected :)
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