Yep, that's smart! I will start building a prototype (when I have time...)Just use an Y for the XT plug that comes from the battery or the charge plug, with a 36/43v->5v limiter that will work and cables are shy 10cm from the seatpost
I was thinking maybe the lights could be triggered by the Bafang remote, and there was a way to even avoid the dedicated remote! that could be awesome, but I guess it will require more testing.
I need to understand what exactly triggering the lights does (is it just providing the voltage to the cable lights ? if yes, it could be used if we connect it to an IN PIN on the Arduino to trigger the servo...)