He decided instead to use an Arduino to monitor the 3.3V power rail on the Pi. When the Pi is shut down in software, the Arduino can sense that the Pi isn’t on any more and disconnect the power.

It's also a great idea to connect a switch for the battery, so you can turn the power on and off as needed without unplugging the wires. Use the Pin 27 5V pin shahzada farrukh/Shutterstock ...

I made this Arduino project that allows to turn ON and OFF LEDs using a cheap IR remote control as a preparation for the next big step: disassemble my girlfriend’s chinese LED lamp and replace its ...