I am thinking about building a sort of power control unit for pi zero using a small arduino.
The idea is to use the nano to both measure the voltage in a battery and keep pi informed about the status and for a smart shutdown.
Pi would in turn have something running in the background that would ideally update status in the system tray, but certainly provide critical level warnings and there would be some sort of calibration app (to calibrate what is critical for a particular setup).
The communication would be via gpio serial and probably another pin for simple indication that raspberry is up/down.
Arduino would control the power via single mosfet and there would be a single button for rebooting/shutdown/wake up (depending on the state and length of the press). Likely arduino would have to run all the time (or at least I have not figured this part out yet), but could go into a very slow mode while pi is down so that battery drain is very minor.
Has anyone heard of a similar project? And if not, why not, it does seem quite obvious, so what am I missing?
Also, any advice on which mosfet would be suitable would be fantastic.