Continuing the discussion from Feedback for v2.1:
I noticed that there were several reports about FP4 battery drain issue which started to happen after upgrading to v2.1. Here I would like to share a possible (but obviously temporary) way of mitigating the issue: use the free software app Timed Shutdown and alarms.
The app basically uses accessibility function natively implemented on the OS and emulates the tap to shutdown the phone per user’s settings. The timing can be set with a timer or as schedules.
Since FP4 is automatically powered on several minutes before ringing alarms, you can set your phones to be switched off with the app when you go to bed, and the phone should be automatically powered on before the alarms. If you do not really want to be disturbed with them, you can set a custom audio file without sound.
The apparent drawback is that the phone cannot receive a phone call while it is switched off.
This “solution” works for my FP4 on v2.0 to reduce battery usage (fortunately, I rarely get a phone call on midnight or early morning). I am not perfectly sure if this would work on v2.1 as well, but I would like to share it anyway, hoping it would help those who are affected with the issue.