Whilst I am ok with the IT side of the Pi my electronics knowledge is poor. I am looking to power my Rasp Pi 4 4MB and basic camera in my car, so I need a cigarette lighter socket power supply or a battery pack. I would like about 20 minutes power if a battery pack. I do not want to start hard wiring into car power circuit. I have read enough that I have confused myself and I am unsure what I need. Is there a way though the power provider to force a clean shut down or can you use software to monitor battery life and close down before the battery runs out?
Any help or pointers would be great.