Power to an onboard Rasberry PI (as used for nav)

[Forty_Two]

The hard bit is to deal with power being switched off accidentally.

Does anyone have a small UPS which can communicate the requirement to run 'shutdown -h now' to the Pi?

Not on my nav Pi. They are much better at handling mishaps these days. Ocpn less so i fear. Never had an issue as fed by it's own circuit breaker. I would advise anyone using the Pi to use the excellent Pi clone program to make regular copies. Just need a usb sd card writer & some spare sd's.

For my touch screen pi system which shows various temps, volts & amps from around the boat, as i am running my own Python program it monitors the master Dc switch & shuts down the Pi when i turn everything off when leaving. A good old fashioned relay is held on for 20s by a capacitor to allow the Pi to shut down gracefully before disconnecting power.

 

[Forty_Two]

The hard bit is to deal with power being switched off accidentally.

Does anyone have a small UPS which can communicate the requirement to run 'shutdown -h now' to the Pi?

Thinking about this a seperate ups is another battery to worry about.

The boat is your ups feeding the 12v to 5v convertor. You just need to have a secure feed with a circuit breaker that's not next to others you might regularly turn on/off.

 

[cpedw]

The hard bit is to deal with power being switched off accidentally.

Does anyone have a small UPS which can communicate the requirement to run 'shutdown -h now' to the Pi?

Not a UPS but I did devise this scheme to achieve safe on/off of a Pi4B from 12V. It's controlled by a momentary switch which switches on the supply and delays switching off until the Pi has closed down.
Derek