[Pajamaman]

My Onyx (a nova generation 1) can be switched between power saving mode and normal mode. power saving mode shuts down background processes. the power saving / normal mode is a battery icon that show when you click the top of the screen in the home screen.

edit: kind of related. if you go to the apps page, there is an snowflake icon in top right that allows you to freeze processes.

edit: if you go to power settings and click battery status it shows what is using power. The biggest for me is table idle at 11% and android os at 5%