This is a great idea. Can even automate it using home assistant for precise control if you're using android. Home assistant's android client reports battery lif

This is a great idea. Can even automate it using home assistant for precise control if you're using android. Home assistant's android client reports battery life to your home assistant instance, so you can write an automation that switched on a smart switch connected to charger when the phone's battery <50% and turn off when it's >95% (or other values optimized for battery longevity.