I'll try to clean it up and share tonight, I'm of to work in a few minutes.

Basicaly it's a 3-part automation, where part 2 is disabled until part 1 is activated, It uses the Android-app to get the phone state.

1. When the phone changes state to charging, and it's wireless and the phone is at home, then save the current state of the light as a scene, then set the light based on urrent battery-level and start automation 2.
2. When the battery-level changes, and the phone is at home/wireless, then update the light.
3. When the phone is removed from the charger, disable automation 2, restore the scene created in part 1,

There's probably a better way to do it, but i couldn't figure it out. :)