Phone will inform you when it's charged to 100%.
Just connect the cable.
To disable the sound signal, disconnect the charging cable from the device.
The ringtone will playing in Ring/Silence modes. Use volume buttons to change the ringtone volume.
Use Widget for fast launch of app.

● 2 modes
Mode 1. (Foreground)
Screen Autolock is off.
Screen brightness is reduced automatically.
At 100%, display flickers, starts vibration and sound signal.

Mode 2. (Background)
Screen Autolock is on.
App works in background mode.
At 100% battery, starts vibration and sound signal, notification appears on the lock screen.
During charging, the launch of Siri disables the application.
If power is off, app sends "Battery doesn't charge" notification.

●3 ringtones + 3 relax music
Choose a sound signal that you like.