If you use any task killer or Ram cleaner app or Antivirus Apps then kindly add this app to ignore list or white list. Otherwise, battery alarm may not work properly. FOR XIAOMI, OPPO USERS: In the security settings given by Xiaomi & Oppo default, please include the app for auto start. In some phones you need to turn on auto start option in background run setting.
Download the installer of Battery Full Alarm 109 free of charge and take a look at users' reviews on Droid Informer. The app runs on Android devices 6.0 and above. This application is totally safe to download. Udhyama WoodTech Apps is the developer of Battery Full Alarm that can be found in the Tools category.