You can choose which percentage will trigger the alert, and you can sent PowerAlerter to play an audio alert even if you are in silent mode. Also you can choose if PowerAlerter should power off your device if a certain percentage is reached. PowerAlerter offers several warning sounds, you can select within the settings.
NOTE: currently, PowerAlerter will work ONLY if you have General>Usage>Battery Percentage turned ON. Hopefully this will be fixed in the next update.
PowerAlerter is available for $$ ( price isn’t displayed ) in Cydia Store via modmyi repo…