Cydia PowerAlerter : Best JailBreak Application
Cydia is now offering a new battery app with a powerful feature that allows user to set alert depending on battery percentage level. The app called PowerAlerter goes ahead of default iPhone battery alert that triggers only when battery drops below 20%.
With PowerAlerter you can choose the battery percentage to trigger the alert, the alert sound, percentage at which the device power down etc.
Note: This Cydia app works only if you have Settings > General > Usage > Battery Percentage on.
The app is available via ModMyi repo and is absolutely free.