Get Custom Battery Percentage Level Alerts For Your iPhone, iPod touch and iPad [Jailbreak Tweak]
Although iOS alerts you when the device’s battery drops below 20%, you might want to change that to something higher or lower depending on your preference and you can do that with PowerAlerter.
With this tweak, you will get alerts (visual, haptic and audio) if the charge of your iOS device will drop under a certain percentage.
You can obviously choose at what percentage to trigger the alert, the alert sound, what percentage for the device to power down etc. PowerAlerter only works if you have Settings > General > Usage > Battery Percentageon.