iOS 5 has brought many needed and welcomed features to all Apple devices. One important thing Apple overlooked was a notification banner for low battery levels. They did include a low battery level alert which requires the user to dismiss. This can be very annoying should you be playing a game or texting someone important. I can’t count the times I have received this alert during Facetime calls. This is very intrusive to say the least.
The developer called, snakeninny has released a free, Cydia tweak called LowPowerBanner in BigBoss repo. The tweak sends a notification banner when battery levels reach 10% and 20%. It also includes a very pleasant chime with the notification. The notification banner includes an exclamation with the alert to show importance for the notification.
I think this is a tweak everyone will want to add to his or her devices. It works on all Apple devices. No settings to configure or icons added. The only requirement for the tweak to work is iOS 5. That should be obvious since iOS 5 brought notifications. Are you going to download the tweak? 
It doesn´t work in iOS 6