Apple pre-configures iPhones to automatically shut down when the battery level dips below a certain percentage, but many users find this feature more interruptive and bothersome than It’s worth.
With a new free jailbreak tweak called Last Drops 10 by iOS developer Ilia Kambarov, you can make use of every ounce of power stored in your battery; even during those critical moments when your battery hovers around ~1%.