Storm Shield uses Significant-Change Location service (not GPS) which is part of iOS Location Services. This provides a low-power way for apps to get a device's current location without using GPS and still be notified when significant changes occur. This has a minimal effect on battery life. Battery life depends on a variety of factors such as the version of iOS your device uses, the age of your device and its battery, and other apps using your location (for more information on Apple Location Services, click here).