Most iPads will use 10%-20% of the iPad's battery per hour. iPhone battery life will vary greatly based upon individual usage habits. To maximize your iPad or iPhone battery run time, ForeFlight suggests the following:
1. Close all other apps running in the background.
2. Reduce brightness as much as practical.
3. If using iOS 8.3 or above, turn on Airplane Mode when flying. This will disable all broadcast functions (Wifi, Bluetooth, Cellular Data) while leaving the internal GPS receiver enabled.
Note: you may need Wifi and/or Bluetooth turned on if you are using Stratus, an external GPS, or a bluetooth headset.
Adding an external charger will also increase the battery run time, however, some devices will continue to lose charge even with a charger attached. You can learn more about ForeFlight recommended chargers in our Buying Guide.