The worry is that battery technology isn’t improving at the same rate as the rest of the technology for our smartphones. The are some of the culprits for your battery.
Streaming video
Streaming takes a huge amount of resources. The processor need to decode and play the video and audio; Since your are watching it requires your screen to be on the entire time; your phone needs to load the video using data or Wi-Fi. All the above explains why your battery life would be less if regulary watch videos.
Navigation
Similar to streaming video, using your phone for directions navgation can strain the battery because of the resources required like sceen, GPS, data or WIFI. As you are doing your turn by turn the system will be refreshing the satelite signal at a higher pace, so that you can know where you are.
Forget the facebook app, use a browser instead.
Why not just log in to Facebook on your mobile browser? If that’s a compromise you’re willing to make, you can save up to 15% of your iPhone’s battery life, according to testing done by a journalist at the Guardian.
The Facebook App is notorious for taking up your iPhone’s battery because it has to refresh regulary and determined your location (if its turned on) hence using up much your battery.