The biggest consumers of battery power are applications that run automatically when the smart phone ignites. Those are apps like Facebook, Facebook Messenger, Kik, and WhatsApp. These applications run constantly in the background and are constantly connected to the Internet...
Permissions required for Messenger:
Identity - find accounts on the device / read your own contact card
Contacts - read your contacts /Location
approximate location (network-based) / precise location (GPS and network-based)
SMS - receive text messages (MMS) / receive text messages (SMS) / send SMS messages / edit your text messages (SMS or MMS) / read your text messages (SMS or MMS)
Phone - directly call phone numbers / read call log
Photos / Media / Files - read the contents of your USB storage / modify or delete the contents of your USB storage
Camera - take pictures and videos
Microphone - record audio
Wi-Fi connection information - view Wi-Fi connections
Device ID & call information - read phone status and identity
Other - receive data from Internet / download files without notification / read sync settings / view network connections / install shortcuts / control vibration / run at startup / change your audio settings / draw over other apps / full network access / change network connectivity / read battery statistics / send sticky broadcast / prevent device from sleeping / read Google service configuration
Massively invasive, privacy murdering, baby eating, battery hog...