Software is nowhere near as good a good resource management from the user can be.
If he kills and disables all unused apps, turns off all auto updates and notifications, and keeps his screen to the lowest usable luminosity, he can gain in battery life without an app. Manually updating and syncing of one's things isn't all that hard, and doing it 2, maybe 3 times a days should suffice for most people, to remain functionally connected to our respective environments and social circles.
I suggest using a portable battery type of charger if power outlet availability is an issue. Amazon and most consumer electronic stores has them, in varying quality and prices. They typically look like
this one.