[gregoriol]

First things first: you could develop a custom interface within your app, think of games for example, to show the battery level, or simply an icon when it's low, in a specific way instead of the system's style.

Then, depending on what your app does, you can act on a few things to reduce, or not, battery usage when it gets below some thresholds: reduce GPS precision, remove some animations, limit framerate, make less networking requests, ... It could be limited by the system, but it would probably not be as wise regarding to what is important in the context of one app vs another.

We have numerous cases where we adapt to the battery level so the user can get the best of our apps and not empty their battery while they still need it.