This is an Xposed module for Android Lollipop/Marshmallow (5.x.x/6.x.x) that adds the current battery percentage to the lock screen, notification shade header, and status bar. The app includes options for enabling or disabling the injected text, changing the position of the text relative to the battery icon, and changing the appearance of the text.
Note that this has not been tested on Nougat (7.x.x). As of Oreo (8.x.x), this module is no longer needed, as the battery percentage text is now properly shown alongside the battery icon when enabled in the System UI Tuner.
The latest version can be found on the Releases Page as well as the Xposed Module Repository.