I created TWO flashable zips to replace the battery icon with the percentage one.
You can flash these is CWM. Let me know if this works. Be sure to make a backup prior to flashing this just in case your phone boot loops.
**I take no responsibilty to anything that happens to your phone**
 Apex_2.0_Battery588.zip is obviously for people who are on System Version 4.5.588.
 Apex_2.0-Battery591.zip is obviously for people who are on System Version 4.5.591.
Thanks to the user who created these battery icons for Apex V1.4.1.