5 - 15 minutes
Received a notice from software that the battery in my early 2011 MBP 13" was failing.
The repair was smooth and easy, given the video documentation and repair manuals I saw on ifixit.com.
Take your time and use the right tools.
Tri-point Y1 Screwdriver
MacBook Pro 13" Unibody (Mid 2009 to Mid 2012) Battery