5 - 10 minutes
Did not want to have to send laptop to apple store for simple battery replacement.
Simple, cheaper, and much more convenient than sending machine to apple store for such a simple repair.
I had to fully discharge and recharge the battery a few times before the system seemed to calibrate the new battery right. Before a few charging cycles it would sometimes stop charging at 98% or 99% full and the charger would turn green as if it were fully charged.
Phillips #00 Screwdriver
Tri-point Y1 Screwdriver
MacBook Pro 13" Unibody (Mid 2009 to Mid 2012) Battery