Replace MacBook Pro (13-inch, Mid 2012) battery from MacBook Pro (13-inch, Early 2011) The macbook i am using currently is MacBook Pro (13-inch, Mid 2012). Now the battery warning is "Replace now" state. So i need to change it. I have another macbook with MacBook Pro (13-inch, Early 2011).  

Is it possible the replace battery from MacBook Pro (13-inch, Early 2011) to MacBook Pro (13-inch, Mid 2012) ?
Yes, it is possible to swap the battery from a MacBook Pro 13" (Early 2011) to a MacBook Pro 13" (Mid 2012) model. In fact, the same battery is used from Mid 2009 to Mid 2012 in all 13" MacBook Pros. You will need a special screwdriver called a tri-wing screwdriver though, to remove and reinstall the battery.