How do I replace the pram battery for my late 2011 Macbook pro?

You can take it to a Genius bar for a free estimate, maybe even call.

http://www.apple.com/retail/geniusbar

http://support.apple.com/kb/index?page=servicefaq&geo=United_States&product=Macn otebooks

Check online, search replace pram battery macbook pro, you will need to know your model number/year, to get the right one and the correct proceedure.

Here are some examples:

http://www.ifixit.com/Guide/MacBook+Pro+15-Inch+Core+Duo+Model+A1150+PRAM+Batter y+Replacement/490 Older one easy fix

http://www.ifixit.com/Answers/View/115589/PRAM+battery,+can+I+replace+it+myself newer ones become more involved

http://www.dvwarehouse.com/Apple-Back-Up-Battery-c-253_238_5631.html?gclid=CNW87 a_Rwr4CFXQ1MgodaQwAdA

Identify model:

http://support.apple.com/kb/HT4132

As you can see there are a few batteries and you need to use the correct replacement, as well a do the proceedure correctly.

Hope this helps

Which MacBook Pro model do you have (e.g., "15-inch Late 2011")?

Most newer machines don't have a PRAM battery.

Clinton