Apple released an SMC update today for many of their 2010 and 2011 MacBooks, fixing a bug which could affect the battery performance of the affected devices. There are three separate versions of the update, for the MacBook, the MacBook Pro, and the MacBook Air.
From the release notes:
About the update:
This update addresses a rare issue on some Apple notebooks where a battery that has accumulated more than 1000 charge cycles may unexpectedly shut down or stop functioning.
The updates are available now through Software Update on eligible Macs, as well as for direct download from Apple using the above links. MacRumors provides a list of every MacBook eligible for the update:
MacBook
- MacBook7,1 (13-inch, Mid 2010)
MacBook Air
- MacBookAir3,1 (11-inch, Late 2010)
- MacBookAir3,2 (13-inch, Late 2010)
- MacBookAir4,1 (11-inch, Mid 2011)
- MacBookAir4,2 (13-inch, Mid 2011)
MacBook Pro
- MacBookPro7,1 (13-inch, Mid 2010)
- MacBookPro8,1 (13-inch, Early 2011 or Late 2011)