This is not an OS feature, and it's not completely new. My original black MacBook (2006) is limited in a similar way - if the battery is removed and the compute

This is not an OS feature, and it's not completely new. My original black MacBook (2006) is limited in a similar way - if the battery is removed and the computer is running on AC power only, the 2 GHz processor is limited to 1 GHz. This happens even under Ubuntu. I don't believe that it happened when my previous near-dead battery was in place and recognized, but more and more often the MacBook would refuse to recognize it, and I'd get the "AC power only" symbol in the menu and a slowed-down CPU. http://web.archive.org/web/20120803114641/http://support.apple.com/kb/HT2332 http://web.archive.org/web/20120803114641/http://support.app...