OS X Yosemite: If your battery’s status is “Not Charging”
Your Mac is connected to a power source that gives it enough power to run but not enough to also charge its battery
If the Battery Status menu on your portable Mac says “Not Charging,” your computer is connected to a power source that gives it enough power to run, but not enough power to charge the battery. For example, your Mac might not charge when it’s connected to an airline power adapter.
You can still use your Mac without draining its battery, but the battery will not be charged, even if you turn off your Mac or put it to sleep.
Last Modified: Sep 23, 2015