Sadly I've been trawling several forums looking for an answer but seems there is none, other than the battery reboot which doesn't work btw. For what it's worth, this only happened directly after the 11.1 upgrade. Now the battery "chooses" when to charge so if I'm not careful it can shut down, EVEN IF ITS PLUGGED IN. I get the message that although it's showing the thunderbolt of charging, when I click the battery it says Battery Currently Not Charging.....