I'm typing on my 2013 MBA (11-inch) refurb that I just picked up at the Apple Store. The battery is showing 100% but when clicked on, it says "4:34 remaining." I thought the battery was supposed to last 8-9 hours and am concerned that something could be wrong, hence why it was sold as a refurb. Is there a way of checking whether something is wrong with the battery other than the System Report on the computer itself which reports the battery condition as "Normal" with 12 cycles.