My Air 2 has never had a great battery, I have NEVER got the advertised 10 hours or even close, 7.5 if extremely lucky with half brightness, bluetooth off, and everything else optimized for battery life. For the first time ever I just now plugged it into Coconut Battery and its at 75% capacity after just 321 cycles. Figures, should've done something about it a long time ago. Oh well.
/rant
/rant