I pre-ordered the 2018 Mac Book air. Out of the box, I've been experiencing poor battery life. I'm getting about 6 hour battery life. To fully charge, my charging estimate is typically 3hrs. On one evening while on sleep, my battery completely drained. Today, I started my morning with 60% battery, I've used for a little over an hour and I'm at 13% Any one experiencing this issue? Any suggestions?