I bought a MBA 13 i5 250GB and 4GB RAM, not entirely what I wanted but being based in Thailand at the moment, I would have had to wait for 3 weeks for an i7 with 8GB RAM to come from Singapore. Given that my old one had just died, I had to bite the bullet. I figured I would change when back in the UK.
Upon un-boxing , the battery showing 100% quoted 12 hours, impressive I thought, BUT lets wait and see.
I immediately starting installing all the usual apps and was still very impressed. Battery seemed to be as good as the claims. I figured that I couldnt really tell yet as no doubt it was getting extra usage from installing and indexing.
Day 2
Used the MBA at work all day, emails, Internet, PDF's etc, lasted approx 8 hours. Not so good as day 1
Day 3
100% charged overnight, much the same as day 1, in addition viewed some clips on YouTube, battery died after 7 hours.
Day 4
Watched a movie in VLC, surfed the Internet, wrote some word docs, emails, downloaded files-total approx 3GB, again approx 7 hours battery.
Day 5
Same menial tasks as above, battery died not long ago, again 7-8 hours.
Now bear in mind I am running an i5, no heavy apps running, checked Activity Monitor daily, no indexing going on.
I am not getting the battery life that I expected, or that I bought the MBA for.
Obviously I will keep monitoring the situation, if it doesn't change I feel it will be going back to the Apple store.The battery indicator certainly appears to be of very little use, other than to make you feel both pleased and then disappointed.