Hello MR members, I got myself a MBA 11" 2013 last year during August which was running ML 10.8.5 and months ago, I upgraded it to Mavericks 10.9. Before that, the battery could last for 8-9 hours on moderate-heavy usage (surfing the web with Chrome up to >10 tabs, watching videos on YT, etc) on ML. After the upgrade to Mavericks, the battery went ******* and could only last for up to 3 hours tops. It was really bad, but I couldn't find the time to downgrade therefore I had to bear with it for around 2 months. 3 weeks ago, I had some time therefore I downgraded it to ML using Internet Recovery. However, battery improved significantly but was still terrible (say 4 hours on moderate usage). I thought upgrading to Mavericks again might solve it, but it didn't. I then downgraded it back to ML for the 2nd time, but still no change. 3 days ago, I sent it to my local authorized Apple Service Centre and the tech personnel found no problem with it. They told me that the hardware check shows that the battery is performing normal and there was no problem at all, with the Battery Indicator stating ~11 hours @ 90% charge. He told me Chrome was a battery hog, but I never had such problems on ML. However, when I'm using it now, the battery has depleted 20% over the course of 30 minutes with 4:47 hours remaining on 64%. Any ways to resolve this issue?