[Macpartners] MacBook Air 11" battery life

[Felix Kreisel]

Hi, 

I have a battery life problem with a new MacBook Air 11" purchased in mid-2012. The MBA came with 10.7.4, and I upgraded to 10.8.1, then to 10.8.2. Battery charge used to last 6+ hours until I upgraded to 10.8.2. Then I started to notice a dramatic decrease in actual life, down to 3-to-4 hours. My mix of programs did not change between 10.7 and now: Chrome, Dreamweaver, Mail, Calendar; I always turn Bluetooth off, and keep the screen intensity at about half.

Peculiarities that I noticed with 10.8.2: After waking the laptop from sleep by lifting the lid it indicates a 100% charge, but during the next few minutes it tells me it is "calculating time remaining". It keeps recalculating. Now at 96% it tells me I have 3:56 remaining. When connected to the charger, the battery monitor also calculates "time until full charge". This calculation is also peculiar. E.g. at 98% charge, the battery meter told me that it would take 27 minutes for a full charge". It only took about 5 minutes.

There is also the ever busy Wifi scanner. This has been an ongoing feature (bug) of the OS. The Wifi is constantly scanning for networks.

The Activity Monitor is useless since it tells me that the laptop is using 7-10% of CPU, i.e. basically, the laptop is not busy.

Apple is willing to replace the battery, if I request, but I don't think there is anything wrong with the hardware. I have read that Mountain Lion (10.8) was bad for batteries, that 10.8.1 made some fixes, but in my case 10.8.2 was a battery killer.

Does anybody have any ideas of what is going on?

Felix Kreisel - Systems Engineer,
Plasma Science & Fusion Center, MIT
617-253-8625   fjk at mit.edu