★ June 29th, 2009 Walter Mossberg on new batteries
The smaller of the two machines lasted a few minutes shy of five hours in my test. And the larger one lasted five hours and 21 minutes. I estimate that, in a more normal usage scenario, both machines would come close to Apple’s claim of around seven hours between charges—essentially a full workday of unplugged use. Those numbers are likely to obviate the need for spare batteries for the majority of average consumers.