The other hidden cost of running Windows on a Mac: battery life

There’s no denying that Apple makes handsome hardware. Its MacBook Air line, for example, started out as an underpowered and overpriced novelty, but thanks to SSDs and faster Intel CPUs it’s now a powerful little machine.

Apple’s hardware designs are so handsome, in fact, that some people are willing to buy a Mac just to run Windows. But is that a good idea? Maybe not—at least not if you want to get the power and battery life you expect from the components inside.

The problem is Apple’s Boot Camp, which is the only supported way to run Windows directly on Apple hardware. The Apple-supplied drivers are substandard, and they don’t allow Windows to take full advantage of the underlying hardware. I’ve written about this problem previously in terms of its impact on disk and graphics subsystem performance.

And now there’s a body of evidence that documents another hidden cost of running Windows on a Mac. You’ll lose a substantial amount of battery life by doing so.

The good folks at Engadget have been using a consistent test methodology on MacBooks and Windows-powered Ultrabooks for the past year. That collection of data makes it possible to compare machines easily, as they’ve done in a recent review of the new Lenovo IdeaPad U310.

What’s especially interesting is that their battery-life tests on the brand-new 2012 MacBook Air and its 2011 counterpart were done with OS X and with Windows 7. (Engadget’s 2012 MacBook Air review confirms that the Windows tests were performed using Boot Camp.)

I’ve taken the liberty of borrowing that data and refactoring it into a table that ranks the current crop of Ultrabooks and MacBook Airs according to battery life. The results are eye-opening.

The first conclusion to draw from that table is that the current crop of Windows 7-powered Ultrabooks do a very good job in terms of battery life. For now, at least, Apple is the one playing catch-up.

As you can see, the 2012 MacBook  Air running OS X gets very good battery life, although three Windows-powered Ultrabooks (including two Samsungs) outlast it by 7-14%.

The 2011 MacBook Air running OS X is literally in the middle of the pack, with eight current Windows-powered Ultrabooks able to outlast it. The best performer, the 2012 13-inch Samsung Series 9, can run for 90 minutes longer on Windows 7 than a year-old MacBook Air running OS X.

But the really interesting figure for me is how poorly those MacBook Airs do when running Windows 7 under Boot Camp.

The 2012 MacBook Air, which is near the top of the heap running OS X, delivers pitiful battery life on Windows 7. The difference is more than two hours of productivity: 6:34 on OS X, 4:28 on Windows.

What’s really fascinating, though, is to compare performance with similarly configured Ultrabook designs from multiple PC OEMs. A year ago, those comparisons were difficult. Today, the wide availability of Ultrabooks makes it possible to see just how weak Apple’s Boot Camp drivers really are.

Nine Ultrabooks from six different manufacturers, running Windows 7 out of the box, deliver battery life that is at least one hour greater than the brand-new 2012 MacBook Air running Windows 7 under Boot Camp. The new Samsung Series 9 runs more than 2-1/2 hours longer than that same MacBook Air running Windows 7.

I don’t blame Apple for this terrible performance. They’ve focused their engineering resources on their own hardware and their own operating system. For Apple, Boot Camp is a tool to use occasionally, when you need to run a Windows program without virtualization software getting in the way.

If you're a Mac user who occasionally dips into Windows, this isn't an important factor for you. 

But these numbers should serve as a warning to anyone who plans to use a Mac with Windows as a full-time platform. The hidden costs are much higher than you think.