Edible Apple

Promises of long battery life on tech devices tend to be looked at with skepticism. And rightly so. Often times, when a manufacturer says that such and such a product can run for ‘x’ amount of hours between charges, the fine print typically mentions a few caveats, such as screen brightness turned half way down and wi-fi being turned off.

Over the past few product releases, however, battery life on the iPhone and iPod Touch has not only lived up to the hype, but has often exceeded it. The iPad, it appears, is no different.

Apple today lifted the veil of secrecy from the select number of reviewers it let take the iPad for a spin a few days early. Overall, every pre-release review is overwhelmingly positive, but one thing we found particularly compelling were reports of just how long battery life lasted on the iPad.

New York Times reviewer David Pogue wrote:

Speaking of video: Apple asserts that the iPad runs 10 hours on a charge of its nonremovable battery — but we all know you can’t trust the manufacturer. And sure enough, in my own test, the iPad played movies continuously from 7:30 a.m. to 7:53 p.m. — more than 12 hours. That’s four times as long as a typical laptop or portable DVD player.

12 hours of battery life while running non-stop video? Are you kidding me?!

And lest you think Pogue’s experience was an anomaly, Walt Mossberg of the Wall Street Jounral was equally impressed with battery performance on the iPad:

I was impressed with the iPad’s battery life, which I found to be even longer than Apple’s ten-hour claim, and far longer than on my laptops or smart phones. For my battery test, I played movies, TV shows and other videos back-to-back until the iPad died. This stressed the device’s most power-hogging feature, its screen. The iPad lasted 11 hours and 28 minutes, about 15% more than Apple claimed. I was able to watch four feature-length movies, four TV episodes and a video of a 90-minute corporate presentation, before the battery died midway through an episode of “The Closer.”

And just to be clear, Mossberg did all this with Wi-Fi turned on. Unbelievable.

You can be the most passionate Apple hater around, but there’s no getting around the fact that the amount of juice Apple has been able to squeeze out of the iPad’s A4 processor is nothing short of miraculous given its generous 9.7-inch screen.

While many people are attributing the A4 design entirely to Apple’s 2008 purchase of PA Semi, it remains unclear just how involved PA Semi engineers were throughout the entire process. But one area where PA Semi is believed to have stepped up to the plate, and indeed was probably the reason Apple acquired them in the first place, is in power optimization.

Before being gobbled up by Apple, PA Semi was well regarded for designing powerful chips that consumed relatively little power. Venture Beat’s Paul Boutin did a little bit of investigating on the matter back in February.

PA Semi achieved something to write home about just as Apple defected to Intel:  a 65nm 2Ghz, dual powerpc core processor that maxed out at 25 watts.  That was supposedly tantamount to witchcraft, and an explanation I’ve seen for it was that PA Semi was able to break it up into a large number of smaller ‘power domains’ (if that was the term..), allowing them to keep more of the chip either at lower frequency or turned off completely. I also recall reading that this was extremely difficult.

Well, whatever tricks Apple has up its sleeve, they appear to be working.

Related: PA Semi founder and CEO gives Apple his walking papers