During the Macworld 2009 keynote address, Apple revealed that the new 17-inch MacBook Pro featured a huge, built-in battery pack, which offered its user eight full hours of work time. Apple called this a true breakthrough in battery-life. The company decided to let everyone in on how it did it.

Just like it did with the 13-inch unibody MacBook, Apple released a making-of video for the new 17-inch MacBook Pro, with an emphasis on the system's battery. In the video, Bob Mansfield, SVP of Mac hardware, explains that the 17-inch Pro features a revolutionary new, built-in battery that delivers up to eight hours of use, and up to 1,000 recharges for more than three times the lifespan of conventional notebook batteries.




“With batteries, size matters,” Apple says. “The greater their capacity, the longer they run. The challenge is that the real estate inside a notebook computer is limited. Millimeters matter. Most computer makers deal with this by jamming as many lithium-ion cells as they can into a removable battery pack, adding bulk to the system. There are a few problems with this approach. First, lithium-ion cells have fixed cylindrical shapes (they look like traditional AA batteries), and they dictate the thickness of the notebook,” the company explains.

“Also, valuable space is wasted in the cavities between the cells. To increase battery life without increasing the size and weight of our notebooks, Apple scientists and engineers used lithium-polymer. This type of battery can be customized to fit perfectly inside extremely thin enclosures, like those of the MacBook, MacBook Air, and MacBook Pro.”

But this was not enough for Apple's engineers. To make the lithium-polymer battery even bigger, they eliminated all the parts required by a removable unit and embedded it into the notebook. Although this prevents users from replacing the battery themselves, it creates enough space for a battery with 40 percent greater capacity. Plus, with such a long lasting energy storage solution (both in the short and long run), who needs to buy a new one before the system is obsolete?




“The battery in the new 17-inch MacBook Pro is made to be smart,” Apple goes to explain. “It’s built with a chip that talks to each of its cells to determine their precise condition. The chip shares this information with the computer. And the computer uses an advanced algorithm to make delicate adjustments to the charging current, varying it to suit the changing conditions inside the cells. This Adaptive Charging reduces the wear and tear on the battery, and gives it a much longer lifespan than ever before,” the company reveals.

Furthermore, while most users are taking all this for granted, what could possibly lie at the heart of this breakthrough in battery life? Well, according to Apple, “Charging is only part of the story. The battery innovations in the new 17-inch MacBook Pro go deeper — into the very chemical makeup of the battery,” the Mac maker explains. “Apple’s team of scientists and electro-chemists developed advanced chemistry that extends the battery’s lifespan even further.”



So, it was all thanks to the breakthroughs of advanced chemistry and Adaptive Charging that made the battery in the 17-inch MacBook Pro capable of going through up to 1000 recharges “before it reaches 80 percent of its original capacity.” Yes, this means there's a few dozen charges left, even after it is officially pronounced dead.