When we reviewed the Acer Aspire S7-391, we loved the gorgeous industrial design and 1080p touch screen. But one of our chief complaints was that the Ultrabook's battery lasted just 4 hours and 10 minutes on the LAPTOP Battery Test (Web surfing via Wi-Fi). That's 2 hours less than our ultraportable category average, and hardly what you want to see out of a $1,699 notebook.
Fortunately, Acer released an external 2,500 mAh battery that promises to extend the S7's runtime considerably. How did it fare on our tests?
The external battery extended the S7's life to 9 hours and 17 minutes, about 5 hours longer than the battery in the notebook itself, and about three hours longer than the ultraportable average.
Unfortunately, the external battery attaches somewhat awkwardly to the S7. You have to screw the battery into the bottom of the notebook, and the plug it into the S7's power port. The plug itself juts out about 3/4 of an inch, which made us worry we'd accidentally snap it off. It also increased the weight to 3.4 pounds, up from 2.8 without the battery.
However, the battery did alleviate one problem: In our initial review, we noted that the front edge of the Aspire S7 dug into our palms. With the battery attached, the rear of the notebook increases about 0.75 inches, which tilts the front downward, and no longer digs into our hands.
The battery costs $150; unlike the smaller Acer Aspire S7-191, it's not included with the notebook. For this kind of money, Acer should bundle the external battery. It's not pretty, but it supplies the kind of endurance you would expect from an Ultrabook.