What good is a notebook that dies two hours after it’s unplugged from the wall? Not much. We’ve created a list of the clamshells that ran the distance on the LAPTOP Battery Test (continuous web surfing over Wi-Fi). Each machine lasts (at least) to the 8-hour marker, but some systems use larger, sold-separately batteries to stay active up to 20 hours. See for your yourself below.
Consider the Lenovo ThinkPad X230 the poster-laptop for systems with optional batteries. The 12-inch ultraportable ships with a 6-cell battery that lasts a decent 7 hours, but the sold-separately 9-cell option pushes the juice supply beyond the 12-hour mark. If that's not enough productivity time for you, the X230 also works with a sheet-battery that, when paired with the 9-cell, helped the system run an epic 20 hours!