Battery Life Testing
Medium Workload Test Conditions
The ThinkPad X1's Slice battery in action.
The Lenovo's 'Slice' battery has gotten a fair amount of attention, but we've noticed a fair degree of confusion over what the X1's battery configuration actually is.
The Lenovo X1 has two batteries. One of them is a four-cell battery integrated into the system and can't be removed without voiding the warranty. The other is the six-cell "Slice" battery, and it attaches to the bottom of the system via a series of latches. Lenovo claims it can charge the "Slice" battery to 80 percent within 30 minutes; our experience indicates that the battery does charge extremely quickly, though we didn't formally time it.
It's a good thing it does; you'll be recharging it frequently. The results of our first battery test are below.
Can we say ouch? Even with both batteries installed, the X1 barely breaks 1.5 hours. For our next test, we used Lenovo's own power utility to set the system for Maximum Battery Life.
Opting for an SSD instead of an HDD might gain back a few minutes of run time, but Lenovo's "Maximum Battery Life" mode is very thorough. Screen brightness is reduced dramatically and an entire range of power management features are tuned for rock-bottom consumption. Lenovo offers what it calls "Battery Stretch," but that technology is of little help when you're already optimized for minimal power consumption. On a 4hr 37m charge, the system predicted we'd gain three minutes of life by using battery stretch.