Lenovo ThinkPad X1 Ultralight Laptop Review

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Battery Performance

If there's one thing a netbook (or an ultraportable) needs to be really competitive, it's great battery life. No matter how great the software or the hardware, an ultra-mobile machine needs great battery life to be really useful in the field. This, unfortunately, turned out to be the ThinkPad X1's Achilles heel.

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.

Things are better here but not great. The X1 only outpaces the X120e or the U260 by 28 percent, and it requires two batteries to do it.  To be fair, however, the processors powering the two other Lenovo systems here are much lower-power devices. Regardless, on just one battery the system falls short of three hours. That makes the Slice battery a near necessity and adds another $149 to the price tag, though with this option you'll survive almost 5 hours untethered.

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.

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