ThinkPad X1 Battery Life, How We Test, and Acoustics
In the following benchmarks we employ two very different battery life tests: Battery Eater Pro and a custom 1080p HD video loop test, to prove out battery life with our test group of machines. In all tests, Windows 10 Quiet Hours have been enabled and displays are calibrated with lux meters on pure white screens to as close to 115 lux as possible. For the average notebook this is somewhere between a 45 - 60% brightness setting. Since notebook displays significantly affect power consumption and battery life, it's important to ensure a level playing field with respect to brightness of the display for battery testing. However, since many notebook displays vary in brightness at each respective brightness setting in Windows, this calibration with the meter is also critical to ensure all displays are set to as near identical brightness as possible before testing.
Just as we saw with Lenovo's Yoga 700, the ThinkPad X1 Tablet only lasted a little over 2 hours before it ran out of stamina. That's a little more disappointing on a 2-in-1 aimed at business professionals. We don't necessarily expect all-day battery life here, especially considering its raw performance, but 2 hours leaves much to be desired. The saving grace is that Batter Eater Pro is a stress test that's more indicative of a worst case scenario.
Our custom HotHardware video loop test takes a 1080p HD video with a 16Kbps bit rate and loops it repeatedly, with 1 minute break intervals in between. A timer log file increments minutes of uptime every minute and a final minutes total recorded before system shutdown is stored in the log. This is a lighter duty test that is still a bit more strenuous than say many office productivity tasks, but it's not nearly the strain that Battery Eater puts on a system.
In our video loop test, the ThinkPad X1 Tablet managed to stay active for 3 hours and 44 minutes, or nearly double the time it stayed awake while running Battery Eater Pro. This is more indicative of real world performance and it amounts to almost half a typical work day. It's a better showing, but still not great.
The good news here is that these results don't have to be the end of the story. If you need more battery life, Lenovo promises a 5 hour boost with its optional Productivity Module. That's a better proposition than what the 2-cell (37 Whr) battery can offer by itself. And keep in mind, the screen is lit constantly throughout all of this testing -- with lighter duty workloads and idle time added in, real-world battery life with typical usage will be much longer.