In the following benchmarks we employ two very different battery life tests, Battery Eater Pro and a custom 1080p HD video loop test developed in-house, to prove out battery life with our test group of machines. In all tests, Windows 10
Quiet Hours has been enabled and the displays are calibrated with lux meters
on pure white screens to as close to 115 lux as possible. For the average laptop this is somewhere between a 40 - 60% brightness setting. Since laptop 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. And, since many laptop displays vary in brightness at each respective setting in Windows, this calibration with the meter is critical to ensure all displays are set to as near identical brightness output as possible, before running battery tests.
Battery Life - How We Test:
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 up-time, every minute -- along with the grand total -- before system shutdown is stored and logged. This is a lighter-duty test that is still a bit more strenuous than many office productivity tasks, but it's not nearly a taxing as the load the Battery Eater test we'll have next puts on a system.
Lenovo's new ThinkPad X1 Carbon lands in the top quadrant here and only trails machines with 1080p displays. Even though the machine weighs just 2.49 pounds, with its 57 Whr (Watt Hour) battery on board, and this new LTPS display Lenovo chose, this new ThinkPad puts up impressive always-on battery life, especially at its 1440p resolution. Dropping back to the 1080p display option will likely afford even better battery life, though you'll miss this panel's 500 nits of HDR
punch. Either way you slice it, over 7 hours of always lit up-time is solid for a machine with such a crispy display is nice.
Battery Eater Pro wears a machine down much more quickly by placing a heavy load on all laptop subsystems, including processor, graphics, memory and even some file transfers to storage. This is truly a worst-case test that will give you a sense of how a machine will hold up under heavy strain, when under taxing, continuous content creation workloads, for example.
In this battery stress test, the 2018 X1 Carbon didn't fair so well. This is likely due to the top-end configuration we received with not only 16GB of RAM but also a more power-hungry 8th Gen Core i7-8650U processor on board that turbo boosts to 4.2GHz. If you need that extra horsepower, you'll be thankful for it in quick bursts perhaps, though you'll be more often tethered to a power outlet if you're continually pushing the system and spooling up its cooling fans.
ThinkPad X1 Carbon 6th Gen Acoustics & Thermals
Speaking of which, the ThinkPad X1 Carbon
configuration we tested has a bit of a split personality. Under heavy load the machine remains relatively subdued acoustically, with its cooling fan emitting only a dull whir at an octave we'd thankfully not
describe as a whine. Even under a gaming workload, when plugged into AC power, the machine remains completely unoffensive from a noise output standpoint. Thermally, things can get a little warm on the underside of the machine when under load, but again, things remain in check and comfortable enough.
However, the 2018 X1 Carbon's default fan and power profile seems a little conserrvative, in terms of supporting the thermal headroom required for the top-end processor configuration we tested (Intel's Core i7-8650U
quad-core Kaby Lake R), when it's placed under sustained load. As such, we'd suggest maybe choosing a configuration of the machine with a Core i7-8550 or even a Core i5 8th Gen quad-core variant, which will be plenty of horsepower for mainstream use cases. Fortunately, Lenovo offers a wealth of configuration options
for the machine, with the ability to configure 8 or 16GB RAM setups (integrated on the motherboard so buy up if you can and future-proof), and the display option of your choice, with a number of Intel 8th Gen Core processor options.