In an attempt to quantitatively measure the ThinkPad T440s' battery life in a controlled benchmark environment, we ran Battery Eater Pro. This test is designed to tax a laptop’s resources to give a feel for how long the laptop’s battery will last under heavy use. For the test, we set the T440s' display to 50% brightness and enabled Wi-Fi.
Lenovo didn’t promise any specific time frame for battery life so we didn’t go in with any set expectations, but we found that the ThinkPad T440s performed superbly in our Battery Eater Pro test, topping the field with the slim-profile external 3-cell battery and completely obliterating the group with the external 6-cell battery.
Again, we will underscore that the ThinkPad T440s has an internal 3-cell battery built-in to the chassis, as well as the 3 or 6-cell batteries that you can snap into the underside of the machine, as you traditionally would with any notebook. This gives the machine a notable advantage over most standard notebook designs.
In the web browsing-only test, the T440s also beat out the field, hanging on for over 8 hours before conking out.