That’s weird, I wonder which program did it.
I typically get a day of work out of my Zenbook flip 13; I haven’t really measured the battery performance rigorously because it is easily long enough that I don’t think about it (the battery indicator will say 14 hours, but those are of course pretty flaky). I’m a vim/Firefox with ads blocked guy though so I guess I must not be making it work very hard.
I also have a Anker 737 battery, with it I can double the macbook's battery if fully charged. The Thinkpad would only charge partially, so wouldn't even double.