Hi Forrest, I’ve had a few laptops over the years which met or exceeded the results observed from Notebook Check. These are their results for the 7840u.
I run linux and have been fine tuning the power usage on my FW13 7640u and have shared my experience here.
TLDR: after some test & tune, I’m seeing 10-11 hrs of use on my FW13. Notebookcheck reports 12 hrs of use from the 7840u powered FW13 on Win11.