That's good battery life. Since my last comments, I've received 2 replacement SP4, the first one had good battery life, draining around just over 10% per hour with just web use, however the screen flickered very badly so I ended up exchanging for another. My second replacement has poor battery drain, no improvement over my original, 20% drain per hour giving around 5 hours. I'm not happy to keep and will be requesting another replacement. If there is no improvement in the 3rd one then I'm going to see what my options would be from Microsoft.I haven't posted here in awhile since I haven't really done any solid battery use until today. Today, I was at a conference where I was taking notes in OneNote as well as using Chrome to look up webpages and viewing the programme pdf with Xodo Docs. My SP4 was screen on for 307 minutes (5.1 hours), on overall for 10 hours including sleep, which drained 69% of the battery. This would lead to a projected battery life of 7.4 hours. This is only one data point but might indicate that the recent updates might have improved battery life a little bit.