Thank you for the information.
In this case, we would need to dig in more on your settings when you have 3.5 hours battery usage.
Your device is i5 or i7 version?
What kind of program were you using? was the screenpad on?
What's the screen brightness, volume, Wifi, bluetooth...
you may also check in task manager to see if there is any specific function that is consuming more power than expected.