I am currently using a Dell XPS-13 (2019) and I would say I am very happy with its battery life. It can get quite hot after a long session which will cause the battery life to start draining much quicker so usually I will take a break then to let it cool off.
From what I know, to save your battery life without compromising performance, you can:
- Turn off your back-lit keyboard
- Lower down your screen brightness (this is probably obvious but it can really boost your battery life)
- If you have a discrete graphics card, change it to integrated graphics
- Quit applications that you are not using (especially OneDrive)
- Kill unnecessary background processes
Some battery myths I know:
- Keeping it charged all the time is bad
- Charging it when it's 30%-80% is bad (In fact, you would ideally want to keep your laptop running around this percentage to maximize its health. Personally, I just keep it charged as long as possible to reduce its cycle count as much as possible because I don't feel like try-harding lol)