Battery draining way, way too fast (ASUS pc)

Hiya!

Now, I'm aware that with Windows 11 the battery doesn't exactly have the same life as with Windows 10. I have made peace with that.

However, a few minutes ago I opened my pc, which had been shut off since yesterday, and was fully charged. I SAW the battery at 100%. By the time I reached YouTube the computer had shut down. No battery. The whole operation might have taken one minute if I was going slowly. 

I remember this happening once or twice before, so it's not a regular occurrence, but I would like to know if there is a way to solve this since when I'm at Uni I don't always have power sockets close to my seat.

Thanks 🙂