Yesterday I was on my laptop and everything was OK. And today I started my laptop and I signed into Windows and after few seconds screen went black and I heard the Windows notification noise (I hear it everytime I am on my laptop) and then the laptop turned off. Also the laptop is older and 3 or 4 days ago when it starts up it shows a text saying that the battery capacity level is very low and that I should replace it. Is it because of the battery ?
My laptop: HP Probook 4520s
Well it has to be plugged in the wall because the battery capacity level is very low.
Had to ask because there are some problems, such as voltage regulation, that could also cause a laptop to power off while reporting power issues. If it works normally when plugged into a wall it's likely the battery at fault. Technically, it could also be something wrong with the laptops charging circuitry or the power adapter causing the battery to not charge. But, the chances of that are fairly slim, and the chances of an old battery no longer holding a charge are very high. Most laptops have some software included to check the health of their battery now, or you can download a free utility to double check.