Strange battery behavior

[another_user]

I bought a new battery for my Lenovo laptop almost exactly a year ago because the old one was pretty much at the end after 5 years. Recently, the new battery has been behaving strangely.
On most days, it lasts 6-8 hours on battery power, most of that with Office applications such as Excel and Outlook.
And then there are days when the battery drops from 100% to under 20% within a few minutes of booting up and then to 0 relatively quickly.
I have no idea why this happens and, more importantly, why it returns to normal the next day.
Has anyone ever observed something like this and knows exactly what causes it? (Apart from the fact that the battery is very probably faulty)

[SImoHayha]

the battery is dead/faulty.  Most batteries online aren't "new new" they're mostly used. You probably just need another one unfortunately

[another_user]

Thank you, I will do that. But what interests me is how this happens from one moment to the next. Is there a way to recognize something like this early on, i.e. that the battery will probably not work for much longer?

[SImoHayha]

On 1/16/2024 at 10:13 AM, another_user said:

Thank you, I will do that. But what interests me is how this happens from one moment to the next. Is there a way to recognize something like this early on, i.e. that the battery will probably not work for much longer?

you could use a software called battery-mon to check the "total" battery size. Overtime the limit/capacity goes down