Acer Aspire 4820TG battery zero backup

[Oblit]

Acer Aspire 4820TG battery suddenly stopped giving any backup, not even one second. The computer crashes the moment I remove AC adapter and when I turn on the computer again the battery charge level is still what it was before crashing. Very recently the battery used to give 2 hours backup.

Also, in Windows it says 'plugged in, charging' but the battery is slowly discharging, losing around 1% charge everyday. I think this is normal discharge rate for unused battery but I am puzzled why it is not being used to provide backup.

I tried removing battery and adapter and pushing power button for 1 minute. Did not work.
I also updated BIOS from Acer website. Did not work.

 

[Phillip Corcoran]

If you've been using your laptop from mains power for long periods with battery attached, the battery may have suffered premature failure. It isn't correct to think of it as a "backup" battery, it's just an alternative power source. To keep it healthy and prolong it's useful life, you are supposed to remove it from the laptop during long periods of running your laptop on mains power.

I imagine the battery needs replacing now.

My laptop battery shows the same symptoms of having been abused in a previous life (I bought the laptop second-hand).