Dell Vostro 3500 battery problems

Oct 9, 2018
I have a 8 year old Vostro 3500. It has a 9 cell battery (3 years old) but now suddenly the battery refuses to charge even with the original power cable. The laptop powers on even without the battery while plugged in. The processor (i3 380m @ 2.53 ghz) never goes beyond 0.88 ghz even under load. This makes even web browsing a pain. I have removed and plugged in the battery but the problem persists. This laptop is a real workhorse for me so some immediate help would be great!