Battery - unplugged shuts down after few minutes

Question

I have had this computer a little over a year and recently when I unplug it, I can only use it for a few minutes. It shuts down.....I checked the setting (so I think) but can't find anything that I can change.
Any ideas? Do I need a new battery?
Here are the specifics....
System Power Settings:
AC Power:
System Sleep Timer (Minutes): 15
Disk Sleep Timer (Minutes): 10
Display Sleep Timer (Minutes): 15
Automatic Restart On Power Loss: No
Wake On AC Change: No
Wake On Clamshell Open: Yes
Wake On LAN: Yes
Display Sleep Uses Dim: Yes
Battery Power:
System Sleep Timer (Minutes): 5
Disk Sleep Timer (Minutes): 180
Display Sleep Timer (Minutes): 5
Wake On AC Change: No
Wake On Clamshell Open: Yes
Display Sleep Uses Dim: Yes
Reduce Brightness: Yes
Battery Information:
Battery Installed: Yes
First low level warning: No
Full Charge Capacity (mAh): 2152
Remaining Capacity (mAh): 2071
Amperage (mA): 0
Voltage (mV): 12344
Cycle Count: 90
AC Charger Information:
Connected: Yes
Charging: No
Hardware Configuration:
UPS Installed: No

Answer 1

Check this article:
http://www.apple.com/support/macbook_macbookpro/batteryupdate/