Problem with a laptop battery

Hi, my pc is hp pavilion dv5-1135ee which i bought about 15 months ago.
A couple of days ago i realized a problem with my battery, it doesn't pass 76% while still showing charging (charging forever). When i unplug the charger, the battery last for about an hour or less and shuts down without a warning (like a power cut) without reaching 10% (when i used to get a warning msg). So is it my battery or what's wrong?
Thanks for reading.

Consider replacing the battery

Folks here gave me some very useful advice re my battery problem; problem is not identical to yours but you might wish to have a read - and a very useful related link by Barman/Peb.

http://www.sevenforums.com/hardware...-laptop-but-battery-lasts-less-than-hour.html