Gateway T-Series W350i reset battery

Hello,


I have a Gateway T-Series W350i, I have been using it for about 8 Months. It had working perectly alright. I had even Installed Win 7 on it work perfect. The problem is that for last few day my Battery is giving problems. Untillabout 2 weeks back the Battery gave a Backup of around 2hours 15 Minutes but now Suddenly it has dropped down to 50 minutes Maximum. Can any1 help me with this. May if some1 can tell me how to reset the Battery, I've heard that work in some cases. Please Help......