Poor Battery Life

Dear

I am using iPhone 4S from last one year. From last one month the battery

back up I am getting is 4 hrs . I am not using 3G network only 2g . When

the battery % comes to 45% the iPhone immediately goes to off & I have to

recharge. Initially it was working upto 3-4% of battery life.

Really I was fade up due to this poor life.i am using all tips for battery

life improvements still it's problem.

Give me the solution.

Regards

Manoj