iPhone 3Gs battery keeps dieing everynight

[siglig]

Hello I bought my iphone refurbished and didn't seem to have any problems at first. Later I realized even when I didn't use my phone the battery would still die out (even having it at %100. it'll still die out within a day). Should I buy a new battery and still it myself? Or could it be some of my phone settings?
If it helps, yes I have my wifi on all the time. I have AT&T with no service right now

 

[danielrmitchell]

Sounds to me that the battery is a tad duff.

Is the iPhone software up to date? 4.3.3

There are many tips both here in the forums and all across the internet that claim to extend the battery life of the iPhone but after following many myself I cannot say that they definitely help.

Have you tried power cycling the battery a few times? Running the battery completely flat then fully charging it for a few hours (beyond the time it takes to display 100%) can help to recalibrate the battery.

 

[awadeee]

Sounds like you need a new battery.