Want the answers to questions about the iPhone? You'll find questions and answers here.
Can you replace a 4s battery?
It can be replaced by Apple. Make an appointment at the Genius Bar. The cost for battery service is US$79. Check prices where you are located.
If you take it to an Apple Genius bar they can test the battery and determine if it really needs replacing, or if there is a different hardware or software problem with your phone.