The link below will review steps for optimizing the battery life on your iPhone.
If trying these steps does not resolve your issue, a telephone Technical Advisor or Genius at a Retail store can run some diagnostics for you.
Contact Apple Support
Save time by starting your support request online and we’ll connect you to an expert.
U.S. iPhone technical support:
(800) MY-IPHONE (800-694-7466)
Hope this helps ...