Checking the health of my iPhone's battery It seems that my iPhone's (4s - purchased Nov. 2011) battery loses its charge fast. 

I have read all the relevant OPs. Is there any app which provides information about the battery's health? Or should I simply change it?
the current os does not seem to show this data or at least not as described above.
This is an excellent app which tracks battery health for both the laptop and iPhone.

Free - 
http://www.coconut-flavour.com/coconutbattery/