With phones such as this, you can significantly improve the battery life by turning OFF the Bluetooth antenna, which is often set ON by default.
In reality, how often do you need your bluetooth antenna on? Even if it is several times a day, turning it on manually is easy, and safer to boot!
Also, even with brand new phones, it is a good idea to download the latest version of the operating system for that phone. Often there are fixes that improve the efficiency of installed programs, thereby improving battery life.