It really helps people to help you if you give a bit more information when asking questions, especially if you want an answer.
For example are you talking about a phone, or maybe a tablet, if a phone what make, Lumia, HTC, there are several makers of phones that use the Windows Phone OS, what model would come in handy as the battery life on different models can be very different.
How long are you getting, ten minutes, ten hours, ten days.
Even then, there are so many variables, like your settings, usage etc.
Bob