I don't know what's going on buy my phone tends to lose charge very fast, a full charge doesn't even last a half a day. What can I do about this?
Perhaps you can give us some more details. Are you on the Dev Preview? Did your battery problems happen right after installing the Dev Preview?
Back in January, our friends here at WPCentral wrote an excellent article with battery saving tips for times like this:
17 tips to extend battery life on Windows Phone 8 | Windows Phone Central
But if your battery isn't even lasting
half a day, you probably have a deeper underlying issue going on with your device. I would spend some time going over everything, and consider the possibility of applications or services running unwanted in the background. If you end up at your wits end, it might be time to go ahead and factory reset your device. Something else to consider, and hopefully this isn't the case, is that your battery might simply be crapping out on you. They do go bad, and can only be charged a certain amount of times before they lose their energy.
Anyhoo, I hope you can fix your problem. Report back in later and let us know how you're doing. Your experience may be able to help someone in the future who is having the same problem.
Good luck!