Up until about three days ago, my nexus s 4g has been getting about 28 hours per charge with moderate use. However, recently I have suddenly been getting only about 6-7 hours, which is driving me crazy. I have been monitoring my running apps and services via the manage apps screen and nothing new seems to be running and I am only using 120 mb of ram. When I check the battery use menu, it says that display, cell standby and google services are the top three things using the battery. I do not use live backgrounds or turn on 4g. I have been trying to use my phone as little as possible to try to maximize my battery, but it still dies ridiculously quickly. Is there any way I can get my battery life back to where it was before without doing a factory reset? I don't want to lose my app data or root my phone.