How old is your battery? Typical batteries only last about 2-4 years before they start dying. As for your alternator, if you want to see if it's charging properly, go to an auto parts store and have them test it. Or, just do the ghetto check and start the car, then pull the negative battery lead off. If the engine keeps running nomrally, your alternator is fine. If it stalls and dies, start looking into a new alternator.