it could be just the battery or just the alternator or maybe neither..... first you have to start off with a fully charged battery then a test it run on the battery and the alternator....if you dont have any meters just go to an auto zone and let them give you a free test to see if the battery or the alternator is the problem.. might just be that the clamps on the battery cables are tarnished with sulfuric acide buildup(the white residue on the clamps???
or inside the clamps... if you have a meter get the battery charged and see if it holds the charge(where you have it charged then can do a quick charge and test on it to make sure it holds the charge(but if you start off with a low battery then you have trouble making the test.....).....
hope this helps.
