when my battery went bad in my old car(1989 Dodge Aries LE
)I took it to autozone or advance auto parts I cant remember, and they tested it, but first me and my dad thought it was my starter(which was part of the problem it was going bad but thats a whole different story)and I got it tested and got a new one and it worked just fine, so I'd say take either(battery or alternator)to a auto parts store and have them test both, if they do the tests that is(btw its free)but if your battery isnt keeping its charge after you jump it its gotta be either alternator or both.
