I was driving home from work and noticed my battery light flickering on and off. Once I got home I shut it off and started it again. Now the battery light on the cluster is constantly on and the volt gauge reads pretty low (Im pretty sure the stock volt gauge is an idiot light anyway, on and off...right???) The previous owner put the battery in, so I have no clue as to how old it is. I've owend the vehicle for over 2 yrs now. I cleaned the battery terminals REALLY well because there did appear to be some corrosion. So do I need a new battery/alternator, or both?