1996 Chrysler Sebring Battery or Altenator

Recently my car was dying when I would pull up to a redlight or stop but I could give it gas and it would stay running it only did that twice and I didnt have any more problems with it but the other morning battery died overnight and I am not sure what the cause of it was I finally got someone to boost me off and got it to crank after that I drove around for a few minutes and then come back home and parked it and when I turned it off it wouldnt crank back up I am thinking that it was just that I didnt leave it running long enough for the battery to get a charge or the battery is just bad I hope that is all it is do you think it could be the altenator