sounds to me it's the alternator. i would take it to an Advance Auto and let them check it for free. also, if you can get the car to run, diconnect the positive battery cable. if the car turns off, it's the alternator because the car should run off of the alternator like it suppose to, after the car is running. if your aleternator is bad, everything is running off of the battery and that's quickly running it down, since the alternator isn't recharging it.