I Have A 2000 Audi A6 2.7 turbo Quattro The Alternator Died So I replaced it Got a new one the starter is good and Also replaced the battery with a new one as well. i only had the car for 4 days and the batter started to die From 16V to 6V any idea what could B wrong Isn't the alternator suppose to charge the battery could there b another reason for this problem?