Dmann0748

I have an 2004 Audi A6 2.7t I bought a year ago. After some common problems fixed the battery was dead one morning out of nowhere, I've got the original battery and now the voltage stays around 12v but when I have the ac on it sometimes drains the battery gauge below 12v and when and Econ won't turn off ( comes on on its own)i shut car off and when I do the battery is to dead to start the car and have to jump it. Any help would be great!