I recently bought a 2000 a6 with a few mods and a tune, the car apparently seems to have a parasitic drain after the battery and alternator was replaced. After a bit of research im still rather clueless on this as nothing is malfunctioning electronics wise, there is no check engine on but what i did notice is the volt gauge dips down below 12 volts and the car likes to randomly try to die while driving. I suspect is might be a bad ground or the alternator isn't charging the battery. Could the fact that the battery is smaller than the original battery be the problem? It's a 2.7t 6spd. Thank you for the assistance.