My a6 wont crank. when I turn the key I hear a hum from the trunk but nothing else. I charged the battery overnight and the charger went to the green light. Tried to start with same result, nothing. The lights come on but not the mmi or radio. No horn. I hooked the charger up to the terminal under the hood and now I get a clicking noise but still no crank. It is a 45 mile tow to a shop. Is there anything I can do to prevent this? If I pull the battery should I take it to a parts store to get tested? Should I only buy an Audi Battery?
Thanks for your help!

 

Fast clicking noise is usually the classical sign of a failed battery (or undercharged). Since you charged it over night and get nothing the next morning - the battery probably can't hold a charge. Take it out, get it tested.
Personally I always install a Bosch Battery (OEM) for my Audi's but I've successfully installed Autozone and Walmart batteries in other Audi's without issues (might not last as long or might have less CCA - which could give you issues on very cold days).

 

Thanks Sheldon! I bought an Autozone battery. It doesn't get real cold here in central south Texas very often, so i hope it will last. I found out I may have to take the car in now to get the computer reset. Well at least it won't have to be towed!