Mike_k

I get the feeling nobody is going to really know the answer here but I'll throw it out to the community before I start chasing it down. 2007 S8, new battery. Battery goes dead after a few days. The only thing I've noticed with the car is that there is a constant clicking of a relay once every 5 or so seconds. Doesn't matter if it's locked, unlocked, key near it or away. It's always clicking near the battery. Is there a system here that would remain active for some reason?

MP4.2+6.0

Well, IIRC the power management system is right there for starters. It could be a symptom rather than the issue. You need to get a quality scan and look for any devices malfunctioning or not going into sleep mode. Also should run a scan for the optical loop looking for same. Need a quality scan tool in turn, not OBDII generic like the parts counter loaners.

Short of a good scan tool that can reach all the car's modules, if your car has any, be suspicious of add on devices that were spliced in--cameras, add on players, etc.