alland

Returned home after being away for 2 weeks and discovered that the cayenne's battery was completely discharged. No problelm just put the battery charger on and situation should be remedied. Not so... when I hooked up my charger (on the 11 amp setting) all the electronic systems in the car go wonky. The headlights randomly go on and off, sometime blinking from side to side, the nav screen attempts to come on in a distorted staticy way, and warning lights blink on and off. I disconnected the charger after a few minutes as things were not stabilizing. Anyone have any idea what would cause this or potential solutions?

DUTCH Vanatlanta

11 amps is a lot to throw at a battery with the rest of the car's system connected. My guess is that it took some pretty high voltage to push 11 amps through; and you may have fried something in the process.

I'll never go above 13.6 volts and 3-4 amps with my battery connected to the car. If I want to push it higher or faster, I'll disconnect the battery from the system

ltc

I would disagree.

Porsche requires that all OEMs who design modules connected to the vehicle battery bus be able to withstand overvoltages without damage (short of a vehicle fuse blowing perhaps, although that is strongly discouraged).
The main types of overvoltage are 24V "double battery jump start"...usually a 2 minute applied test and a load dump test, where the voltage can go up to 60VDC for a few milliseconds, then ramp quickly back down to 'normal' levels.
(as a side note, there is also central vehicle battery bus protection as well, although each module is still required to be designed to protect against these 2 above conditions...as well as others).

That having been said (and not wishing to relive the past...I hate digging up Larry), what you are likely experiencing is a faulty battery, nothing more.
The battery has an internal short (or perhaps more) and likely has low electrolyte levels.
The battery can not maintain a stable voltage (over 10.8VDC), so the various modules behave as you observe.

I'd be willing to bet that a new battery (or having your battery properly conditioned and checked), along with perhaps replacing a fuse or two (check them all), will restore your Cayenne to "normal".

Then again, I could be wrong...what do I know anyways, I never owned a Cayenne.

Dennis C

Cayennes don't do well with a low battery. A new battery, check a few fuses as ltc said and perhaps a trip to your dealer if the systems don't properly reset, and you should be fine. The last time my battery went totally dead, I ended up in this situation: