PogueMoHone

I park my car for 24 hours, go back and the battery is dead.

Prior to parking it I just had the Sirius radio hooked up (very impressive) and I'm wondering if I could have inadvertently left it on and caused the battery to drain (so rapid!) or should I be looking for another cause?. If so this would surprise me because I thought everything automatically switched off.

Suggestions or experiences appreciated.

TIA

mudman2

more likely you hit the turn signal lever when you got out and switched the parking light on.

Truble10

Something is wrong. I parked my CS and 996 TT since April and had nothing done to the battery and both fired right up five months later.

jamy85

same here had my car parked for 3 months and it started up fine

Jeffrey Behr

Mine has had 2 dead batteries in a year, for no apparent reason. Overnite in my garage, the 1st time the dattery was QUITE dead. The 2nd time, it was too low to crank the engine.

Both times I had to remove the center console* to move the car so I could jump it--my garage has an overhood cabinet--and both times my dealer could not find any fault.

The car has a complex computer system, and altho Micro$oft apparently had nothing to do with it, the system still 'tilts' occasionally.


* which is a story unto itself. This process is in the owner's manual; if anyone wants more info, let me know and I'll dig it out.

Toby Pennycuff

Colm,

The system shuts down in stages. The Service Information Technik manual provides a good description of how the system works. Here's what it says on page 9.2 and 9.5. Did you get any "Low Battery" warnings before things went dead? This happened to me a few months ago, and it was simply a bad battery. I got the low battery warning twice and went in for the Service boys to look it over. They determined that the battery was headed south fast and that it was a good thing I had brought it in. Apparently, the electrical draw of all of the various control units is so much that once the battery starts downhill, it goes really fast.

Get someone to read out the OBD-II codes and see what the system thinks is going on. Hope the following info is helpful in understanding how the electrical system works.....

Toby


"Battery
"A battery under the driver's seat supplies the voltage. Since there are fewer variations in termperature, this location provides more stable performance than batteries mounted in the engine compartment. In the event of an accident, a safety switch (integrated into the primary battery relay in the distributor) disconnects the battery from the vehicle electrical system. In an emergency, the connection can be re-established via a push-button switch on the relay.

"Battery capacity for the Cayenne S and Turbo ranges from 450A/95 AH (standard) up to 550A/110 AH (Cayenne Turbo with parking heater and multimedia options).

"The generator is water-cooled and has a nominal ouput of 2660 watts, corresponding to a maximum current of 220A.


"Electrical Control System Module
"The electrical system control module functions primarily to protect the battery against cyclical overcharging. A large quantity of input data is managed by the electrical system control module, since electrical system management controls driver-related functions and system integrity must always be maintained. Electrical system status is determined primarily by comparing the measured voltage witrh the permissible voltage lower limit.

"The electrical system status is determined by battery voiltage parameters and data from heavy current loads of short duration.

"In addition, the current control states of systems used by the driver are stoed in the electrical system control module.

"The electrical system control module communicates with the DME to provide an increase of idle speed if required to improve the electrical system status. If the system status is negative, convenience-related electrically powered units can be switched off, as required. The voltage thus gained can be then channeled to other control devices via the CAN-Bus. Before such units are cut off (e.g. cigarette lighter, etc) the driver receives a "Battery Low" warning signal. Once the system status is no longer critical, the units are switched on in reverse order that they were shut off. Diagnosis of the electrical system is performed using the Porsche System Tester 2."

tkerrmd

mine died after a week of non use due to the light on the cig lighter!

PogueMoHone

No warnings of any kind..it's dead til Monday

Torags

I had a dead battery last week & needed to jump it. I got careless and left the 5th door open.

Now I'm very careful, cause I'm told the alternator doesn't fully charge the battery. If that is true, then it's possible the battery slowly drains over time (depending on use ). I'm going to ask Dealer fully charge it at oil change.

But I then had a "replace key battery alert" after the 3-4th start. I've had this alert months ago, Once.

Anybody else have it?

Jeffrey Behr

Do you have a Toureg or a Cayenne?

The Cayenne has a HIGH-output alternator that's WATER-COOLED!!!!!!!!! If ANYTHING can charge a battery, it's the Cayenne's alternator.

Torags

Hi Jeff ... good to see you posting again.

I have the S for over a year now. How's your TT.

Jeffrey Behr

Oh I've been reading but haven't been writing much. (Have suffered a recurrence this summer of the dreaded chronic-but-sometimes-acute-disease audiofoolia, so have been paying attention to my multichannel-audio/home-theater system.)

The C-T is as good as ever, which is EXCELLENT. Has 23,000 miles on it. Will be bouncing about in it on a fall-colors foto trip to w. Utah next month.

Torags

Look forward to seeing some posted pics.....

Cay-ute

Colm, the same issue occurs with my S since I had XM installed. I have the two battery version. I have a switch that allows me to cut off power to the XM receiver, however, if I forget to turn it off, the primary battery goes dead in about 36-48 hours. When this happens I turn the key all the way to the left for about 3 seconds then I can start the car. I have not seen an explanation of how this works but it has worked about a dozen times. When the primary batter goes dead, all of the computer settings, including the clock go away, after driving for about 15 minutes, all of the settings return, even the clock begins displaying the correct time. Not sure if this is engineering or magic, either way, that how it works on my S. Good Luck!!

ozr

Your installer probably connected Sirius radio for power to a CONSTANT power source (for example, cigarette lighter circuit, which stays ON even after you shut the car down and lock it), you need to connect Sirius radio for power to a SWITCHED POWER source (switched power is shutdown after you remove the key from ignition).

For switched power use fuze 48 free socket on the right side of the car front panel by the front right door.