tkerrmd

Ok, everytime I leave the cay alone for over 5 days it takes revenge by the battery dying. It did this after I had it for only 6 months and anytime thereafter if sits for more than 5 days without a charger. Dealer says, "well lots of computers and stuff drain the battery". WTF? I have cars sit in my garage for months without a charger (mercedes) and ALWAYS start right up!
At this point cant take the cay on any airport trips where I will be gone more than 5 days or battery is dead. Dealer says nothing wrong and new battery wont help?
Any suggestions?

tom

PS.....I love this damn truck!! (sorry Lewis )

wingless

A Midtronics Battery Tester is the tool to quantify the battery condition. It will define the state of charge and the battery capacity. This will permit an accurate judgement of the battery health.

The "dark current" may be measured using a multimeter. The limits are defined in the shop manual, based upon the vehicle equipment.

The charger output and components may also be measured and compared to standards.

Battery problems suck, but may be resolved using normal analysis and by following procedures.

wingless

There have been a rash of failures for alternators on the '04. This could contribute to battery failures, as they degrade when not maintained fully charged.

Fortunately, the alternator has been redesigned, again, which may reduce future failures.

tbill

Tom: I also have an 2004 Cayenne. I've have it stored in a warehouse for over two weeks from time to time and never had a problem like this. May be like wingless stated it's a bad alternator thing. Maybe take to a different Porsche service center and see what they come up with. My SL 500 sits in the garage most all of the winter and as you say cranks over 1st time.
Tony

skl

OT, Tom, I'm going to be in the Tampa area over the next weekend visiting relatives, is the car show at Vinoy Park worth going to??

(BTW, mine is a '04 and it doesn't do that either...)

Chriz

Huh nothing wrong? If you cant leave your car for more than 5 days there is definately a problem. Maybe you have the wrong dealer. If he cant fix it try another one.

MadFox

Our forum has finesse. We usually intimate throught sarcasm what is the problem with our forum brothers. I think being direct is actually counter-productive except in certain situations. I have had my vehicle at the airport for 10 days on several occasions. Subtle, humor, sarcasm, and deep thought is necessary in this circumstance. Not.
YOUR DEALER IS A LIAR!
Other than that I have no strong opinion. "I feel good" --- dah na na na... where's james brown when you need him?

phaedrus242

I would set the battery up on a very low amp charge overnight and try to get the battery back up to full capacity. A battery that sits will sulfate and thereby reduce it effectiveness at holding a charge. Oftentimes these batteries will pass a load test and even carry a decent surface charge. The alternator on your vehicle was not designed to "charge" the battery per say, rather to maintain a consistent voltage levels. While a longer trip will definitely charge up the battery, short trips will serve to only further drain it. If after a couple nights charging at 2 amps or so the situation does not improve, I would begin checking for (or having the dealer check) for a parasitic draw in the system. After all the computers go to sleep (this can take a while), an ammeter installed in line with the battery (an inductive clamp is not accurate enough for this purpose) should read between 20-30 mAmps. If the number is higher than this, there is a draw and that is why your battery is dying. While these vehicles aren't great at sitting idle, five days is not adequate. I believe Porsche's official recommendation is that if the vehicle will sit idle for more than a week, a battery tender should be used. This is still for the long term benefit of the battery, not to say that it should be dead in a week. From my experiences, a fully charged battery in good condition will give you about 3 weeks or so of sitting.

ltc

Hi Tom,
As wingless pointed out, tracing down a 'dark current' problem requires an ammeter installed in series (or clamp on type if you want to get fancy) with the battery + and then an entire set of tools to begin disassembling the Cayenne, unplugging each "computer" one at a time to find out who is drawing more 'dark' current' than originally designed/specified.

(BTW every OEM supplier to PAG has a 'dark current' specification for their "computer"....for the Bose DSP amplifier, I've heard rumours that it is something like 250microamperes or less (250 millionths of an ampere....but how would I know for sure )

The reason your dealer is reluctant to try and track it down is simply the inconvenience/time of removing trim panels, dashboards, radios, putting the car up on the lift to find/unplug these "computers" one at a time. Then once he finds the defective "computer", he has to order a new one, then since it's a much newer rev than the one it's replacing, have to figure out with PCNA Tech in Atlanta how many other "computers" need to have updated S/W installed via PIWIS.

If it's not a "computer", then they will also likely check the alternator for reverse leakage current.

I'm not going to ask if you are under warranty or naked..........

I love my Cayenne too, it's just a different kind of love I suppose.

ltc

I own one that has 0.1mA resolution, perfect for jobs like this......but I have no idea why I own it.

wingless

It would be acceptable to measure the total dark current and compare that to the acceptable range for the vehicle with the configured options, instead of each individual user.

It is my guess that the alternator is not up to snuff. If so, then the battery may now have diminished capacity, due to not being maintained at a fully charged condition.

Testing will reveal the source of the problem.

MadFox

As Ed McMahon would say, "You are correct, SIR!" However, this is all schitzu that you should NOT have to do if you are still under warranty (if you're naked, then wade in) but, again, that is why I stated your dealer sucks and..........
Your dealer is a LIAR! --- but, I digress do we do that on this forum?

Do you have another dealer close by? IF you do, I would take it over there and then bill the difference in your time and miles to your current dealer. Yes, I know that is like hmmmmm.. what did one guy on this forum say... like pissing on their heads? But, you get my drift.. they're jerks. They are not focused on customer service. Not being focused on customer service is BAD... yes a BAD BAD dealer.. "he's BAD .. she's BAD.. who's BAD".. bee pop.. dun na na... where's Michael Jackson when you need him...... er, scratch that (no pun intended) no MJ ever needed..

MadFox

Because you're "psycho" and a perfectionist dang engineer... damn every time you get off the meds.. you babble... Nurse Ratchett... 500 milliamps on the paddle ... STAND BY... CLEAR..
Feel more like your old self... ornery and sarcastic.. this nice guy schitzu sucks.

mudman2

Tom

A few 04's had similar issues but I have not heard of any lately. There were some bad batteries that were replaced, I seem to think Torags also had a problem but he had finger trouble.

Another was a rear hatch issue wear water was leaking into the electrics.

Then as Madfox says a few alternators were iffy.

Tom you had this in September 04 also, here is Toby's reply from then.....

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

Wow, got to admit, there are alot of smart well read guys on this forum and a great way to get good info. I appreciate all of your inputs I learned alot!!
My overall take is I'm going back to the dealer and put it in his court.......Lewis my odometer just turned 50k today.....I am offically naked!! So I guess this will be some huge repair bill!!!

thanks again to everyone, very helpful.

skl.....Nice car show and VERY nice area/shopping/stores/food, ect.....Let me know if I can be of any help when you are down here!! My cell is 813-731-7493 or e-mail....tkerrmd@aol.com