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Battery dead... again! 3rd battery lasted 17 days


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I have a 2004 cayenne S with 56,000 miles. drive it almost everyday to work and back. 7 miles... each way.

i have had the water pipes done and then the transmission seals. 45,000 miles

other than that no problems.

in July 2011 put in new batter.

i dec. 2011 put in another new battery.

on march 22 the Dec. battery died.

quick jump start and took to dealer.

tested and dealer said bad battery - not porsche quality.

about 3 weeks later porsche battery dead.

so. jump start and off to dealer. at dealer battery just had enough juice to start the car. so charging system is working as it was only 10 miles to dealer. ran A/C on the way. Amp meter shows 14amp charge and all electrical worked fine once the car was running.

any ideas???

i after reading other reports, i remved the bose sub from where the spare tire would be an there is not a second battery. i am 100% positive of this.

thanks for any ideas or suggestions.

thanks, Michael

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Michael,

The "amp" meter is a volt meter.. but 14 Volts shows the alternator is doing something. Sounds like you have a parasitic load drawing current when the vehicle is off.

Have you added any electronics to the car? If not - it requires some electrical experience to track down this sort of "leak".. and a DC ammeter.

Cliff notes: the ammeter is connected in series with the battery and the positive cable. The car is allowed to go into "rest" mode (not sure how long that takes on a Cayenne, BMW's are 15 minutes.) Rest mode is when all the modules basically go to sleep and stop listening to each other. Once that happens - and ALL lights are off - you can expect to see a constant draw of perhaps 100mA to 200mA. More then that will pull the battery down if the vehicle isn't used regularly. To track down what is causing the draw-down, you start pulling fuses, one at a time. When you pull one that drops the current draw down to the expected rest-state - you've got a big clue as to what is causing the problem... it's what is connected to that fuse.

Cautions - do not turn the ignition on with the ammeter connected - have the key OUT of the car. Turn all lights off (interior especially - people often forget this.) Do NOT try starting the car with the ammeter in the circuit (you'll blow up the ammeter.)

If you don't have the skill or patience to do this (and it can be time consuming) - take it to someone who knows what needs doing and pay them to do it.

If you've added any electronics to the vehicle - disconnect them as a first try. Sometimes aftermarket stuff does things like this.

BTW - I noticed the vehicle gets 7 mile trips quite often. It is entirely possible you aren't running the vehicle long enough after starting it to restore the power used to start it.. that can eventually discharge a battery. Perhaps you could take the long way home?

Edited by deilenberger
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The Cayenne is a difficult vehicle to trace battery drains due to the complex convenience systems. You can no longer "start pulling fuses" to locate the source of the drain but you need to open both front doors,trips the latch mechanisms, remove the ignition key away from the vehicle and let the vehicle rest in this state a min of 20 minutes.

One then measures the voltage drop across the fuse and using a cross-reference chart and the fuse rating to determine the allowed milliamps parasitic draw of that fused circuit. You need experience,patience and a good quality DVOM.

Before going through fault tracing a battery drain be sure the charging system is operating correctly. Even though you have have 14 Volts that does not mean your are producing enough Amps. There is also a ground connection located under the drivers seat which can become loose or corroded.

Can you hear anything running after the key is off? The cooling fan control module or coolant temp sensor can fail causing the cooling fans to remain on after the key is removed which can quickly drain a battery. Any other electrical problems noticed?

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thanks for the updates. Porsche put in the battery so i am hoping they got it right. i cross checked the first 2 after market and they were correct.

the car is garaged all the time and i do not hear any fans or pumps running. I am going to let porsche take a look at it. they dropped the ball last time by just throwing a new battery in it... so we shall see...

i did all the basic stuff... and check the connections in the battery box.. all tight.

and car is 100% factory original...

thanks and if anyone has any ideas... thank you in advance for sharing!

michael

Edited by woodslayer
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Plug-in a CTEK when you park overnight -- see if it makes a difference. Do it for a week or so. The point deilenberger makes about about your short trips is a good one. Over time, you simply may not be giving the battery enough run-time charge.

CTEK is an OEM for Porsche. I use the model 3300 in my '04 Cayenne S, single battery. (I bought the cigarette lighter plug attachment so I don't need to pop the hood to charge.)

http://smartercharger.com/battery-chargers/#CTEK%20Multi%20US%203300

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I would like to think you can still do a traditional amp draw check on your battery. Get in the car and disconnect the negative on the battery and hook up your volt meter. Set to amps. Don't forget to get your radio code. Because a battery only lasted 17 days I bet you are only looking at a very small draw. Maybe .5 amps? Once you confirm you have a draw the next step is to find out what circuit. You could start pulling fuses to isolate it. Then when you find the one you will need the wiring diagram to see all that is running through that fuse. Or better yet use the DMM as described above.

Modern fuses are great. There is a cutout on the top of them making it easy to touch leads from a volt meter without having to remove them.

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I would like to think you can still do a traditional amp draw check on your battery. Get in the car and disconnect the negative on the battery and hook up your volt meter. Set to amps. Don't forget to get your radio code. Because a battery only lasted 17 days I bet you are only looking at a very small draw. Maybe .5 amps? Once you confirm you have a draw the next step is to find out what circuit. You could start pulling fuses to isolate it. Then when you find the one you will need the wiring diagram to see all that is running through that fuse. Or better yet use the DMM as described above.

Modern fuses are great. There is a cutout on the top of them making it easy to touch leads from a volt meter without having to remove them.

It will only lead to inaccurate readings. There is a very specific way to diagnose battery drains on these vehicles that Porsche provides for a reason.

  • Upvote 1
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Resolved... So the negative ground from the battery to car had a little corosion hidden at the bolt and between the terminal and the frame. ran the car with all the electronics on and fan and lights and radio... found the ground strap getting warm and problem solved...

thanks for all the help.

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  • 2 weeks later...

One more thing to consider. We had an 04 Touareg that kept running down the battery (and had various other electronic glitches) and the problem ended up being, as I recall, either the KESSY (keyless entry) system or some other controller (there was also an issue with the steering angle sesnsor being shot). In any case, the net effect was that the car's computer systems would not "go to sleep" after the car was shut off and the battery kept running down as a result. The excellent service folks (talk to Fred) at Ed Carroll Porsche/VW in Fort Collins, CO tracked it down and fixed it.

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  • 4 years later...
On 4/16/2012 at 9:54 AM, wvicary said:

The Cayenne is a difficult vehicle to trace battery drains due to the complex convenience systems. You can no longer "start pulling fuses" to locate the source of the drain but you need to open both front doors,trips the latch mechanisms, remove the ignition key away from the vehicle and let the vehicle rest in this state a min of 20 minutes.

One then measures the voltage drop across the fuse and using a cross-reference chart and the fuse rating to determine the allowed milliamps parasitic draw of that fused circuit. You need experience,patience and a good quality DVOM.

Before going through fault tracing a battery drain be sure the charging system is operating correctly. Even though you have have 14 Volts that does not mean your are producing enough Amps. There is also a ground connection located under the drivers seat which can become loose or corroded.

Can you hear anything running after the key is off? The cooling fan control module or coolant temp sensor can fail causing the cooling fans to remain on after the key is removed which can quickly drain a battery. Any other electrical problems noticed?

hello, i wanted to know where i can get this cross reference chart you mentioned and how do i know the allowed draw of each circuit?

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