Porsche Cayenne Turbo dieing battery

[formulamd]

Hi All,

I wanted to thank everyone for all the DIY's and other information on this forum. Its been a BIG help!

Anyhow, I have a 2005 Cayenne Turbo which has an electrical issue that will not seem to go away. This issue recently is the battery has been draining intermittently to the point where i let the car sit overnight (10-12 hours) and the battery voltage will go down to 7-8VDC. Other days, I let the car sit for a few days and starts up right away.

What I have done/ recorded.

I have no Durametric codes when this happens, other than the VBAT low threshold on every module which goes away upon charging the battery and resetting the "module codes"

I replaced the battery, one with OEM and bought another one from autozone as a backup, both check out ok. and have been load tested multiple times. (Side note, I do not have the 2nd battery in the trunk)

I will get a battery/generator warning every once in a while upon starting which does go away. I have been logging my battery voltage with the durametric and with a DVM in the cig lighter. When this error happens it seems like the alternator is not charging ( 11.2-11.5VDC) When the warning goes away, my voltage goes to 14.2-14.5VDC and stays there constantly. Upon loads, i.e headlights, radio brake lights etc it drops to 13.8-13.9VDC. This is telling me that my alternator is working and charging the battery.

I did some resistance checks around the v+ battery terminals and cleaned up what was though as a "higher resistance" on the + cable of about 1 ohm. I cleaned the contacts and put star washers on every screw terminal which fixed this issue.

While the battery cable was out, I measured paresitic current draw with the car in "rest/sleep" mode and i only drew 100-150 mA.

One thing i notice is when the car is sitting, in rest. I do hear things under the hood along with my radio cd mechanisim every once in a while move. I know for a fact i am not drawing this current but it will settle down and go quite which will then draw 100-150mA

Sorry for the long winded start of a thread, I am slowly giving up on what could be a matter with this truck and am hoping any of you could point me in a right direction on this issue.

Thanks

[formulamd]

Quick update, With the car in "sleep" About every 10 min, I notice the wipers move a bit. Has anyonce seen these haunting issues haha?

[bigbuzuki]

Time to get the exorcist.....

The fact that your wipers are moving whilst asleep is a clue.

For starters, I would pull the wiper fuse and see if that eliminates your battery issue. It's the 30 amp fuse #8 on the left side dash fuse panel. Provides hot bus power to the wiper motor.

Edited March 25, 2014 by bigbuzuki

[formulamd]

Ok thanks! I will try pulling that and see if the battery drains. I also am going borrow a data logger with a current shunt and let that run overnight to see the current draw over time.

[formulamd]

I got the logger running as the car is sleeping. I pulled the wiper fuse and still have the battery drain condition. The condition seems to be where the drain will draw a constant 5-7 amps for approximately 5-10 mins then return to 150mA. I hear my radio cd mech and navi dvd running. I pulled the radio fuse and so far i have not seen this current draw.

Has anyone seen the radio act this way? I notice that my navigation and map will not get past the splash screen of one bar.

[formulamd]

Update, with the radio fuse pulled, I still get a 2 A peak, therefore my assumptions are that the radio is being woken up. I pulled the KESSY module fuse, of which my current is back where it should be 100-200mA (at least over night).

I have read that the KESSY module can cause all sorts of ruckus. Would it be safe to say that this is the issue? Also will I have to relearn my keys if I try to repair the module? Any input would be greatly appreciated.

[formulamd]

Anybody have any ideas or seen anything like this? I am getting inconsistent current measurements. If i pull the radio and the Kessy fuse i never approach the 2+ amps randomly. Can it be that both modules are bad? Or is the kessy talking to the radio via false CAN messages.

[royxaxa]

I am having the exact problem. also the clock always runs slow. sometimes 30 mins overnight.

I replaced 2 MOSFETs on the kessy board and 6 resistors(you could find a DIY instruction). it seems to be working in the first couple of days and the remote function works in a bigger range and all 4 doors could be unlocked. but the draining battery issue still happens from time to time. the clock seems okay after fix even when battery drained and I have to open the door turning the key.

one thing I notice is that the driver door entry mechanism is little delayed compare to other doors by hearing the unlocking clicks.

I did not have to reprogram the kessy unit and it is really easy access. the 2 MOSFETs were hard to remove. I think it is worth trying by replacing the 2 MOSFETs and 6 resistors. really easy job compare with some others.

hope that helps.