Here's the quote from Porsche N.A. on "Determining Warrantable Battery Situations":

For Porsche vehicles stored for prolonged periods of time, storage conditions defined as follows:
1. Stored in excess of 4 weeks without being driven;
2. Battery maintainer not utilized during this time;
3. Vehicle in question only driven occasionally for short distances over a prolonged period of time wihtout an occasional drive at highway speeds (ie. less than 15 miles/24km per day with no highway driving.

If the above 3 points apply to the vehicle in question, then the charging system of the vehicle cannot properly maintain the charge of the battery and sulfation could set in.

Porsche guidelines on what constitutes reasonable mileage are at least 15 miles/24 km per day or 6,000 miles/9,600 km per rolling 12 months.

Note: Batteries damaged due to storage ie. (sulfated batttery) are not covered under warrantee.

Hopefully, this will clarify things for you. I've just been through this with my car.

 

For those who don't know Phil's driving habits, he has only 2,800 miles on his '04 C4S, which he bought used almost 2 years ago. The battery not covered under warranty because the car wasn't driven enough issue would drive most people to drink! However, in Phil's case, it will drive him to drive.

 

Please Tim, let's not exaggerate. I have 2500 miles on the car, not 2800. And yeah, I have pledged to drive the car this year - especially since it's the only car I own that I can actually get into first gear. The damned new S4 has a faulty synchro and balks at going into first gear - getting replaced next week. The synchro - hopefully, not the entire tranny.

 

I tested the alternator and it sees fine. I appears that it is indeed the battery since the car fires right up after having had the trickle charger hooked up for a couple days now. I believe the battery is bad though since the charger does not seem to be able to top it off and turn itself off (per the instructions) I am now in the hunt for the best battery. After reading several posts I still do not know what to do. I looked on Interstate's web site to find a replacement and they do not show a battery for a 2005 Carrera S, but do for a 2006. I assume it is the same, but when I measure the factory battery in my car it does not match up with the dimensions that interstate claims for the battery. So far I have been unable to find a battery with the same dimensions. It appears to me that there is an additional hole in the battery tray to allow for a larger battery, has anyone used this? I would prefer to keep the same size, or even go smaller to reduce weight, but am not sure what will fit. Any ideas?

 

16 months of possession and 21,000 miles,--no one can accuse me of letting my battery crap out! Please don't tell me that you're trying to avoid driving the car to keep its value up at resale time...the next owner will thank you!

 

That reminds me of the thread you started a while ago (Miles Driven). Maybe you should update it now that we are in MY '08. I ended up putting 22,000+ on my cab in 17 months of ownership - you and I seem to be similar users.

 

Oh please not again! Ow, my head.

 

In case someone needs to know in the future I replaced the stock battery with an Interstate Battery(MTP-91) This is the same battery that 911's have been using for many years. It is smaller than the stock battery and lighter. The battery tray has another treaded hole that allows you to mount a smaller battery, so this one works great. I looked at putting the MTP-93 in it because that is what the Interstate web site suggests for a 2006 Carrera S, but since mine is a 2005 Carrera S I was not sure it would work. Indeed my battery tray does not have a treaded hole that would allow the larger battery to work, so I went with the MTP-91. Problem solved.