I've gone through so many batteries with my 996tt. It used to be that if I didn't drive it for a couple weeks, the battery would die. I was able to tolerate that. But now, if the car sits for more than a day, it won't start up. I've checked all the electronics and lights. Even stranger is that if I take the dead battery to Pepboys (where I bought it), their tests determine that the battery is completely gone and can not be recharged. The only bright side is, they let me replace it free since they have a warranty on all batteries.

Any idea what could be causing this?

 

Typical P-car issue. Try the Optima Blue top. Costco has them for around $160.

 

are you able to put a trickle charger on the car a battery tender?

this would fix your issue

 

+1 you need a maintainer

 

I have a maintainer, but it's unrealistic to use it every time the car is parked in the garage or elsewhere. In the past, I would use it during the winter or long breaks, but now I can't even go one day without the battery dieing. Even if I drive the car everyday, it still struggles a bit to get started initially.

A few days or weeks without driving, I can understand there being some issue starting, but just 24 hours?? Seems really strange. If this is common, how do dealerships get the cars on the lot to start up?

 

dieing that fast is uncommon you have something draining the battery forsure.

my car sits all week long and starts right up on sunday to drive.

do you have any aftermarket wiring done to the car?

 

I've noticed with these cars that you ALWAYS ALWAYS ALWAYS have to set the alarm and put it to sleep. I have what can only be descibed as a motorcycle battery and I never have issues. I never remember to plug in my maintainer either and my car has sat for weeks, with my little battery and starts right up. I set my alarm all the time and it is inside nice and warm.

 

didn't know there was a way to put er to sleep =) my alarm has an open circuit always chirps and dont have issues with a stock battery no idea of which brand.

 

Yes, seems like a common issue but I also had a tender hardwired...but would be hard to do if you don't park a personal garage

 

One the battery has been damaged, and struggles to maintain a charge for "just overnight" then a maintainer does no good.... The maintainer is to prevent the inital damage, not to fix the problem once it is done.

Of course addressing the battery drain issue is the first step. I never lock mine, so no issues for me...

 

I am not sure why nobody has mentioned this, have you checked your alternator? what is the voltage on the posts (do not use the inside gauge). Second, have the battery checked to see if it charges to the min of 80% and holds. this is usually a free service offered by any Sears or Pep boys.

All fails, you can check for excess current draw when car off. I am sure someone with better knowledge of Porsche (or a service manual) can provide that approximate current draw. Then given the capacity of your battery in AH, we can figure out if this is a battery issue or otherwise.

BTW, does anyone know the difference between red top and blue top Optima specs?

 

Tt boost , i heard some one else say that about setting the alarm on the car to help with that issue ... do you know why ? i never set my alarm on the car since its parked inside at room temp and lately if i dont drive the car for more then 5 days or so i struglles to turn over.

 

Arming the factory alarm: After 3 days the car will go to "sleep". No electrical current. The keyless entry doesn't even work. Then you have to open the door with a key and all is well and alive again.

 

anikzad, thanks for the response. I don't think it's an alternator issue since I've taken the dead batteries to Pepboys for testing and each time the battery turns out to be unrepairable. In other words, something on the car is slowly draining and damaging the batteries.

I don't have any aftermarket electronics except for a radar detector which I unplug when the car is off.

 

Yes, mine sits in my nice warm basement too. Todd is correct. Also, I should clarify that if my car sits for WEEKS, without setting the alarm, I will get a hard start, but it DOES start. To be fair, I haven't done that with my little battery, but likely might not start with the little battery.