Looking to see if anyone has any ideas here. I have a 2012 C2S 991, about a year old, roughly 7K miles. Drove her this week with no issues, but when I went into the garage this am, battery was fully discharged. Absolutely no indications as to why --- nothing was left on, doors were closed, etc etc. Any thoughts? I'm now working through the process of opening the frunk lid to access the battery -- another story for another post.

Curious about the power drain though....any ideas welcome....

 

You didn't leave the key in the car? It will keep the car systems awake.

 

Yeah, always take the key OUT of the ignition. I got TWO dead batteries doing this. Dementia is setting in at 70 !!

 

oem battery?
do you leave the alarm on or off at night? the battery is continuously used and more so if the alarm is not set; a tickler helps

 

I have heard that if you leave the car unused for a week or so, you might end up with a dead battery. However, it seems this is not the case with you as you did use it. As I do not drive mine every day, I use a battery tender.

 

Thanks guys. This one is a mystery. Key was not in the car, the car was locked, nothing left on. Last used the car the day before with no issues. Original OEM battery. I used the Porsche branded battery tender during the winter months when I had her stored undercover for a few months, but she roared back to life with no issues when the cover came off in April.

Scratching my head....

 

when i travel my 991 c2s often sits for more than a week unused. upon first start i get a message in the display that "battery power save mode was enabled due to inactivity" so it seems that the days of dead batteries if not driven for a week or two are gone?

 

You may have a defective battery or something else is going on - my experience with my 991 (14,000 miles & 14 months old) is that I cane leave it for 2 or three weeks and never have a problem, nor have I ever seen the "battery power save mode." I do leave it locked when I am not driving it for extended periods. Don't think my experience unusual.

 

Sorry; time for a trip to the dealer.

ChuckJ

 

first recharge the battery, then test it w/ the engine on and off. It should be about 14Volts.

 

14 volts with the engine running.

ChuckJ

 

so the car is charging the battery. If it happens again, i would just change the battery. $100 or so DIY. Just make sure its similar CCA. I bought mine at Walmarts for the 997. Good luck.

 

You guys get 14 volts with engine running? The most I have ever seen is 13.5.

 

For some reason the charging rate jumps to 14.3v whenever Sport or Sport plus modes are selected.

 

Tough to trouble-shoot why it failed but as others have stated, a Battery Tender is a great way to avoid this in the future and does not take much time at all to install. Battery Tender's Plus is a solid product you can view here