While on a trip to Austin yesterday I suddenly got a message that Steering assist was no longer available. Then the A/C stopped working. I turned around and returned home. Then I got a message that the auto start/stop was not available, though I already had it turned off. I suspected that the battery was going out, in spite of the fact that I always keep it on a CTEK tender. I took the car to OReily's to check it out. The clerk said the battery checked good but needed charging. Since I had just driven 100 miles I figured that the only thing that had been keeping it going was the battery tender. My wife previously had a '15 Macan that started giving me weird warnings and I took it to Porsche to find the problem. It was the battery going bad. They charged me $600.00 to replace it. Outrageous.
I checked OReilly's and Autozones prices. They were at $189.00 and $199.00, respectively. I then looked at Walmart's price. They had the Everstart H8 AGM battery for $149.00 plus tax, installed. I went home and removed the air compressor that sits in front of the battery and the strap over the top. Took about 15 minutes. Then went back to Walmart and they installed the new battery in about 15 minutes. I could have done the removal and installation myself but I'm old, tall and have sciatica. I just didn't want to get in the trunk and lift that 55lb battery. The aftermarket battery is considerably larger than the OEM but just fits the last tie down slot perfectly.
All said and done, everything works fine now with no warnings and I saved about $435.00. Some people say that the new battery needs to be programmed to the car while others say it is not necessary. I'm going to take the chance that it will be fine without doing that.
PS: Actually, the car is a 991.1 My oversight.

 

i did the Walmart battery too, no problems, fits perfect,,however i changed it myself,,,,i dont want a Walmart "tech" touching my car

 

I was leery of letting them touch my car also but they did it outside and I was able to watch the process. all went well.