I think when you have start/stop enabled but the car never decides it is "ready" to do an automatic engine shutdown and restart it's a sign your battery is ready to be replaced. By never, I mean never, not sometimes. I rarely enabled auto start/stop in 49,500+ miles of driving, but before I replaced my battery, I did several times just to see what happened, and the disabled symbol would always show in my MFD dash display. I know it worked several thousand miles before. The main symptom that clued me in on my battery was the sound of the cranking starter motor. Just didn't sound as snappy as it did when the battery was newer. So at 5.5 years of age, I replaced it. Now auto start/stop works (even though I don't use it) and battery cranks the engine like when the car and OEM battery was new.

 

My 2015 Cayman was on its original battery and lately had begun to show some odd behavior in cold weather despite being connected to a Porsche Charg-O-Mat most of its idle time during the last year. So, I decided to replace the battery. I bought a Duracell Platinum 94R AGM, 80h, from Batteries Plus and installed it myself. Interestingly, while the new one is a 94R (I.e., H7) like the old battery, the length of the Duracell is more like an H8. I kept the car connected to the tender through the footwell socket during the switch, though the battery was disconnected for just 10 minutes or so. I don't think I lost any settings, but I reset the windows anyway. I immediately noticed much better Stop-Start capability and all of the electronics seem to be working as they should.

After a day, I bought the Autel AP200 code reader for ~$70. I was able to use the reader to register the new battery.

 

Did the Autel AP200 give you the option to change from lead-acid to AGM? Plan to upgrade the next time I need a new battery.

 

I also bought a Duracell AGM battery and an OBD tool total cost of swapping the battery myselft about 290 USD vs the 700 USD the stealer is asking. You gotta be gullible or filthy rich to go with the dealer option

 

Yes. The registration screen has entries for capacity, type (AGM. wet, etc.), serial number and Porsche part serial number. For the latter, I used a number I found online for a Porsche "OEM" 80ah battery.

 

Well, not necessarily. The battery replacement process is pretty straightforward, but to DIY you need motivation and a strong back. My local Batteries Plus said they would not do an install on a Porsche.

 

Well you don't need a strong back you need strong arms and make sure you don't tax your back, you gotta know how to lift heavy objects without taxing your back, also if you go inside the frunk firs then introduce the battery on the battery tray its easy, for me 500 USD of savings is a strongh motivation, not just about the money but for the feeling of not have being ripped off.

 

Replaced battery in my '16 CS with this:
O'Reilly's Auto:
Super Start Platinum Battery Group Size 48 H6 48PLT | O'Reilly Auto Parts
as suggested above. Battery was disconnected for all of two minutes, and on the ensuing drive the auto stop/start worked at the first light (not that I wanted it to, but you know how we are).
Did not notice any other difference in car, cranking is not different.

Edit: in thinking about this more, it's interesting that the auto stop/start has not worked for two years, but the car has always cranked fine and the dealer rated the battery as good when it was serviced in the Fall.

 

I would also be interested in this if anyone knows, please. I know it's the 981 forum but since he asked the exact question i had in mind i thought i wouldn't make a separate thread.

 

go with what you currently have (flooded). AGM was added to 991/981 due to start/stop feature because of AGM’s slower discharge.

 

I was able to find an H6 @ 760 CCA at Costco. They don’t advertise it on their website D’s car finder unless you go in and walk. I’ve noticed that at many auto stores: they all recommend H8 but H6 will fit and work just like the old Banner battery. No need to go up in size

 

IF you are ever looking to never be stranded by a dead battery again you can look into our latest Lithium-Ion direct replacement Battery in the H6 or H7 or even H8 sizes.

Features are built-in Wireless Jump Starting.... so you will NEVER be stranded by a dead battery again. Weighs 35 lbs less than a lead acid battery. 8-10 year lifespan.

You can see them here. https://antigravitybatteries.com/pro...tive/ag-h6-rs/

 

OK understand the TYPE now, was wondering about the battery age, where is the manufactured date stamp, etc.

 

On the stock battery, its stamped on the battery terminal post itself. I think its a week number and the year.

 

Found it, on the "Top" of the negative Post. 4 digit month and year