Ok my battery is starting to get old and I want to replace it myself. I don't want to go the dealer for something I can do myself. Also I posted here about part of my wiring harness being chewed by mice over winter. Well when I went to pick up my car two weeks ago, they brought it around BUT did not pull it all the way out for me. I am retired from a famous law enforcement agency and my spidey sense was high, so I walked around the car and sure enough 4 inch scratch on rear bumper. Alright it happens own up to it. Don't want to go into it now but they did fix it very well. But left a very bad taste in my mouth. They knew and were hoping I didn't notice. In a word slimey! So I'm asking which battery and where to buy it. Others have said keep a battery tender hooked up to Acc. plug and no need to reprogram. True?

 

That's crazy about the bumper scratch. I bet you were tempted to pull your service revolver! Thank you for keeping us safe.

Porsche sure made an easy DIY task; of changing out your own battery, pretty complex on the 991. I've read several posts in our 991 Forum, and there are several opinions. Some say coding is required. Some say not. Some say an external power back-up is required. Some say not. Some say use an H7 battery, while others have used the larger H8. About the only consensus is to use a quality AGM type battery, like our OE battery.

Sorry. Wish I could be more helpful.

 

These will make it crystal clear, NOT:

https://rennlist.com/forums/991/9904...-question.html

https://rennlist.com/forums/991/9727...ry-advice.html

https://rennlist.com/forums/991/9746...g-battery.html (this may be the BEST one to read)

Happy 4th!

 

Thanks Lex I do always value your opinions as well as you wit as do others on here. Always like your comments! Trying to sort it out now.
Btw way, when I went to P/U the car NONE of the console buttons worked. No PSE, No Sport Sport+ Nothing. They fixed everything but Like I said sleazy.


LOL Revolver like it...old school man...LOL

 

do you want to name the sleazy dealer as I live in the area and want to avoid them

if you don't want to name publically, can you PM me

thanks

as for the battery, think Lex's post just about says it all, but I'd just buy a good battery and hook it up myself and not worry about the supposed "needed" programming

plus did insurance cover the rewiring from the mice?

 

Insurance did cover it. want to know why your insurance is sky high?? Check your inbox.

 

So how does this work?

I added the little triangular flairs to prevent buffeting in the cabin with the windows down. Unfortunately I had one of those cars that required the removal of the entire door card, which requires a battery disconnect to prevent accidental airbag deployment.

I disconnected the battery as instructed (I think it was on the ground side - but it was completely removed), performed the install, reconnected the battery, and the only thing I had to do was to reset the windows. Everything else worked, and I mean everything (key programming, PCM settings, clock, etc.).

So what's the difference between this and replacing the battery? I would expect the same results when changing the battery.

 

When I changed my battery it couldn't have been more simple. Take black plastic thing off, unplug old battery, unscrew battery retaining clip, put new battery in, screw retaining clip back in, plug battery in. Maybe 10 mins. No faults. I think I may have had to reset windows but that's easy.

 

I agree with jabs1542......I disconnect my battery cables ALL winter when in storage ( about 5 months ) without ANY battery tenderizer that almost everyone talks about on this forum . when I am ready to take the car out in spring I just put the cables back on and start the car.....no sweat. no reprograming none of that nonsense. everything works like I had it before I stored the car . just need to reset windows.

just follow Dewinator's directions...as simple as that.

 

The rationale is that the charging system adapts its behavior to the battery characteristics as they degrade over time. If the system charges your new battery while thinking it's an old one, the new battery's service life will presumably be shortened. When the dealer hooks up their PIWIS, they reset the charging system's parameters.

Of course, even if this is true, the cost of having a certified Porsche dealer install and code a certified Porsche battery is high enough that you'd probably come ahead if your aftermarket battery lasted only one year.

Against that you'd need to balance the fear that any electrical problems will be ineligible for warranty service if you didn't pay the dealer their baksheesh.