tmarino

Installed the exact same battery with same disconnect scenario. No issues, no coding and runs perfectly. Job couldn’t have been easier.

IXLR8

I happen to still have the original factory fitted battery in my 991.1...80Ah.

They were available as a 70 (H6), 80 (H7) and 95 (H8) Ah according to Porsche part numbers.

barncobob

hope ur not on the road in BFE when it craps out..

DaveGee

Got it. I ASSUMED all OEM batteries were 80ah. Thanks for the correction.

DaveGee

981KMAN

So lets cut thru some of the confusion and misinformation.....

• Porsche designed the 981/991 cars to handle either an H6, H7 or H8 Battery Size.
  • The Battery Tray is made to accommodate any of these 3 size batteries.
• Many of the 991.1 & 991.2 Cars come with the H6 Battery Size from the factory.
• If you change the Battery Size from your original, you should have the Cars Charging System Software updated so its knows the correct size battery and can charge the new, different size battery appropriately. Not doing this may shorten the new battery life.

I have an H6 battery in my 2015 (6.5 years / 82,300 miles) and the battery is going strong, yet starting to show its age. Thus I am investigating replacing the battery with-in the next year.

Since I rather avoid paying the Dealer to update the charging system with different battery size information, I will replace my battery with the same size as the original. Save alittle on the cost and not incur and increase in battery weight (not that it matters much). Based on my driving style and usage, I will probably get another 7 years out of the new battery.

I have no issues with folks who wish to put an H7 or H8 sized battery in their cars that came with an H6. Only that they should realize that there is a difference that should be recognized.

visitador

This thread as become an example of telephone game. I believe the coding has to let the charging system to know there is a new battery and change the charging map. It has nothing to do with the size of the battery. This is kind of ancient history, but when I changed mine in 2019, the coding changed the voltage at idle to 12.5V, I think (and you don’t need a dealer to do that; an indi can do it with a diagnostic tool, Autel in my case). At that time, Costco was selling a H8 AGM battery (which was an Interstate battery). I think they discontinued selling it.

Also, one sure way to know you need to replace the battery is when the auto stop/start does not work anymore (i.e., engine won’t shut down at stop sign). I know, I know, none of us use that feature

spiderv6

I just did this today with the Duracell battery in post #1. Took about 30 mins and I’m about $500 better off based on what the dealer wanted. Did not use any power in between the battery swap and had zero loss of settings.

Thanks for the DIY

WEM 911 C4S

I want to thank Daberlin and all others that have provided helpful tips on battery replacement. My original 7-year old battery was starting to show signs of age and I decided to change it before it gave up the ghost. The recommendations on this forum were very helpful. The only battery in stock around here was the Diehard Platinum AGM, which looks very similar to the Interstate version. The install went smoothly and all seems to be normal again.

barncobob

I change every 5 years, cheap insurance

ericmeds

Disconnected batter and put on charger

After 5 min or so the car went absolutely nuts and started making clicking noises such as when you unlock but in rapid succession. Quickly unplugged charger. Window was down so I had to reset the auto sensor.

Turns out it didn’t lose any memory besides the time.

Any idea what happened? It was in the charging mode as displayed in OP’s photos

2010panny4S

Did this, unscrewed and detached what needed to be before I disconnected battery. No issues, it's relatively easy, no memory loss. Actual battery removal and connection not even 5 mins.

justabout

chargers may not have pure DC. There can be some waviness to the voltage profile. Older charges used to be like this. So I would never use a charger to power the car without a battery in the circuit. Good that you removed it immediately.

ericmeds

💯 Definitely do not understand the confusion around that part. The vehicle does not lose any memory besides the time (and I suppose ignition related readings).

Now post-change, I am still confused whether or not the BMS needs to be reset 🤷🏻‍♂️

UH2

I have a 2012.5 991.1 C2S with the original battery, 24k miles on the clock. I store it in the winter time (when I was in Ohio) on a CTEK maintainer and since moving to SoCal in February of this year, I don't drive it much (physical issue with my shoulder). I jumped in the car a week ago and started it, and all hell broke loose. The PCM told me was heated steering wheel was disabled. I don't have a heated steering wheel. Then the TPM told me my left front tire was -6 on the low side, even though the right side was at the same pressure and it was totally fine with that. I also noticed some oddities with having to repair my phone to my NM Automotive Android Auto unit. Then it hit me....the battery is probably getting low, and it's about time to retire it due to age.

I followed this thread, and ordered the Duracell from Batteries Plus. Approx ~$210 with a new user discount. I didn't bother connecting my car to the CTEK and the car was without a battery for 60-90 minutes. The install went easy, with the clock being the only thing that changed...but like someone above said, it updates itself within a few minutes.

Boy, I didn't realize how slow my car was turning over until I started it with the new battery for the first time!

Thanks OP and everyone else who has contributed. There was no way I was going to pay someone hundreds of dollars on top of the battery cost to do this simple swap.

I don't plan on having any coding/programming done.

UH2

CORRECTION: My Cab lost the ability to roll the windows back up after putting the top back on. I'm pretty sure I can find the procedure to fix this in the manual (hopefully). It should be a quick and easy fix.