CaptainL

Hey guys. How long do our batteries typically last? I have a 2017 991 bought in 2019 so I know the battery is a least 3 years old. Start stop doesn't last very long and Volts are reading 14.7-14.8 when driving. I'm thinking its almost time for a new one?

JW911

It is probably the original battery. They are usually good for around 5 years give or take a year or two. So yours is around 6 yrs old. Start/stop is usually the first warning sign. If that starts to not work, it is time for a new battery. Get one from batteries plus, interstate, or another reputable distributor. Dealer will charge you triple.

CaptainL

Thanks! That's what I was thinking. Working on a quote from a local shop.

MingusDew

I’ve made it a habit to swap batteries in any used car I buy. I’ve had 2 year old batteries fail in cars purchased new (a Toyota no less..). Maybe I’m just less trusting, but a couple hundred is a small amount to spend for peace of mind. They take 15 min to swap out, maybe pay a shop if you don’t have any tools or a bad back, but it’s very easy to do. Now, onto my more controversial opinion, I wouldn’t waste $ on an ultra lightweight (Anti-gravity) type battery to save a couple of pounds. They’re going to fail in a few years and just triple replacement costs, so unless youre in a race class with a legit race car, spend your $ on more tires/brakes and becoming a better driver to shave lap times and not $1000 on a battery to save 40 lbs for bragging rights at cars and coffee or here on the forum. Interstate batteries are great 😊

asellus

100% agree.

I'd put money on 98%+ of people on rennlist being unable to produce a quantifiable difference between an AGM an a lithium-based battery. properly taken care of, lithium batteries and AGM batteries have the same lifespan. it's all just marketing wankery trying to sell you on saving some pounds on the wrong side of the car.

davidnyc

I just bought a used 2014 and had same issue. I followed a thread in this forum and bought a battery from Batteries Plus locally. Took me 15 min to swap the battery myself. Didn’t use a trickle charger. Swapped it like I swapped a battery in any other car. Just have to stand in the frunk because the battery is so heavy.

Tier1Terrier

My 2017 991.2 with original battery manufactured in 2016 is still working but I expect it to start showing signs to replace at any time since I'm already going on 6+ years with it.

asellus

+1, my 2017 was on the OEM battery until I sold it about a month ago at 67k miles. No signs of slowing down, either!

shammerman

2015 (in use 2014) 911.1 with 50,000+ miles. Original battery with no issues so far.

991_T

I replaced my original battery from my 2018 last year, It had low miles and must have sat without being on a trickle charger from time to time.
I purchased a AGM DEKA Intimidator I've had very good luck with these batteries with the RV & Enclosed trailer, I have one that's 7yrs old and still going.

barncobob

i replace every 5 years...cheap insurance for not getting stranded in BFE

IXLR8

For the original factory installed batteries.

2017 daily driver: 5.5 years and going strong.
2015 991: 7.5 years and going stong.
Previous cars: 14 years and 18 years for regular flooded lead acid batteries.

Porsche_nuts

Anyone buy the Pep boys Champion AGM battery? Specs are par with the others and comes with 4 year warranty versus most others that come with 3 years.

After 7 years, my OE is beginning to show some signs of slowing down.

UH2

I just replaced my original battery 2 weeks ago. It was 10 years old. I used a trickle charger during the winters when it was in storage in Ohio. The signs were starting to pile up that it was time, and I didn't realize how slow the cranking was until I put the new battery in. If I didn't drive it for a few weeks at a time (which wasn't out of the ordinary since moving to CA), I noticed that it was slow to turn over and weird things started happening like incorrect TPMS measurements...heated steering wheel notifications when I don't even have a heated steering wheel...etc. It was then that I knew it was time.

Yeah, you could probably stretch it out as long as I did, but why chance it? Like others have said, it's not a bad idea to swap the battery out on a used car and then maybe reassess in 5 years or so. Once the warning signs started popping up, all I could imagine is my being stranded in the middle of no where with no cell signal. Not worth it.

And yeah, everyone saying the swap is 15 minutes of easy work? TOTALLY TRUE. If you can turn a wrench, you can replace the battery. I spent more time driving back and forth to Batteries +.

IXLR8

By the way, a slow cranking starter does not necessarily mean it is the battery as I have experienced on a friend's 997. It could be the electrical connection/wiring harness or the starter. It was the starter after an unnecessary wiring harness was initially installed as per RL recommendations.