2019 was a type-o.....I cant change the title. I have a 2017, not a 2019

hey folks, 2017 911s, pdk, 22k miles

last week my digital voltage gauge was reading 14.9 volts under normal driving

original battery

replaced the battery

Gauge reading 14.7 v

normal or do I need to look into this

thanks

 

Today's Porsches have regenerative braking, but do not charge when accelerating. More power available this way.
They charge the battery only when cruising, coasting, or braking.
And our AGM batteries require a high float voltage, and even higher charging voltage.
I don't see any thing wrong with the voltage you saw.

Just be sure to use a good battery maintainer like the CTEK, any time it will sit for 3 days or more, if you want long battery life. Otherwise, sulfation happens and it kills battery life.

 

Your number is consistent with what I see on 19C4GTS.

 

Yeah, as above, I don't see a 0.2V difference in apparent voltage reported at the Multi-Function Display as anything other than normal.

Curious though, as I also have a '17 C2, what made you get a new battery? Just decided 4 years was enough? Starting issues? Odd electrical gremlins creeping in? I'm in Florida where I typically felt lucky to get 4-5 years out of a car battery in the heat. I renewed my original '14 981S battery at about 5 years because I didn't want it to die on me at an awkward time, not because I was having problems. I just consider them lifed items, and my 991.2 is about at that point.

 

the reason I replaced the battery to begin with was that the voltage gauge was reading 14.9v, and it pegs at 15v, so, I was thinking my battery was going flat. I have 16 delivery date, so, I was going on 5 years, so better safe than sorry.

The old battery showed to be 73 percent charged, and I have an old A4 that needed a battery I will recycle the 911 battery!!!!

Thanks for the info!

 

Thanks, appreciate it. I may have learned something today; so you are saying that an increase in charging voltage might indicate a battery that is on the way out? Also, if you don't mind one more, how did you generate the number of "73% charged"? Was that the open circuit no load voltage across the terminals?

 

my battery charger gives me a percent charge when I hook a battery up

And yes, if a vehicle is overcharging it can be a low battery. The car overcompensates for the low battery charge.

 

I use a CTEK battery maintainer, anytime mine will sit in the garage 3 days or more, to avoid sulfation. Sulfation kills lead acid batteries. My 911 battery is 5 years old and still tests good.
AGM batteries do have a higher voltage than ordinary lead acid batteries. This is because AGM batteries use a different Alloy of lead.

 

I think if you edit your post and click on "Advanced" you can then edit the title.

 

Curious: What are y'all using to test the health of the battery?

I have a new OEM battery at the ready but my 7+ year old still gets it done - always use my CTEK for last 5+years ownership

 

You may not need that extra battery for awhile. I just replaced my original battery on my 2012 991 Carrera S. I was amazed at how long it lasted.

 

They do...in our 911s?

 

From a battery that is fully charged, a load test and a capacity test.

And don't waste your money on these 5 second conductance testers. You can do a real load test by using a Harbor Freight Carbon Load Tester. As for a capacity test, most of us cannot afford a Torkel 840/860 tester. I used those when I worked in a defense battery lab.

 

Also keep in mind... if you driving in colder weather you cars system will raise the voltage to compensate for the fact that Lead/Acid Batteries do not accept a charge as well when cold. So when its colder outside the system will charge at a higher voltage range. Also we know from alot of experiance that the Porsches and especially the GT4 will jump above 15v in the cold quite often. But no harm really. Not saying that is your issues just saying it one of a few that can cause higher voltage reading.... also putting it in SPORT modes do this because more electronics kick in....