I tested it today. My sequence looks like that: After start its at 12.2-12.1 for about 13min. Than it starts to increase to 12.7, 12.9, and finally 13.1 after about 20-25 min. Then it stays max at 13.2 for the remainder of the trip. After a short stop (I tested up to 4 hours) it starts up at 13.1V again right away. Seems that the intelligent BMS knows how long the car was off? Starts again at 12.2 when the car was parked for longer like overnight. Same happens even when car was plugged in Ctek overnight (Ctek shows fully charged), same sequence - starts at 12.2V....and then goes up.

 

dont know how i missed this thread when searching, i posted in another one, but i just ran into an issue. My MY22 C4S with RAS is 4 months old, 1800 miles.

I went away for a week so i put my car on the CTEK tender (Lithium battery, and i have it connected directly to the battery positive, and a negative post on the chassis, not through the cig lighter), locked the car/turned alarm on. Came home, tender showed it in the last stage - trickling. Unlocked car, unhooked charger, turned it on - started right up, but threw a warning "Battery low. Service required" error. But the car read that the battery was 13.4v. WTF? Drove around, it was fine but the error did not go away. Restarted the car a couple times, same thing - error is there but battery appears fine. I checked the voltage with a multimeter to make sure the reading on the instrument panel isn't wrong, and it was exactly the same.

I may have to take it in sooner than later to get it checked. This thread is not making me feel very good. this poster had good luck with a similar issue though, in that they found a fault with the battery diagnostic system and replaced it under warranty.

 

this. It should last at least 3 weeks, easily. Anything less than 2 weeks is broken* Assuming you aren’t patching in dashcams or other accessories. I wouldn’t expect any issue with the warranty. If the battery is discharging very quickly, it or BMS or the car is defective. By car, I mean unusual electrical draw when off, which can include any number of problems with the electrical system. The battery and car can be tested, so if your dealer tried to yank your chain on the warranty I’d just insist they test the car overnight for excessive draw and battery discharge.

* note very very short drives don’t count. The car needs some time at real highway speeds. And by some, I mean like 15 minutes a week.

 

For those with the Porsche Lithium battery; at what length of time away from you car do you decide to put it on a trickle charger? If you know you will be away for 1 week would you put it on? Or is it 2 or 3 weeks?

This thread has made me paranoid so just getting some advise

Also - do you have to shut your frunk completely when you on the trickle charger or can you leave it slightly opened??

Thanks

 

This is my 2nd 992 iteration with RAS. Back in early 2020 we did some non-scientific testing. I left my LiPo battery for 3-4 weeks at a time (this was just at the beginning of Covid, so more lockdown in place). 3-4 weeks without a charger on LiPo was fine. You likely could go longer, but at the time with the service centers at low staffing - I did not push it any further at the time.

Now if you are checking My Porsche App (meaning waking up the car when you do) - it may be less time. But I think in general you can go 4 weeks without an issue, and likely longer by a fair amount. My McLaren has a very small Lipo battery (actually has an indicator letting you know how many days you have until depleted) - it is a very small light weight LiPo. That one states you can go 45 days, in reality it is about 35 days. Knowing the battery is about 1/2 the size of the Porsche LiPo - my guess is you could go 2 months on the Porsche Lipo without a charger, and be ok.

I think in general to be safe - 4 weeks is conservative and should not have any issues.

 

Yes, I agree with you that some of these threads can make one paranoid. One reason I stopped believing half the BS I read on here and do my own independent research…as well as talking to my service/shop Forman at my Porsche dealership.

I’ve gone 2 weeks without putting my Li battery on a charger, and I am 100% confident i could go longer, but just haven’t gone there, yet. No issues. None. I’m pretty confident that if the battery can’t hold a charge for at least two weeks, there are other issues at play here, such as a defective cell on the battery, lose connector, drain in the electrical system (something left on in the car), or alternator not charging the battery, etc.

Personally, I think it’s silly to be hooking the car up to a charger after every run…but some people do it, for whatever their reason, real, or imaginary.

 

The problematic thing with the LG lithium battery is the stupid connector. From getting a low voltage warning to the connector dropping, it may be a very short amount of time. Once the connector drops, the battery is a goner most of the time.
The AGM gives more clues for longer period of time (difficult start, low voltage read and message etc).
Cold weather makes it way worse for both of them. All modern cars have constant battery drain.
I don't leave my car with AGM for more than 3 days without charging, but that battery is crapped out. My prior 997, 997.2, 991, 991.2 all were left for 3 weeks in more than one occasion, no issues whatsoever. Same for prior Cayennes.
The lithium battery on the current cayenne has failed twice. One month in the shop each time (as of now included). Warranty applied, not without a long discussion. Current SA is better, so there's a human element to warrant it.

I believe they use this connector to prevent overcharge and subsequent increased risk of fire. Also, the cayenne battery is in the cabin, you don't want an AGM gassing out with people in. Very bad press and memes. Not that the 911 battery is not just next to the cabin air filter...

 

It sure would suck if you take your 992 on a vacation and after spending a week or two there with the car parked in the hotel garage or airport that you have to be worry if it starts up. Never thought I will have that concern, for sure not with a Porsche.

 

One more data point... I was out of the country for 6 weeks. My car is a 2021 C2S with Lithium battery. I charged it with Ctek before we left but then disconnected the charger to see what would happen, Car is in my basement garage that is slightly heated. Windows up but car was not locked. When I came home I checked the voltage at the battery and it was 13.2. Got in the car and the dashboard indicated 13.2 as well. Car started right up.
Not sure what that means for the folks having "battery" issues but it appears, in my case at least, that the car can be left for at least 6 weeks, uncharged with no problems restarting.

 

Bingo. The take away is - no matter what people on here talk about, there will always be outliers where people have an issue. Doesn’t matter what. But most don’t. If there were a real issue, then I suspect there would be a recall?

I will also comment that a few on here talking about issues with Li battery, don’t even have the new Lithium battery. So, they bring nothing of relevance to the discussion. I’m out.

 

Good you have no issues. Happy for you. Unfortunately, my car died the first day of ownership (AGM battery). And btw, the fact I thought I have Lithium battery is simple - nowhere in my paper I got from Porsche does it say what battery I have and instead my car battery has a huge sticker on top saying Li-Ion! The first inclination is not to question Porsche that but search what can be done to remedy the dead car in a hurry. Even a casual google search at a Porsche parts supplier store listed it as Lithium. And apparently I am not the only one having battery concerns - Lithium or not. Sure hope I am an outlier but does that mean we can't ask on forums about it?

 

Another issue to report that may be related to battery

Vehicle - 2021 992 Carrera S/does not have Rear wheel steering
- AGM Battery
- Car picked up from dealer 12/21 after it sat in Davisville for a couple of months getting through emissions

Background - Car is on a CTEK charger every night attached directly to battery (negative on CTEK charger not attached to negative on battery but to bolt specified by Porsche)
- Running radar detector using mirror tap disconnected every time after use
- Running Blackview camera with Blackview battery disconnected every time after use
- Using Anti-gravity battery tracker

Incident - driving around town for about 20 minutes and then went to lax field to watch my daughter practice with car off. Also, turned radio off as I know how iffy these batteries are after reading various posts on Rennlist. I did raise and lower windows and sunroof a few times with car off (there was a bee outside buzzing around). After about 15 minutes I went to start the car to go home and it would not start and all of a sudden I started getting various warning/error message on dash:
-the Brake light was flashing in the dash, the parking brake light was flashing, key error warning messages, something about the door handle, transmission error messages etc.. Nothing at that time about the battery being low. It was about to pour rain and I had all the windows and sunroof open and could not close them. Decided to use a Micro Start device I had purchased from Anti-Gravity and it just barely started. I was able to get the car home and only then did the car tell me the Battery was low.
I checked my Anti-Gravity Battery Tracker and it showed that there was a steep drop in voltage for some reason (see attached chart - up to 9 am car was on CTEK, then took it off CTEK to wash before going out for a drive around 2:30). I checked the battery with a battery analyzer but was not sure what battery standard to use so I just used CCA @ 500 and it showed the battery was GOOD. I put the car back on the CTEK charger overnight and it cycled through to GREEN. Car started normally the next day with no error messages.
P.S. Drove car again today (noticed voltage reading in dash as low as 12.1 while driving) and heard a metal on metal scraping noise (seemed to come from front end, I think I may have heard a similar sound the day before). Turned car off and got out to look underneath but did not see anything. Tried to start car but it would not start and received similar error messages to day before. Will be getting it in to dealer. I'm a little concerned that they might blame battery tracker, radar detector and camera as cause for battery issues. Any thoughts?

 

They might, any aftermarket add-ons will always present a potential problem with the battery.

Another thing to note for those with battery issues is to check to make sure your car does not have a vehicle tracking system installed by your dealer (not Porsche). I know, I know, you're going to say, "No way, I didn't buy such a stupid thing like a tracker ..." but need I remind you that there are owners who have discovered trackers surreptitiously attached to the car only b/c they were fudging around with their car.

Just FYI, something to consider.

 

Thanks ipse dixit.

I will ask about the tracking device when bringing in for service.

 

Just to close the loop on the thread re: my battery issue. Took the car to the dealer today and was sweating out whether I would even make it there but luckily I did. I explained the 2 events over the weekend and they do their diagnostics and find the battery is bad. HOWEVER, since I drove less than the 6k per year as outlined in the manual the battery would not be covered under warranty (I've heard this approach/excuse used in other rennlist posts - Porsche is going to tell me how many miles per year I have to use my car - I don't think so). I told them the that they were going to have to do better than that and push back to Porsche and tell them:

a.). that when the car was delivered to the US it sat in Davisville trying to get through emissions for 3 months (that couldn't have helped the battery);
b.). that the car is trickle charged religiously and I had the proof to back that up (Battery Tracker from Anti-Gravity); and
c.). that the cigarette lighter functionality that was supposed to come with the car was broken and I had to go out and come up with an alternate solution to charge the battery.

I was fully prepared to escalate this to but the service manager came back and advised that they would settle at covering most of the cost (my cost $150 out of $873 total). Crazy right? All this while dealing with the 5 morning conference calls. Ugh.

Car runs great now by the way. Hope this helps someone. Interestingly enough the voltage signature in Battery Tracker looks different (more stable/less volatility) from the bad to new battery.