12 Volt Battery issue now

[Martin Robinson]

That’s a good idea, Mark. Thank you. I will do that

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[SebastienBeun]

I'm all for providing valuable diagnostic info to Porsche. But, given all the time Porsche has known about this, and the fact that they still haven't solved such a major issue, I'm not sure I want to just give them my car have it sit at the dealership for days and days. Whats the point?

If (knock-on wood) I have this problem, I'm going to simply recover the car myself, get back on the road, and keep waiting for a proper fix.

That's exactly what I did both times this happened to me. But of course, I let them know it happened. It's better for me than having my car stuck at the dealership where they will... pretty much do nothing I guess except recover the car the same way I did.

Interesting fact maybe: the first time I got the problem, the car alarm was triggered just before the 12V battery died, which was a false alarm of course since the car was in my garage. When I got next to the car, the alarm was still yelling but I just couldn't do anything with the key fob. It kept going on for a couple of minutes, then went silent and the car was dead.
I can't tell if the alarm was triggered the second time I got the issue, but at least the car sent some message to the security company because they called me back telling me that there was something wrong with the car.

 

[SebastienBeun]

I had a 4S brick today. I have been conscious of the need to ensure that the car powers off properly so pretty sure it wasn’t that. Surprisingly, it only took 1 or 2
minutes on a back up 12v battery pack to get going again, which may suggest that the 12v wasn’t flat?

I had that 12V issue twice.
I'm pretty sure that you're right and the 12V battery isn't flat indeed. When you jump the car it's really like you were delivering an electric shock with a defibrillator.

My two cents: some bug disconnects the 12V battery which is actually not flat at all and jumping the car just closes the circuit again.

 

[Paan]

I had a 4S brick today. I have been conscious of the need to ensure that the car powers off properly so pretty sure it wasn’t that. Surprisingly, it only took 1 or 2
minutes on a back up 12v battery pack to get going again, which may suggest that the 12v wasn’t flat?

I have also been having a data connection issue over the last few weeks - no data connection for the eSIM showing up on PCM, although the SOS green light was still on. Also no Bluetooth connection for iPhone. The data issue kicked off when I started using the Porsche connect app to set the charging level. As a result of the data issue, the tracker is in permanent theft mode.

I do wonder whether the data connection/12v issues are connected. Of late I have heard a strange low volume electronic beeping sound coming from the dash which sounded like something trying to make a connection. I wonder whether the car has been attempting to make the data connection after the car was powered off and whether that drained the 12v - I hadn’t driven the car for 3 days.

When the car was restarted after he 12v issue, the eSIM connection and Bluetooth connection came back. However the data services aren’t functioning (tracker, Apple Music, internet radio).

All very strange.

Finally, the guy who came to restart the car wasn’t familiar with the nuances of opening and restarting the car. Thankfully I was, courtesy of being aware of similar issues encountered by others from this forum. I would suggest that everyone should familiarise themselves with what is involved.

I have exactly the same experience with the 12V battery only needing to be connected to the jumpstarter for 2 min and then everything comes back to live. This would not be the case if the battery was flat. I now keep a jumpstarter permanently in the car so I can reset everything myself without having to deal with the imbecile Porsche people who make sound like they never ever heard about the problem before. I’m waiting for the software update that will eliminate the issue.

 

[NC_Taycan]

First, when the car is "bricked" (which it isn't really since bricked implies it can't be recovered when indeed it can be), the 12V battery isn't flat - it just reached a voltage below which there is a relay that opens, disconnecting the battery to prevent it from being completely drained (which is bad for Li-Ion). Second, when you "jump" the car, you are supplying 12V to a computer which will re-energize this relay. It also wakes up the 800V system and DC-DC converter to re-charge the 12V. The reason you only need a small amount of time is that the 800V / DC-DC system is taking over.

 

[rquinton]

I have exactly the same experience with the 12V battery only needing to be connected to the jumpstarter for 2 min and then everything comes back to live. This would not be the case if the battery was flat. I now keep a jumpstarter permanently in the car so I can reset everything myself without having to deal with the imbecile Porsche people who make sound like they never ever heard about the problem before. I’m waiting for the software update that will eliminate the issue.

You have a simple method to Bering it back to life or do we always have to do the under the driver panel and the frunk jump? Is there a small jumper you suggest?

 

[Ferdinand]

My 4s is arriving in Feb, just to be on the safe side ordered this from Amazon
Upgraded Faraday Bag for Key Fob (2 Pack), TICONN Premium Faraday Cage Protector – Car RFID Signal Blocking, Anti-Theft Pouch, Anti-Hacking Case Blocker
May help the issue while at work.

Remarkable that it’s called Ticonn!

 

[mikeyyn]

Saw this the Youtube channel pcarwhisperer.

He said that you should make sure the PMCC should be set up at a minimum of 8 amps or it might kill the 12v battery. I asked how he knew this and he replied:

Hi Michael! There is a Technical Bulletin (TI) "2706 Discharged 12-Volt Battery After Charging the High-Voltage Battery" from Porsche that states when charging on a 120V at 6amps there could communication errors between the high voltage charger and Taycan which results in increased power consumption of the 12V battery which in turn can kill the 12v battery. The document recommends to keep the power output to no less than 8 amps when charging on a 120v in a pinch. There will be a software update sometime early this year to fix the error but it is not out yet. Hope this helps

Doesn't seem to fit with what others have been told by dealers, especially as some have had it with 3rd party chargers.

 

[daveo4EV]

at a minimum Porsche seems to be having a lot of problems with keeping some subsystem "alive/awake" draining the 12V battery for a variety of charging scenarios…and yes the problem does occur without the PMCC so Porsche has it's hands full dealing with issues…

 

[Andrew Rawson]

MY SPECULATION (and others as well I believe)...

...is that the PCM is waking up AFTER you turn off the car and then not shutting itself down when it should. Personally, I'm willing to bet a Charging Timer, or Porsche Connect (remotely), is waking up the car to change charging parameters and then the PCM does not shut down as it should. This would certainly drain the battery.

Personally, I have no need to use Custom Timers or Porsche Connect, so I'm not overly concerned about getting bitten by this bug. (here's hoping Porsche doesn't prove me wrong...) I simply have the charging level set to 85% in my default profile and always plug the car in when its in the garage. The more magic you can eliminate the better I think.

Its also important to consider that SOME of these battery failures might not be related to the major bug we are discussing. Its possible that there can be other unrelated failures due to leaving stuff turned on, chargers not properly charging (and THAT draining the battery), simple hardware failure, or other things around the periphery of this problem. 12V batteries can fail for a number of reasons. Its important that the chaff is eliminated from the wheat. (Not sayin' thats easy...)

For what its worth: My recommendation are:

- Don't use a Timer unless you need it.

- Don't change your charging parameters remotely via Porsche Connect (or the web site) unless you have to.

- Just plug your car in and leave it alone

- There is also another thread where folks have been told to keep their key fobs at least 10M away from the car so you might as well do that as well. Can't hurt, right?

MY SPECULATION (and others as well I believe)...

...is that the PCM is waking up AFTER you turn off the car and then not shutting itself down when it should. Personally, I'm willing to bet a Charging Timer, or Porsche Connect (remotely), is waking up the car to change charging parameters and then the PCM does not shut down as it should. This would certainly drain the battery.

Personally, I have no need to use Custom Timers or Porsche Connect, so I'm not overly concerned about getting bitten by this bug. (here's hoping Porsche doesn't prove me wrong...) I simply have the charging level set to 85% in my default profile and always plug the car in when its in the garage. The more magic you can eliminate the better I think.

Its also important to consider that SOME of these battery failures might not be related to the major bug we are discussing. Its possible that there can be other unrelated failures due to leaving stuff turned on, chargers not properly charging (and THAT draining the battery), simple hardware failure, or other things around the periphery of this problem. 12V batteries can fail for a number of reasons. Its important that the chaff is eliminated from the wheat. (Not sayin' thats easy...)

For what its worth: My recommendation are:

- Don't use a Timer unless you need it.

- Don't change your charging parameters remotely via Porsche Connect (or the web site) unless you have to.

- Just plug your car in and leave it alone

- There is also another thread where folks have been told to keep their key fobs at least 10M away from the car so you might as well do that as well. Can't hurt, right?

Hi Ed

you are absolutely correct, I have seen a memo from my dealership that says avoid using the PCM profile that sets charging times, there will be an update 1st 1/4 2021 that will rectify the issue.
I just wish this information was available when I took delivery.
I’m hopeful that Porsche will deliver this on time
hope this gives a little piece of mind to people

 

[chrisk]

there will be an update 1st 1/4 2021

April fool's day? Sounds like a joke.
What happened to that big January update?

 

[NC_Taycan]

Hi Ed

you are absolutely correct, I have seen a memo from my dealership that says avoid using the PCM profile that sets charging times, there will be an update 1st 1/4 2021 that will rectify the issue.
I just wish this information was available when I took delivery.
I’m hopeful that Porsche will deliver this on time
hope this gives a little piece of mind to people

Although I've had one 12V battery experience, I will disagree with this. Since April I have used both a profile with preferred charging times (min = 25%) and a timer with departure time (set to the end of preferred charging time window) and max = 85%. The one and only one time the 12V battery died just happened to be when I used the app to change the max from 85% to 100% after the car was plugged in but before it had started charging. Set your profile and timer(s) and leave the app alone while it's connected. Follow that simple advice and all seems well, based on my experience. And before anyone wants to re-re-re-re-restart the use or not to use timers / preferred charging times argument, I have a time of use rate plan and my setup cuts the cost to charge in half. If you don't, then do it your way and I'll do it mine.

 

[RRVV17]

Wow! That is a new one! 10 meters away just to avoid a drained battery?

That really sounds like a very desperate reason for the 12 volt issue.
To me that indicates more that they have not got a bloody clue what causes the 12 volt issues!

Very disappointing answer from Porsche

Agree. I've never (or not yet) had the 12v issue and admittedly I've left the key in the car overnight on occasion.

 

[RRVV17]

April fool's day? Sounds like a joke.
What happened to that big January update?

Think he was saying first "quarter" 2021. Hope dies last I guess.

 

[rquinton]

Although I've had one 12V battery experience, I will disagree with this. Since April I have used both a profile with preferred charging times (min = 25%) and a timer with departure time (set to the end of preferred charging time window) and max = 85%. The one and only one time the 12V battery died just happened to be when I used the app to change the max from 85% to 100% after the car was plugged in but before it had started charging. Set your profile and timer(s) and leave the app alone while it's connected. Follow that simple advice and all seems well, based on my experience. And before anyone wants to re-re-re-re-restart the use or not to use timers / preferred charging times argument, I have a time of use rate plan and my setup cuts the cost to charge in half. If you don't, then do it your way and I'll do it mine.

So for clarity, it is best to set up the charging profiles and timer on the car PCM and just monitor from the Connect App to avoid a dead battery?

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