Is this the dreaded 12v battery issue?

TobbeG

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? The same fault happened to my car today ?

I had a software upgrade done 3 weeks ago, I had no problems at all before that and the upgrade was the first since delivery in August.

This Friday the car was completely dead after being connected to charger for 3 days. After calling PC assistance they had a guy come by on Saturday morning to open the frunk and charge the 12V Lithium battery.

I did a one hour drive and things were fine until this morning.
"Electrical System Fault..."

A new call to PC assistance and the car is going to the PC dealer/service centre first thing Monday morning.

Don't know yet what's going to happen but it's not that encouraging reading about all the troubles being reported.

Porsche Taycan Is this the dreaded 12v battery issue? 17269F79-FEAD-426B-B7F0-CAD7F401CD6B
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Tommy D

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Has anyone has had the problem that wasn’t using Porsche Connect? Seems like that is the root of the issue with the 12V problems.
 

SebastienBeun

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? The same fault happened to my car today ?

I had a software upgrade done 3 weeks ago, I had no problems at all before that and the upgrade was the first since delivery in August.

This Friday the car was completely dead after being connected to charger for 3 days. After calling PC assistance they had a guy come by on Saturday morning to open the frunk and charge the 12V Lithium battery.

I did a one hour drive and things were fine until this morning.
"Electrical System Fault..."

A new call to PC assistance and the car is going to the PC dealer/service centre first thing Monday morning.

Don't know yet what's going to happen but it's not that encouraging reading about all the troubles being reported.

17269F79-FEAD-426B-B7F0-CAD7F401CD6B.jpeg
Did you get any news from your PC? I've had the same problem as you did, twice: car dead, and then that same red message.
 

TobbeG

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Did you get any news from your PC? I've had the same problem as you did, twice: car dead, and then that same red message.
The Porsche Center did retrieve all the Error codes etc from the car, reset everything and sent the data to Porsche. They were then told to drive the car below 10% and then charge it fully.
When I got my car back it was fully charged, they said no software update was made and it has worked since then. They also told my not to use the APP's Timer charging - they say causing the 12 V issue and that the "Electrical fault" is a consequence thereafter.
 

SebastienBeun

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The Porsche Center did retrieve all the Error codes etc from the car, reset everything and sent the data to Porsche. They were then told to drive the car below 10% and then charge it fully.
When I got my car back it was fully charged, they said no software update was made and it has worked since then. They also told my not to use the APP's Timer charging - they say causing the 12 V issue and that the "Electrical fault" is a consequence thereafter.
Thanks for the info!
My PC told me that the factory asked not to keep the car connected to the charger once the charging process is completed. Instead, they want me to let the car "on its own" even if I don't use it for a few days. Apparently, the HV battery then tops up the 12V battery when required, instead of the charger (that supposedly sometimes fails to do so).
So far so good for me :)
 


REIL

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Thanks for the info!
My PC told me that the factory asked not to keep the car connected to the charger once the charging process is completed. Instead, they want me to let the car "on its own" even if I don't use it for a few days. Apparently, the HV battery then tops up the 12V battery when required, instead of the charger (that supposedly sometimes fails to do so).
So far so good for me :)
I just left my car in a non-heated garage average temp was 0C (in the garage) for 11 days while out of town. Outside temps 4C to -10C.
Battery was charged to 85% and showed 258 miles when I left.
Upon return it was exactly the same.
I did not look at the app or connect to the vehicle in anyway during those 11 days.
Treated it like any ICE car for this experiment.
 

wemct

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Thanks for the info!
My PC told me that the factory asked not to keep the car connected to the charger once the charging process is completed. Instead, they want me to let the car "on its own" even if I don't use it for a few days. Apparently, the HV battery then tops up the 12V battery when required, instead of the charger (that supposedly sometimes fails to do so).
So far so good for me :)
This sounds very strange. What your PC said doesn't make sense. I haven't read anywhere that the PMCC has any direct ability to top off the 12V battery or gather any information about the status of the 12V battery. It is my understanding that the conditioning of the 12V battery is always done via the big battery.

I have owned my Taycan for 9 months. Like many others, I leave my Taycan plugged into the PMCC whenever it is at home. The ability to plug it in and forget it is a big benefit for me to go EV. Due to the pandemic, I am in Georgia (location of the car) much less since the summer. There are a number of months that the car remains on the charger for 3 weeks in a row without being moved or unplugged without any issues with the 12v battery.

Although I don't need to use a Timer profile because I currently don't need the cabin precooled by my departure time, I am too lazy to change it so I'm still using the Timer profile to keep the the big battery at 85% without any 12V issues. I frequently access the car using the Connect app both when it is plugged into the charger and off the charger including last month when it was at the body shop for 4 weeks unplugged without problems. FYI, based on my VIN the software campaign was performed on my car, but the original 12V battery was not changed. It sounds like Porsche is still working on identifying the root cause and that the 12V problem does not affect all of the Taycans. Unplugging it from the PMCC when it is fully charged sounds like the latest guesstimate on a fix.
 

evanevery

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Thanks for the info!
My PC told me that the factory asked not to keep the car connected to the charger once the charging process is completed. Instead, they want me to let the car "on its own" even if I don't use it for a few days. Apparently, the HV battery then tops up the 12V battery when required, instead of the charger (that supposedly sometimes fails to do so).
So far so good for me :)
I'm calling BS on this... (Like so many other things dealerships seem to be clueless about)

If this truly is a car which I need to manually manage the charging process - then they can take it back. (Even Porsche software designers wouldn't be so stupid to make this mistake).

EV ownership is so much more convenient as ICE ownership as all you SHOULD need to do is plug your car back in when you get home. I've been doing this with 4 different EV's over the last 7 years or so. If I had to unplug my Taycan instead of leaving it plugged in then this truly would be a departure from what is acceptable.

My car has been sitting on the charger everytime/anytime it is parked in my garage (since August). Even if I just roll it out to wash it - it still gets plugged back in when I pull it back inside. Its always sitting there (at 85% charge) waiting for me. I don't use timers, custom profiles, or Porsche Connect. I just plug it in. Done.

People (and SC's) need to recognize that just because a car is "plugged in" doesn't mean its also "charging". The onboard charger is responsible for determining if/when the car should be charging (and when it should not). Is that lamp on your living room table always turned on? Its always plugged in, right? "Plugged In" does not mean "Charging"!

Its much more likely that something is waking up the PCM (Porsche Connect or Timer) and the PCM is not shutting down again and draining the 12V battery. Its not that the car is plugged in, its that something is "waking it up" while its plugged in...

Perhaps they are suggesting you "don't keep your car plugged in" so there is no REASON to wake it up? IOW: There is little point in setting a timer or using PC to adjust charging parameters if the car isn't plugged in... If this is truly what their angle is, then I would submit they would simply be better off asking folks not to use Timers or Porsche Connect until they resolve their problem.
 


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I agree with @evanevery here. Is it really the case that the only people who have discovered a dead 12V battery have been plugged in when it happened? I actually have always suspected that whatever wakes up to communicate is inadvertently waking up another system that does not naturally shut down in the same manner. This is why I have always wanted to know if the car was fully (and deliberately) locked by the owner prior to dying.
 

evanevery

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I agree with @evanevery here. Is it really the case that the only people who have discovered a dead 12V battery have been plugged in when it happened? I actually have always suspected that whatever wakes up to communicate is inadvertently waking up another system that does not naturally shut down in the same manner. This is why I have always wanted to know if the car was fully (and deliberately) locked by the owner prior to dying.
Not sure if this hypothesis would care whether the car was locked or not...
 

SebastienBeun

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This sounds very strange. What your PC said doesn't make sense. I haven't read anywhere that the PMCC has any direct ability to top off the 12V battery or gather any information about the status of the 12V battery. It is my understanding that the conditioning of the 12V battery is always done via the big battery.

I have owned my Taycan for 9 months. Like many others, I leave my Taycan plugged into the PMCC whenever it is at home. The ability to plug it in and forget it is a big benefit for me to go EV. Due to the pandemic, I am in Georgia (location of the car) much less since the summer. There are a number of months that the car remains on the charger for 3 weeks in a row without being moved or unplugged without any issues with the 12v battery.

Although I don't need to use a Timer profile because I currently don't need the cabin precooled by my departure time, I am too lazy to change it so I'm still using the Timer profile to keep the the big battery at 85% without any 12V issues. I frequently access the car using the Connect app both when it is plugged into the charger and off the charger including last month when it was at the body shop for 4 weeks unplugged without problems. FYI, based on my VIN the software campaign was performed on my car, but the original 12V battery was not changed. It sounds like Porsche is still working on identifying the root cause and that the 12V problem does not affect all of the Taycans. Unplugging it from the PMCC when it is fully charged sounds like the latest guesstimate on a fix.
I think that you are right indeed...
I've had my Taycan plugged into the PMCC when at home for months without any problem, then suddenly the 12V battery issue happened twice. I'll see what they come up with in the next few weeks, but in the meantime, I do as they recommended and I have to admit that it didn't happen anymore.
 

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I'm calling BS on this... (Like so many other things dealerships seem to be clueless about)

If this truly is a car which I need to manually manage the charging process - then they can take it back. (Even Porsche software designers wouldn't be so stupid to make this mistake).

EV ownership is so much more convenient as ICE ownership as all you SHOULD need to do is plug your car back in when you get home. I've been doing this with 4 different EV's over the last 7 years or so. If I had to unplug my Taycan instead of leaving it plugged in then this truly would be a departure from what is acceptable.

My car has been sitting on the charger everytime/anytime it is parked in my garage (since August). Even if I just roll it out to wash it - it still gets plugged back in when I pull it back inside. Its always sitting there (at 85% charge) waiting for me. I don't use timers, custom profiles, or Porsche Connect. I just plug it in. Done.

People (and SC's) need to recognize that just because a car is "plugged in" doesn't mean its also "charging". The onboard charger is responsible for determining if/when the car should be charging (and when it should not). Is that lamp on your living room table always turned on? Its always plugged in, right? "Plugged In" does not mean "Charging"!

Its much more likely that something is waking up the PCM (Porsche Connect or Timer) and the PCM is not shutting down again and draining the 12V battery. Its not that the car is plugged in, its that something is "waking it up" while its plugged in...

Perhaps they are suggesting you "don't keep your car plugged in" so there is no REASON to wake it up? IOW: There is little point in setting a timer or using PC to adjust charging parameters if the car isn't plugged in... If this is truly what their angle is, then I would submit they would simply be better off asking folks not to use Timers or Porsche Connect until they resolve their problem.
That definitely makes sense!
 

evanevery

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I think that you are right indeed...
I've had my Taycan plugged into the PMCC when at home for months without any problem, then suddenly the 12V battery issue happened twice. I'll see what they come up with in the next few weeks, but in the meantime, I do as they recommended and I have to admit that it didn't happen anymore.
I also doubt seriously as to whether the PMCC has anything to do with this... Folks have documented issues when using other chargers (EVSE's) as well...

Were you using a Custom Timer or Porsche Connect to alter your charging parameters AFTER you shut the car down for the evening?
 

SebastienBeun

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I also doubt seriously as to whether the PMCC has anything to do with this... Folks have documented issues when using other chargers (EVSE's) as well...

Were you using a Custom Timer or Porsche Connect to alter your charging parameters AFTER you shut the car down for the evening?
I was using a custom timer indeed because where I live, I pay electricity half the price during the night... But I never use Porsche Connect.

The thing is, I had been charging that way since I got the car in August last year without any problem. And then in November and early December I experienced that "dead car" issue twice in the course of a month or so...
 

evanevery

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I was using a custom timer indeed because where I live, I pay electricity half the price during the night... But I never use Porsche Connect.

The thing is, I had been charging that way since I got the car in August last year without any problem. And then in November and early December I experienced that "dead car" issue twice in the course of a month or so...
Yeah, lots of people seem not to have any problems. Until they do...

Timers and/or Porsche Connect seems to always be involved... Statistically, it could simply be that so many people use them. (However, I'm betting NOT...)

All it would take is one single person who WASN'T using Porsche Connect or a Timer to prove this theory wrong though...

Anyone?
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