My turn for a 12v failure.

[Mac_Gaz]

So, up until last Thursday, I’ve been rather lucky with my fault-free second Taycan (a MY 23 CT4S). The first one was a big bag of hassle but that’s a different story and Porsche eventually made good.

Anyway, back to last Thursday. I unlocked the car to get my charging cable out of the frunk, I plugged in, the car locked and the alarm started going off. I tried to unlock the car but the key was unresponsive. After 5 mins of the alarm sounding the car went totally dead. The doors were locked and the charging cable was locked in but the charger was inactive.

I called the OPC and got the stock answer to call Porsche Assist. They came out rather promptly and diagnosed a 12v failure and had me up and running again within a few minutes.

the car had only been standing for 4 days, there was no prior warning of the 12v battery being low and the Porsche assist gentleman could not give me any indication of why this happened. He did a diagnostic check on the car and said there was no indication of any faults except for the 12v going low and putting the battery to sleep.

Now, every time I use the car, I occasionally get the pcm warning and low 12v warning also sometimes appears. The voltage always shows 14.x when I’m driving and it doesn’t drop. That indicates charging from the main battery???

I’m going to be relying heavily on the car during next week, the question I have is, is it likely to fail again and do I need to book it in?

All advice and sharing of similar experiences greatly appreciated.

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[EVBHP]

Similar story here (started with alarm too). Eventually on the third P.Assist call-out in a 2 week period, the AA guy drove my car to the dealership (and got a taxi back later for his van).

Porsche said they had recently received "new advice" on Taycan 12v issues and my battery had been replaced. Didn't see any paperwork, but all fine snce.

 

[Flying ace]

is there monitoring we can do on the health of the 12v? Is there a particular voltage number to monitor for?

I take it the alarm issue is the key signal to look for right?

 

[Lee Chiacos]

The 12 V battery makes me nervous. Mine is now 3 1/2 years old and I wonder what it's doing down in there. When I go away, I am worried that it's going to die and I don't really feel like I understand how to properly take care of it. I also know it's really expensive to replace. How long will it last is the big question.

 

[cali25]

The 12 V battery makes me nervous. Mine is now 3 1/2 years old and I wonder what it's doing down in there. When I go away, I am worried that it's going to die and I don't really feel like I understand how to properly take care of it. I also know it's really expensive to replace. How long will it last is the big question.

Porsche needs to improve on its 12V battery tech as well as practicality, a 12V on most vehicle only costs $250, whereas, Porsche wants $4k. It's a bit ludicrous and a huge turn off.

 

[Gino]

Porsche needs to improve on its 12V battery tech as well as practicality, a 12V on most vehicle only costs $250, whereas, Porsche wants $4k. It's a bit ludicrous and a huge turn off.

4K? I thought it was ridiculous when I was hearing it cost $1K to replace.
This better not be the case.
If it is then it better have an 8 year 100K warranty as well and be included under the HV battery.
There is absolutely no way I will hand Porsche $4K for a 12V battery…

 

[cali25]

4K? I thought it was ridiculous when I was hearing it cost $1K to replace.
This better not be the case.
If it is then it better have an 8 year 100K warranty as well and be included under the HV battery.
There is absolutely no way I will hand Porsche $4K for a 12V battery…

It's true, $4k. I believe Porsche decided to opt for usage of lithium in its 12V batteries, which is suppose to last twice as long as the regular 12V that everyone else uses that only cost $250. However, longevity isn't Porsche's strong suit here, and failure is apparent on this forum. Every failure needs to be reported to NHTSA as well as European entities so that Porsche would consider this as a safety concern if passengers are left stranded.

And I agree, there needs to be a 10 year warranty if Porsche is charging $4k while other companies such as Tesla is charging $250 for a 12V swap

 

[Bossie]

I had similar problems recently: 12 volt battery went almost dead. No alarm activated but the PCM warned for a weak 12 volt battery and then the screen went black. The car was brought to the nearest PC by Porsche Assistance and stayed there for 5 weeks! The dealer could not solve the problem, hence, Zufffenhausen engineers had to interfere. But there are so many issues internationally that it took weeks to get them working on this problem via OTA (dixit my dealer).
When the car was finally returnedto me, the dealer could only confirm that several software issues had been solved.
Cross fingers but since then the 12v battery seems ok.

 

[Flying ace]

is the 12v battery issue covered under warranty? Also what is the battery type/model number/part number?

 

[cali25]

is the 12v battery issue covered under warranty? Also what is the battery type/model number/part number?

Base on what I am reading on forums, Porsche has a 4 year warranty on the 12V if the vehicle is under 50,000 miles. However, they also will try to void the warranty if you do not drive a specific amount of miles (base on Reddit posts), so beware. The poster on Reddit stared the labor and part numbers as follows:


Job # A Labor Total: $ 1,245.00


Cause:


Correction (s):


EL10 REPLACE BATTERY $1,245.00


Tech Number: 856 Labor Type: CP


Part Number Part Description Qty List


Parts Total: $ 1,952.52


9J1-915-105-NY LITHIUM


BATTERY


1 $ 1,952.52 $ 1,952.52


12176 REPLACED 12V BATTERY 500


REPLACED 12V BATTERY, CODED AND PROGRAMMED TO GATEWAY. CLEARED FAULTS. NO


ISSUES NOW.


Misc Total: No Charge


Job # A Total $ 3,197.52

 

[Flying ace]

Damn ! The problem is LiFePO battery is $1200! I just changed the battery in my 997 over the weekend. $180 including tax for a AGM, no programming. Good grief!

 

[Scandinavian]

1245 dollars for changing a 12 volt battery is just crazy. The Lithium battery is including the normal Porsche tax but the labour cost is ridiculous. In a BMW M5 you also need some ”coding” to link a new battery, but that is done at no charge.

 

[bastiaan]

I also had a flat battery last week. Very similar experience: parked to charge the car, plugged in the charger and walked away. Then got a call from the alarm center that my car was reporting being stolen. Of course it was still sitting where I left it, completely dead. Porsche assist got it running again and advised me to drive for 30 minutes to charge the battery.

I had been mostly doing short trips before this happened, and it seems those can drain the battery.

When I reported all this to my dealer (also to get the charge cable emergency cord reset which I pulled to get the cable out before the assist guy got here - stupid), they told me they can perform a battery reset routine which will reduce the risk of this happening again. No idea what this means and I don’t think it’s a recall. My car is going in in 4 weeks to have this done.

 

[davidh]

My 23MY Taycan has had the 12V battery go flat twice after 10 to 14 days of none use. The dealer couldn't find a fault which I think is software related. To stop the battery going flat when it's not being used, I use the Porsche connect app to pre warm (or cool ) the car. When this happens the traction battery charges the 12V battery. I follow this procedure once a week (when I'm not using the car) and terminate the warm up after about 20 mins to avoid excessive loss of charge for the traction battery.

 

[Tooney]

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