12v battery dead....again ('23 CT)

[pony1982_]

Quick update to report. Car still with the dealership - they called me over a week ago to say that the logs found a problem with the charging system and that needed to be replaced (I don’t have more info at this stage on what the problem was). They then told me a part had been ordered from Germany. Got a call earlier this week saying the part was expected on Saturday just gone so hopefully the car will be with me on Wednesday. I’ll try and find out more about what was replaced and post on here.

Sponsored

 

[Clod Reed]

Quick update to report. Car still with the dealership - they called me over a week ago to say that the logs found a problem with the charging system and that needed to be replaced (I don’t have more info at this stage on what the problem was). They then told me a part had been ordered from Germany. Got a call earlier this week saying the part was expected on Saturday just gone so hopefully the car will be with me on Wednesday. I’ll try and find out more about what was replaced and post on here.

what was the outcome ? Plz

 

[APJ]

Spoke to the guy at the dealership earlier. He seems to think it's something to do with a software update which landed in December - apparently it kept 'waking the car up', which causes the 12v to drain. I dont know why they didn't update the s/w when my car was with them over Xmas. What I dont understand, however, is why the battery wouldn't charge when plugged in or when the car was being driven. The HV battery on my car has consistently been above 70%.

I'll keep this thread updated with what Porsche find, but similar to others, I feel like I have a CTEK in my future.

I have a 2020 Taycan 4S from new and this dead 12v battery has been a real problem over the last couple of years. I was hardly driving the car and every couple of months I would try to get it out and had to call the "RAAC" as it wouldn't move. After it being dragged away on the back of one lorry, and actually put in the back of another (Porsche not wanting to see so many Taycan's on the back of RAAC flatbeds?)

I have since had the issue again a couple of weeks ago. This time the RAAC guy said, that charging the main batteries does NOT charge the 12v. It's just like any ICE car, it has to be charged by the car being driven.

So now I am taking it out at least every other day to keep the 12v charged.

It's going in the skip in Sept. And never a Porsche EV to be purchased again (they've cancelled most of their EV development plans, like most other OEM's, anyway).

BTW, I had one of the first Tesla S in the country in 2017 and did 136k miles over 8 years with very few problems. However, I won't be buying a Tesla again either. Will probably wait for the stunning new EV Jag.

 

[anonymouse]

So now I am taking it out at least every other day to keep the 12v charged.
It's going in the skip in Sept.

Seems like an overreaction.
Have you had the recent software update to the 12V battery management, which is supposed to fix the problem where the 12V misreports its status and therefore doesn’t charge?
Has the OPC looked to see if there is a fault or are there any accessories (trackers, dashcams etc) which could be misbehaving and draining power?

And you know that just powering it up will charge the 12v, you don’t need to actually put miles on it?

And if you are not driving for a couple of months, perhaps just pop it on a Ctek Lithium battery tender? Lots of cars (EV and ICE) need that if the car is sitting idle for months.

Hope you find a resolution. "Normal" Taycans do not have this issue, at least not as severely as you describe.

 

[eddieterry]

I had this problem for a long time but the software update to the 12V battery management system and 12 Volt switch has finally sorted it.
They also said I have a drain on the car when it is off and they have raised a ticket with Porsche to get a fix but say the latest 12 Volt software will keep it charged even with a drain. So far been perfect so do recommend anyone with this problem gets the latest 12 Volt switch software update.

 

[f1eng]

I had this problem for a long time but the software update to the 12V battery management system and 12 Volt switch has finally sorted it.
They also said I have a drain on the car when it is off and they have raised a ticket with Porsche to get a fix but say the latest 12 Volt software will keep it charged even with a drain. So far been perfect so do recommend anyone with this problem gets the latest 12 Volt switch software update.

Do you have to ask the dealer for this and take it in?

 

[eddieterry]

I did - phoned them and explained that this winter I was getting the problem of low 12 Volt messages as I had in both the previous winters. They said a 12 Volt Switch firmware / software update was available and should sort the problem out. They kept the car over a weekend monitoring the 12 Volt and then let me know that they had updated the 12 Volt Switch but had discovered a larger drain than normal on 12 Volt over the weekend when it was off. They sent the car back saying the charging should take care of any drain but have raised a ticket with Porsche and will have it back when they know the solution. 12 Volt now working perfectly.

 

[Isaac]

I did - phoned them and explained that this winter I was getting the problem of low 12 Volt messages as I had in both the previous winters. They said a 12 Volt Switch firmware / software update was available and should sort the problem out. They kept the car over a weekend monitoring the 12 Volt and then let me know that they had updated the 12 Volt Switch but had discovered a larger drain than normal on 12 Volt over the weekend when it was off. They sent the car back saying the charging should take care of any drain but have raised a ticket with Porsche and will have it back when they know the solution. 12 Volt now working perfectly.

Hi I had the same kind of issue and Porsche Germany were able to identify the cause of the battery drain - something to do with the heater - and the problem never came back even though I don't use the car much. This was with Porsche Tonbridge too.

 

[Tooney]

I did - phoned them and explained that this winter I was getting the problem of low 12 Volt messages as I had in both the previous winters. They said a 12 Volt Switch firmware / software update was available and should sort the problem out. They kept the car over a weekend monitoring the 12 Volt and then let me know that they had updated the 12 Volt Switch but had discovered a larger drain than normal on 12 Volt over the weekend when it was off. They sent the car back saying the charging should take care of any drain but have raised a ticket with Porsche and will have it back when they know the solution. 12 Volt now working perfectly.

Did you get the location of "the 12V battery sensor"? I'm interested in whether the hardware located at or right outside the battery itself, or within an ecu located somewhere else.

 

[eddieterry]

No - I didn’t ask.

 

[APJ]

Seems like an overreaction.
Have you had the recent software update to the 12V battery management, which is supposed to fix the problem where the 12V misreports its status and therefore doesn’t charge?
Has the OPC looked to see if there is a fault or are there any accessories (trackers, dashcams etc) which could be misbehaving and draining power?

And you know that just powering it up will charge the 12v, you don’t need to actually put miles on it?

And if you are not driving for a couple of months, perhaps just pop it on a Ctek Lithium battery tender? Lots of cars (EV and ICE) need that if the car is sitting idle for months.

Hope you find a resolution. "Normal" Taycans do not have this issue, at least not as severely as you describe.

Hey, thanks for this. I will check the latest SW updates, although, I think I have.

I did not know that just powering up the car would charge the battery. I have only been told that actually driving would charge it enough. I will do some. The mileage for a '20 model is not too bad right now at 28k, but as you say no point adding to it for the sake of it.

I don't think I would be so upset about these tech issues, if the model hadn't dropped its value like it had dropped its pants/jock strap!

 

[SergeyIndy]

Dropped the car off for the 2 latest campaigns, one is a recall since it is safety related (Rear View Camera interference), and the other is technically a workshop campaign which is the 12v sensor. The tech said for these 2 it will take 3 hours but no overnight. I will post the notes when done later today. I have not had a dead 12v after not driving the car may be for a month max, but it is always a concern that I am aware of, so hopefully, they fixed the logic for it to be sure that 12v is always topped off.

They can certainly learn from Hyundai as I recently bought one for my son, 2026 Sonata and it has a dedicated button labeled 12v battery, so when for some reason there is a drain, it shuts off short of complete circuit lock out enough to restart it with this button, so the driver just opens the door with the physical key, presses the button and all is back on - brilliant. I can tell you when my Cayenne drained its 12v when a 3rd party shop was helping me with the door hinge, the battery locked and the dealer said, $5k replacement of the 12v would be the only fix.

 

[jra]

This feels like a recent software update - my 12v flat today - it was fully charged on CTEC 9 days ago and HV battery charge on Thursday. Back to the dealer

 

[SergeyIndy]

This feels like a recent software update - my 12v flat today - it was fully charged on CTEC 9 days ago and HV battery charge on Thursday. Back to the dealer

Are you saying you got a flat 12v after the software update for it. I just got mine done with a thought that I do not need to worry any more, but may be not so fast...

Sponsored