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

[pony1982_]

So, this started just before Christmas. Got a call from Porsche connect in the early hours of the morning to check whether my car might have been stolen. I could hear the alarm, went outside, couldn't unlock the car to disable the alarm. Fortunately it switched itself off. Had a nice man from roadside come, who did the usual dance (get into the driver door, jump to get the frunk unlocked and then jump start the 12v battery which was dead). He told me to drive it for 20 minutes to charge the battery. I drove it for about 40 (worse things to be doing than driving my Taycan at 4am) minutes, got home and got a 12v battery warning as soon as I put the car in charge. Had roadside book it into the dealership (Porsche Hatfield) and they had it for two weeks before calling me to tell me there was nothing wrong with it (no obvious drains) and to take the car back.

Last week, I got the 12v warning again. I drove the car, charged the car, did everything I could do to get the 12v battery alive again, but to no avail. Spoke to the dealership this morning and the earliest they could fit me in was 2 April. Luckily or unluckily, the 12v went kaput again earlier this evening (alarm blaring, couldn't get into the car etc.). A nice man from the AA came out, told me something about it potentially being the DC to DC converter and that he wanted to escort me to the dealership (at 9pm) because he was worried it might come out while I was driving. Anyway, the car is now at the dealership (apparently there is a 2w window for them to look at breakdowns vs walk ins which are 6 weeks) and I'm feeling more than a little grumpy.

Forums seem to suggest this is a common problem with the Taycan, but not sure what resolution, if any, I should be pushing for. IS there something specific you'd suggest I ask the dealership to do? Dont feel like leaving it to them to do their thing feels like the smartest move, given they did diddley squat the last time it was with them.

Oh I'm also going to ask them to look at an annoying rattle from the back of the car.

Appreciate any ideas or suggestions. Thanks for reading!

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[kurand]

Mine suffered the 12V battery problem over the last few weeks too.

Called Porsche Assist (the AA) the first time to get into the locked car with the mechanical key to jump the bonnet release to allow external 12V to reactivate the battery. Subsequently, I have been leaving the car unlocked with the bonnet popped in the garage to allow easy access.

Car dead again yesterday, so called Porsche Assist again. The AA tech said that there must be an issue with the 12V battery or an unexpected 12V drain somewhere. They stated that the car needed to be taken into Porsche for diagnosis and correction. They got the car going again and had me drive it to Porsche with them following directly behind.

They also started the process of getting a replacement rental car because the Porsche Center didn’t have a spare loan car. This is where the whole outsourcing of Porsche Assist starts to break down and provides quite a poor service. The AA tech stated that the rental would be coming from Enterprise and that they have a 2 hour window to contact me regarding the replacement car. Therefore, I needed to make my own way from the Porsche Center. Doable, of course, but not ideal.

2 hours later back home and no contact from the rental company. Called Porsche Assist to enquire about when the rental company would call. They resent the request again to Enterprise (really???) who responded almost immediately. They cannot deliver the car to my home address because they don’t have sufficient staff and that I’d need to collect it from the lot. Too late for me to walk to their place to collect the car before they close, so i’m collecting it this morning.

Let’s see what happens about the 12 V battery and when.

 

[eddieterry]

Going by others who have had this problem Porsche are unlikely to find any problem with the 12 Volt. My personal view is that this is a problem of the main battery only charging the 12 Volt for a max of 30 minutes for up to 8 times which seems a problem in cold weather if the 12 Volt has been drained for some software related intermittent problem.
I find that the use of a CTEC lithium maintainer if leaving the car for over a week or if getting the low 12 Volt message is a simple easy solution.
I asked Porsche Tonbridge to check both the 12 Volt and software related to it but they found no problem which is why I use the CTEC.

 

[Isaac]

So, this started just before Christmas. Got a call from Porsche connect in the early hours of the morning to check whether my car might have been stolen. I could hear the alarm, went outside, couldn't unlock the car to disable the alarm. Fortunately it switched itself off. Had a nice man from roadside come, who did the usual dance (get into the driver door, jump to get the frunk unlocked and then jump start the 12v battery which was dead). He told me to drive it for 20 minutes to charge the battery. I drove it for about 40 (worse things to be doing than driving my Taycan at 4am) minutes, got home and got a 12v battery warning as soon as I put the car in charge. Had roadside book it into the dealership (Porsche Hatfield) and they had it for two weeks before calling me to tell me there was nothing wrong with it (no obvious drains) and to take the car back.

Last week, I got the 12v warning again. I drove the car, charged the car, did everything I could do to get the 12v battery alive again, but to no avail. Spoke to the dealership this morning and the earliest they could fit me in was 2 April. Luckily or unluckily, the 12v went kaput again earlier this evening (alarm blaring, couldn't get into the car etc.). A nice man from the AA came out, told me something about it potentially being the DC to DC converter and that he wanted to escort me to the dealership (at 9pm) because he was worried it might come out while I was driving. Anyway, the car is now at the dealership (apparently there is a 2w window for them to look at breakdowns vs walk ins which are 6 weeks) and I'm feeling more than a little grumpy.

Forums seem to suggest this is a common problem with the Taycan, but not sure what resolution, if any, I should be pushing for. IS there something specific you'd suggest I ask the dealership to do? Dont feel like leaving it to them to do their thing feels like the smartest move, given they did diddley squat the last time it was with them.

Oh I'm also going to ask them to look at an annoying rattle from the back of the car.

Appreciate any ideas or suggestions. Thanks for reading!

 

[Isaac]

2020 Taycan - 12 volt battery flat on Sunday night even though plugged in to charger.

First time this has happened but Porsche Assist person - who was excellent - said he had seen a lot of these recently and speculated that it was an OTA software update gone wrong.

Question in my mind is whether this is connected to a fix for the ridiculous Dec 24 letter from Porsche warning me not to put the car in the garage because it might catch fire - which the dealer knew nothing about.

This is clearly a systemic problem. The short term solution - and its a disgrace that this is necessary - is (as others have said) to fit a CTEK lithium battery charger to keep the 12 volt battery charged up whatever the car is trying to do.

Another interesting thing is that the dealership said it would take 2 weeks to look at it as they are swamped - in part caused by other dealerships were not taking in cars that had broken down....An utter shambles all round.

 

[kurand]

I’ll wait to see what PRG Reading (colocated with Porsche UK HQ) find with my 12V battery. If they claim they can’t find a problem, then i guess i’ll be forced to buy a new battery charger. I actually already have a CTEK charger for the AGM battery in my track car, but that won’t work on the Taycan, so i might be tempted to splash out on a lithium battery for the track car when buying the new charger.

 

[pony1982_]

Going by others who have had this problem Porsche are unlikely to find any problem with the 12 Volt. My personal view is that this is a problem of the main battery only charging the 12 Volt for a max of 30 minutes for up to 8 times which seems a problem in cold weather if the 12 Volt has been drained for some software related intermittent problem.
I find that the use of a CTEC lithium maintainer if leaving the car for over a week or if getting the low 12 Volt message is a simple easy solution.
I asked Porsche Tonbridge to check both the 12 Volt and software related to it but they found no problem which is why I use the CTEC.

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.

 

[Leverage]

Same problem with my '23 CT. Porsche told me there wasn't anything wrong with my car... a few weeks later I got again the message that the v12 battery was low... I din't wait. I bought a v12 charger and charged the battery up. No more problem since. Fingers crossed.

 

[asiviero]

Same problem with my '23 CT. Porsche told me there wasn't anything wrong with my car... a few weeks later I got again the message that the v12 battery was low... I din't wait. I bought a v12 charger and charged the battery up. No more problem since. Fingers crossed.

you should notice when driving your battery going as low as 13.2 and immediately get bumped up to 13.5/14. if this doesn't happen better ask the dealer to fix it. could be just a software error that prevent the battery to be re-charged, but it will avoid you stopping in the middle of nowhere.

 

[eddieterry]

you should notice when driving your battery going as low as 13.2 and immediately get bumped up to 13.5/14. if this doesn't happen better ask the dealer to fix it. could be just a software error that prevent the battery to be re-charged, but it will avoid you stopping in the middle of nowhere.

Most people report that once the 12 Volt battery has been re-initialised then the charge shows 14.1 or 14.2 when car turned on so this is not a problem when driving.

It seems to happen when the car is left for a short or long period of time and then keeps showing the 12 Volt low until it has been charged by CTEC. Most likely a software proble.

 

[Horizontally Opposed]

I have ‘24 CT. Have had zero problems with 12V, but did have a rattle in rear from day one. There was a tsb for a rear latch problem. I think they actually modified the latch to a new design. Once replaced, no more rattles.

 

[ItsNot AboutTheMoney]

I would strongly recommend to install a bluetooth 12V Monitor
to check remotely with your phone App the state of charge of your 12 V battery.

Amazon.com https://www.amazon.com/gp/product/B01MT4583U/

Android https://play.google.com/store/apps/details?id=com.dc.battery.monitor2
Apple https://apps.apple.com/us/app/battery-monitor-bm2/id1115492033

This will allow you to check when your car goes to sleep,
and also how often the 12 V battery get recharged when you are not driving.

Typically, after two days, when the voltage reaches about 12.5V,
the in-board DC/DC charger run at about 14.5V for two hours.

While driving the in-board DC/DC charger runs at about 13.5V,
so the battery doesn't get discharged running accessories,
in a similar fashion as the alternator of an ICE car.

This would allow you to determine if the DC/DC inverter get activated
when the car is sleeping for a long time and also to determine if your
12 V battery starts to be too old and could not keep the charge, and
need to be constantly recharged:

 

[Jagu]

Can someone please post a link to the appropriate CTEK battery tender to buy for this car? I had the same issue 3 weeks ago, but the dealer couldn't find any problems with the battery.

 

[eddieterry]

I think for the USA the model is:
CTEK 56-926 LITHIUM US | Fully Automatic Lithium Ion Phosphate LiFePO4 Battery Charger | 5.0Ah - 60Ah | Maintenance Charging up to 120Ah

 

[eddieterry]

Link:
https://www.amazon.com/CTEK-56-926-LITHIUM-Automatic-Phosphate/dp/B00EUF6UM8/?th=1

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