"Taycan lets you drive with shorted out battery modules"

[ct14garage]

Plenty of native English speakers with very very poor reading comprehension abilities.... Let's go part by part.

First of all, we've repaired way more than 5 batteries

This is the number of Taycan VINs registered in my company's ERP. 267 of them. Most of those 267 have had a battery repair. Last year (2024) alone we repaired 183 batteries. And sold 1567 individual modules. At my shop 2 lifts are exclusively dedicated to Porsche Taycan battery repairs ONLY! (I have another 3 lifts for any other car):

Taycan is an EXTREMELY popular and well selling model in Thailand. With over 6,000 units sold in the country most of them are unofficial imports, imported by private person and unofficial dealers here in Thailand which also import from Porsche dealers in the UK or Cyprus. These cars have no official Porsche warranty and are thus instead repaired at my shop.

Every week we repair on average 3 batteries, every single week. Not counting those that we help repair remotely.
Almost everyday I have Porsche HVE certified dealer technicians who work at the dealer asking me questions through Facebook Messenger. Because when they encounter a problem repairing a Taycan I reply faster, better than Porsche engineers and for free. Same way I have made many posts on the other forum showing how to repair many things for free.

I like giving back to the community, it's my duty.
Though at the same time I hate it when clueless morons make me lose my time by bullshitting around me with steaming piles of bs. Hence why Dee the moderator probably hates me. Cuz I've been impolite to many morons in his group. But that's fine, he's from the Netherlands, I'm sure deep down he understands the Max Verstappen no bullshit approach


ANYWAY, back to the topic in question. May I remind all of you that the title of the POST IS:

Taycan lets you drive with shorted out battery modules

Hence, discussing why the battery has water inside is a f'ing waste of time and irrelevant to the post(read the post title again, it's not about water inside the battery).

Most of them have water inside because they have been improperly repaired before by someone else. I have also seen batteries never opened before with a failed factory seal. But those cars could well belong to the recall campaign for the defective seal. So I'm not here to argue about this.

It is beyond the point, the POINT is that: ANY TAYCAN FROM THE FIRST UNIT SOLD TO THE LAST ONE WILL ALLOW YOU TO DRIVE WITH SHORTED OUT MODULES.

The car on the original post, came to the shop DRIVING, CHARGING BOTH DC AND DC. And the battery frame was LIVE while driving. BMS only showed a Yellow Electrical System Fault which sometimes turned RED but nevertheless you could still DRIVE.

As you can see this a FULLY SHORTED removed module from that battery. The BMS allowed you to DRIVE and CHARGE the car in this condition. This problem is still not fixed.

Somebody said that EVSE standard wouldn't allow you to charge if there was iso fault. In Thailand there is only 1 type of DC chargers that will refuse to charge when there is an iso problem. That is the DC chargers by PTT Gas stations. (And this is the charger itself not allowing the charge to go on due to iso, rather than the car itself refusing the charge)

Any other DC charger and AC charger (including Porsche mobile charger). That I have tried will charge as normal EVEN when the battery frame is LIVE.

Now to be honest, I have no idea what the theory behind EVSE charging is as somebody else said. But frankly I don't need to know the theory because I know the reality very well as I have done my own experiments and the car charges as normal with LIVE voltage on the battery frame.

This is DANGEROUS, and Chinese EVs as shit as they are and as shit as they drive. Electrically they are far far superior, and their BMS is extremely good and extremely rapid at detecting iso problems.

Hope this post clears it all up for you guys. Stop focusing on why there was water inside the battery, that is irrelevant to this issue.

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[Caraholic]

Just to add to the post above my car with the yellow electric symbol was fully drive able during the month I had to wait for service. When it got to service the master technician noted that the frame was live and he had to have it shipped off to a different dealer. This is a full time American Taycan that even went through and passed the Porsche CPO process. So I have zero reason to doubt him as I have had personal experience with it.

 

[Dee]

Hence why Dee the moderator probably hates me

I don't.
I just address complaints/issues and/or look after the general conversation standards.
Facebook is Facebook, don't take it too seriously.
I think this is a much better place for sharing your experience.
I have learned more about you and what you're doing too.

 

[ct14garage]

@Caraholic Of course it was fully drivable. And had you plugged into a 250kW DC charger, sure—it would’ve charged. Straight into the afterlife, perhaps.

Driving a car with isolation so bad that the battery frame is live is already reckless enough. But DC fastcharging in that state? Playing with fire—no pun intended.
The chances of a thermal event skyrocket.


This kind of failure is almost unheard of in the West. Nearly every Taycan there is still under Porsche’s 8-year battery warranty, barring a few exceptions. Any repair is handled by factory-trained technicians who follow Porsche’s procedures to the letter. No shortcuts. No guesswork. They do an amazing job. And this saves you guys big time.


If the battery is sealed as it should be, this kind of scenario is almost impossible. But once that airtight seal fails—whether due to a shady backyard repair or from factory defect under campaigns like ARB6/ARB7—the car won’t be too worried about it. It’ll drive and charge as if everything’s fine. Maybe you’ll get a yellow electrical system fault warning (which you can dismiss pressing the back arrow on the steering wheel) perhaps you even get the lucky red one but still drivable. Meanwhile, inside the pack, you’re sitting on a potential disaster.


P.S. Another common Taycan issue is individual cell failure. Each of the 33 battery modules contains 12 LG pouch cells. Sometimes a cell swells and drops to 0.0V, and due to the swelling it can make contact with the metal casing—an isolation fault. That one’s covered under campaign WRS1. But to be fair, the BMS usually catches this quickly (due to the voltage difference) and emergency shuts down the HV system immediately.

The BMS is good at handling voltage delta faults but not so much iso faults.

In my experience, WRS1 affected Taycans need not worry much about this. But ARB6/ARB7 affected cars better watch out.

If you got ARB6/ARB7 letter and your car suddenly shows a yellow electrical system fault, take it to service ASAP and if you really must drive it make sure to charge AC ONLY at the slowest possible speed (ideally 3.6kw/h). DO NOT DC charge a car in this condition.

 

[chun]

Just to add to the post above my car with the yellow electric symbol was fully drive able during the month I had to wait for service. When it got to service the master technician noted that the frame was live and he had to have it shipped off to a different dealer. This is a full time American Taycan that even went through and passed the Porsche CPO process. So I have zero reason to doubt him as I have had personal experience with it.

I wonder if this is another fail-safe failing.

All 3 times my car got yellow electrical circle (2x time from tesla chargers), the car would not allow me to put it in drive/reverse.

 

[ct14garage]

@chun That’s the Tesla charger either frying the OBC or crashing it with a fault which causes it to stop working (sometimes if you lock the car 20 minutes to wait for CAN BUS IDLE the OBC may restart if it had crashed and work again)

An OBC failure (understood as OBC no function) will cause the immediate emergency shutdown of HV system due to no component function (not being able to shift into gear).

In this case the fact that the OBC stops functioning shuts everything down before iso fault could even be an issue.

 

[chun]

@ct14garage have you serviced any 2025 facelifted taycan yet? Or any macan EV?

Are they any different from this point of view? I would hope they use a newer/stronger BMS that can detect problems faster.

 

[ct14garage]

@chun Macan EV uses CATL cells (Chinese ??). Completely different battery to Taycan.
I havent seen this issue in Macan EV.

PS: Yes, I personally prefer the choice of CATL over LG.
8 years ago 2017-2018 LG may have had the edge over CATL. But nowadays.... they're not even close to the Chinese in Lithium battery technology

 

[GTSS]

@ct14garage what is your opinion on why it is taking them so long to write the ARB6/7 software?

 

[BjörnfromHamburg]

It's the VAG genererally going strange ways in software and digitilization in the past 10 years.
In the 10s they obviously underestimated the topic.
Then the approach was "not too happy".
Probably need another 5 years to get ahead of software "issues".

 

[Dee]

@ct14garage how likely is it that you can drive with a shorted out battery module(s) and/or live battery case frame without any warning?
I understand there is at least a yellow warning (which should be red but that's another discussion).

 

[Jasper4S]

@ct14garage what is your opinion on why it is taking them so long to write the ARB6/7 software?

My guess; they are trying to find the cheapest option/solution. With the ‘postponed’ software they are buying time. The first whitleblower story was around 2022, broadly discussed on this forum. Making me think Porsche knew about this problem a year before we knew. There is no way software development could take this long. They designed the mission e in 9 years but they cant write a software update to do some basic diagnostics.

Logistically and of course $ wise, they want to avoid replacements at any cost

Disclaimer; these are my brain farts, no facts (yet?)

 

[Dee]

My guess; they are trying to find the cheapest option/solution. With the ‘postponed’ software they are buying time. The first whitleblower story was around 2022, broadly discussed on this forum. Making me think Porsche knew about this problem a year before we knew. There is no way software development could take this long. They designed the mission e in 9 years but they cant write a software update to do some basic diagnostics.

Logistically and of course $ wise, they want to avoid replacements at any cost

Disclaimer; these are my brain farts, no facts (yet?)

If this would be true and Porsche tries to cover up the problem, maybe we get a whole new battery with newer consistent modules, especially the early adopters (like me, lol).
But then again CT14 garage only sees bad batteries, the good ones drive around without any issues, let's not forget that.
But sure, it's kinda worrying...

 

[f1eng]

My guess; they are trying to find the cheapest option/solution. With the ‘postponed’ software they are buying time. The first whitleblower story was around 2022, broadly discussed on this forum. Making me think Porsche knew about this problem a year before we knew. There is no way software development could take this long. They designed the mission e in 9 years but they cant write a software update to do some basic diagnostics.

Logistically and of course $ wise, they want to avoid replacements at any cost

Disclaimer; these are my brain farts, no facts (yet?)

Probably just missing at least one key sensor to measure what is needed, so trying analysing sets of output from other sensors to extract the data they need.

Imagine, for example that you need an accurate measure of light but all you have is time and temperature. Could you do it? Probably not all that accurately.

Adding sensors to every battery module would require a big long recall on every car made.

If they knew what may go wrong at the design stage useful sensors for that eventuality may have been specified, but they clearly did not.

 

[ct14garage]

Probably just missing at least one key sensor to measure what is needed, so trying analysing sets of output from other sensors to extract the data they need.

Imagine, for example that you need an accurate measure of light but all you have is time and temperature. Could you do it? Probably not all that accurately.

Adding sensors to every battery module would require a big long recall on every car made.

If they knew what may go wrong at the design stage useful sensors for that eventuality may have been specified, but they clearly did not.

Pretty much, all you get from 1 module (12 cells) is the individual voltage from each cell and temperature measured at 2 different locations within the module. Any other data has to be inferred from these two variables alone.

Including identifying faulty modules.

Porsche HQ has a software that analyzes the VAL (Vehicle Analysis Log) created by technician with PIWIS 4 and pin points exactly the modules failed and those like to fail.

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