Taycan Problems are overwhelming an otherwise great car

[Scandinavian]

Latest update on my car is there are TWO battery modules that need to be changed. They are still estimating early October when they can fly in the tech from Atlanta to do the switch out. I'm not sure why they aren't changing the HV battery charging control unit - I guess they haven't found any 'error codes', but I'm concerned the HV charger might be part of the problem. Any thoughts??

No news so far on my progress. The car seems to be in the workshop at the moment with reports of 0% charge and 0 km range? Guess they have moved the car with a jump start and rolled it into the workshop.

My report was the same, two modules, I think 10 and 30 needed replacements.

And my belief ( after discussing with the previous service manager) is that the HV Battery Control Unit is closely linked to the Charger, if not the charger itself?

I plan to call them tomorrow for an update and will let you know status then!

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[Vim Schrotnock]

Let's definitely keep everyone posted here. It sounds like you have almost exactly the same situation. I may have missed this, but how many miles on your car? Mine has just over 30K. I went in to grab some things out of the car and it was completely dead, just sitting inside in the service lane with 0% power - we couldn't even open the doors - had to do it manually. I just wrote the service manager to see if they have identified what caused the modules to go bad, and if they intend to replace two modules, but not the HV charging system. At this point, I haven't heard they are planning on doing or have done anything to test the system or determine what caused the bad modules, but of course if I have a system that is causing modules to go bad after a period of time, I want it replaced.

 

[Vim Schrotnock]

Latest update. I spoke in person with the chief technician, of which there are only 11 in the US, who had flown in from out of state to replace the two defective modules in my car. We had a great and very informative discussion, and thanks to my Dealership to allow me to be on the shop floor and ask any questions I wanted.

I first wanted to know if he could pinpoint what happened to my modules, and if it had anything to do with the HV charging system. There was absolutely nothing wrong with the HV charging system, and the software was up to date. The first module was out of spec by just a few tenths of a volt, and they had to run the car down to about 10% to see this. They also replaced the second module out of an abundance of caution because it could have been affected by the first module (not sure on the specifics here). I asked how many of these defective modules he'd seen, and ballpark very few - maybe a couple dozen. He guessed the module had a bad cell from the beginning, and I just never saw it because I'd been charging to 85% pretty much every day. He said he hasn't seen any significant problems with the onboard HV charging system.

I asked about best charging practices, and he said the 85% each day was fine, but every month or so I should let the charge run down to 10-20% and let it sit overnight. Evidently this helps the system 'balance', and will identify if any of the cells are having problems. He was very confident that the battery and entire charging system will be as good as new, or maybe even a bit better with the new cells.

The other interesting thing was that the range calculation is based on your driving style/habits, and that's one of the reasons I typically see 230+ mile range on 85% charge. I get my kicks on the racetrack, and really baby the car in normal driving. I try to be smooth with minimal use of the brakes - and yes I occasionally hit the go pedal to the floor, but typically for a good reason, such as I want to detach myself from surrounding traffic.

The following information was from an anonymous source, whom I promised not to disclose. The battery capacity is indeed conservative, about 5% on the high end (5% more than the 93.4kWh), and about 10% on the low end. What this means is that some unnamed Porsche technicians have driven their cars down to -5% a number of times and once down to -9% but wouldn't recommend this for sure. Nice to know there's a reserve that you can use if you really need it, and this certainly should reduce range anxiety.

In terms of future battery technology, the new Macan will have a different battery layout with larger modules, but the battery chemistry will be the same. Solid state battery technology will give us more than 2x the capacity, or less than half the weight of the current 1400 lb battery. This likely won't happen until I'm ready for my next Taycan - in 5-7 years.

I'll be picking up the car early next week, along with my Vgate OBDII, and I'll report back when I have some good data.

 

[Tooney]

The following information was from an anonymous source, whom I promised not to disclose. The battery capacity is indeed conservative, about 5% on the high end (5% more than the 93.4kWh), and about 10% on the low end. What this means is that some unnamed Porsche technicians have driven their cars down to -5% a number of times and once down to -9% but wouldn't recommend this for sure. Nice to know there's a reserve that you can use if you really need it, and this certainly should reduce range anxiety.

I'll be picking up the car early next week, along with my Vgate OBDII, and I'll report back when I have some good data.

Glad your car is getting back in action soon.
The info about being able to drive Taycans below 0% SOC seems to conflict with several YouTube videos done a couple years ago depicting range tests in which the cars were driven to 0%. The cars essentially stopped. In some cases they were able to be restarted and moved slightly.

 

[Vim Schrotnock]

Glad your car is getting back in action soon.
The info about being able to drive Taycans below 0% SOC seems to conflict with several YouTube videos done a couple years ago depicting range tests in which the cars were driven to 0%. The cars essentially stopped. In some cases they were able to be restarted and moved slightly.

Interesting. If you think about it, Porsche would be in big trouble if they indicated even .5% SOC or one mile of range left and the driver was stuck with no battery. This is one of the reasons every car has a gas gage that indicates empty when there is actually some gas left in the tank. I think we have to have the same situation here.

 

[Tooney]

@Vim Schrotnock Videos of Taycans run out of battery:

 

[Vim Schrotnock]

Interesting. Not sure how the techs ran the cars down to negative percentages - certainly they were monitoring through the OBD since the car won't show negative numbers. However, looks like you better pay attention to the actual range when it gets close to zero. Interesting that the car went into 'limp' mode, rather than leaving the driver stranded...

 

[Scandinavian]

I'll be picking up the car early next week, along with my Vgate OBDII, and I'll report back when I have some good data.

Great to hear that you can pick your car up next week.
My car has been repaired with 2 new modules and a new HV Battery Control Unit for about a week now. The repair in total took them about 2 weeks at the battery repair centre in Stockholm. Seems they hot parts etc in time.

How ever I still will not see my car for some time it seems. Porsche Assistance have been abysmal and so bad I just can not believe it. They have known for for a month now that they need to arrange transport of my car back down to South of France. Fair distance 2500 km, but they have done absolutely NOTHING to prepare for that. The now have told me they need to get quotes in and approved for a transport! They could have done that 4 weeks ago! Then the transport may take a month or so. I think even by horse carriage it could be done faster???
Extremelt disappointed with Porsche promises related to their Porsche Assistance as Part of the Extended Warranty.

So no car in sight for some time

 

[Vim Schrotnock]

Great to hear that you can pick your car up next week.
My car has been repaired with 2 new modules and a new HV Battery Control Unit for about a week now. The repair in total took them about 2 weeks at the battery repair centre in Stockholm. Seems they hot parts etc in time.

How ever I still will not see my car for some time it seems. Porsche Assistance have been abysmal and so bad I just can not believe it. They have known for for a month now that they need to arrange transport of my car back down to South of France. Fair distance 2500 km, but they have done absolutely NOTHING to prepare for that. The now have told me they need to get quotes in and approved for a transport! They could have done that 4 weeks ago! Then the transport may take a month or so. I think even by horse carriage it could be done faster???
Extremelt disappointed with Porsche promises related to their Porsche Assistance as Part of the Extended Warranty.

So no car in sight for some time

Bummer! That is truly terrible service. Let's keep everyone posted and compare notes on the repairs. Hopefully, as my tech said - 'should be as good or better than new..."

 

[Vim Schrotnock]

Have my car back! Everything looks good, and I plugged in Vgate iCar Pro using the Car Scanner app and it is terrific! For $30 bucks it's definitely a great buy, and gives you hundreds of data points on pretty much everything your car is doing, or has done (didn't think I had done 32 launches... ). The estimated mileage is back to normal, giving about 270mi at 100%, and battery SOH is 91%. It's very interesting to look at the individual cell voltages. They vary from 3.601 to 3.629. Can you guess which cells are in the replaced modules?

 

[Sace]

Can you guess which cells are in the replaced modules?

Congrats on getting you car back. Did they replace other things than just the cells? It feels like these cars have an issue with balancing the individual cells - Wonder what they do to prevent these issues reoccurring. It must be super expensive for them to do these kinds of repairs.

 

[Vim Schrotnock]

They had to replace a drain tube that was damaged during battery removal, but other than that, just the two modules. I did ask specifically about whether the problem would recur, and the tech felt the single cell was probably defective from the beginning, and felt very confident the other cells, AND the HV charging system/software was good for long-term. Yes, it is quite expensive for this kind of repair - flying a tech in from Atlanta for three days... They replaced the second module out of an abundance of caution, so I feel pretty good about this as a long-term fix. ?

 

[Dr Bob]

I first wanted to know if he could pinpoint what happened to my modules, and if it had anything to do with the HV charging system. There was absolutely nothing wrong with the HV charging system, and the software was up to date. The first module was out of spec by just a few tenths of a volt, and they had to run the car down to about 10% to see this. They also replaced the second module out of an abundance of caution because it could have been affected by the first module (not sure on the specifics here). I asked how many of these defective modules he'd seen, and ballpark very few - maybe a couple dozen

Vim,

Only just seen this thread from the link you posted in the other thread I was commenting on re balancing.

https://www.taycanforum.com/forum/threads/charging-to-80-or-100.17448/page-3

I think what you have been told is very plausible and it was a bad module (not sure how many cells in a module?). Very possible the capacity of the bad module was lower than the rest – modules have to be very closely matched otherwise when top balancing, the modules will be nowhere near balanced at the bottom. Charging to 90%-100% will stress the bad modules when you run it at very low SoC range. As soon as one set of cells (ie a module) gets well out of balance at the bottom end then there will be knock on effects. 0.2V difference at 10% SoC could be significantly bigger at 1% SoC. It is entirely possible that when the bulk of the bank gets down to 10% SoC, a very bad set of cells with a large reduced capacity could end up at 0V and bye,bye cells.

I've only been a Taycan owner for a month and been here the same amount of time but I seem to be reading far more battery issues like this on Taycans rather than the Tesla M3 forum I used to monitor. Maybe the quality control on the cells they use is not as good (ie using closely matching cells) but then the Taycan charges very differently and hence stresses the cells more (voltage, speed of charge, increased power of charge, etc) and also discharges at faster rates to develop the much higher horsepower so more stress on the cells.

I'm an optimist. I am sure it is only a few bad cells as there are so many who have not experienced the issues.


Glad they found the problem and you got it sorted.

 

[Dr Bob]

The first module was out of spec by just a few tenths of a volt, and they had to run the car down to about 10% to see this.

Vim, just to add to my post above. Putting my brain in gear.
A few tenths of a volt (0.2V) is 200mV. On my LiFePO4 boat batteries, when manually balancing them, I am looking for a max delta across the 4 modules of 20mV if possible and certainly no more than 50mV - all at around 3.5V per cell which is around 95% SoC. 200mV would be very un-balanced. (Top balancing)
If you therefore have a delta of 200mV at 10% SoC, then that could be up to 1000mV at 0% SoC. Definitely a bad module. Those deltas would not show up in the plateau and top voltage knee.

 

[Vim Schrotnock]

"Cell pouch 5 in module 1 was out of tolerance at 0.4V of a volt difference..."

"Cell module 20 was found to have a possible future fault. Vehicle needs cell module 1 and 20 replaced"

Exact wording on service receipt.

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