Taycan Problems are overwhelming an otherwise great car

[Scandinavian]

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.

Here is a link to an article about the battery in the Taycan. 33 modules with 12 cells in each according to the document .

https://media.porsche.com/mediakit/taycan/en/porsche-taycan/die-batterie

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[Dr Bob]

Here is a link to an article about the battery in the Taycan. 33 modules with 12 cells in each according to the document .

https://media.porsche.com/mediakit/taycan/en/porsche-taycan/die-batterie

Peter, thanks for that link. That tells me what the set up is. The key data is the 168S * 2P with 396 cells altogether.

So we have a battery bank comprising 33 cell modules. Each cell module with therefore be a 6S *2P config, ie 6 cells in series and each of those paralleled with another cell. It is a bit confusing that the 610V to 835V range is achieved with 168 cells in series as that suggests the average cell voltage is over 4.0V which seems high for a normal LiFePO4 cell. My calcs then say that each cell has a capacity of 64Ahr.

"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.

Vim, Using the above info from Peter, Cell pouch 5 in module 1 will mean the two paralelled cells (pouch 5) out of the first of the 33 modules. The key here is that the 0.4v delta is a cell voltage reading (in my previous post above I was talking about cell voltage rather than module voltage - module voltage is likely to be of the order of 24V). That 0.4V delta is huge and means that the cell will reach 0.0V with most of the other cell pouch voltages in the middle of the low voltage knee when at the low end of the SoC. That is a good example of the bank being well out of balance due to one cell pouch at the bottom end in a top balancing regime.

 

[Scandinavian]

@Vim Schrotnock
I made an update to my battery here https://www.taycanforum.com/forum/threads/another-my-2020-turbo-bites-the-dust.17088/post-269383

Car is back and all my cells are equally balanced, but very strange SoH and battery capacity??

I will check after driving the car more next week!

 

[Dcgator]

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. ?

My MY2020 Taycan Turbo has this exact issue last year 10/22. Loss of range then car became inoperable. 5 weeks and two HV battery cells replaced later, I had my car back. It was back to normal until this week, when the exact symptoms returned. It is currently at the dealership undergoing diagnostics, which I expect will show a similar problem.

This is the best driving and least reliable car I have ever owned. Also the first car that I have ever leased (was concerned about new tech and this scenario). I plan to reach out to PCNA and seek early lease termination. It is currently scheduled to end 2/2024.

 

[Dr Bob]

My MY2020 Taycan Turbo has this exact issue last year 10/22. Loss of range then car became inoperable. 5 weeks and two HV battery cells replaced later, I had my car back. It was back to normal until this week, when the exact symptoms returned. It is currently at the dealership undergoing diagnostics, which I expect will show a similar problem.

This is the best driving and least reliable car I have ever owned. Also the first car that I have ever leased (was concerned about new tech and this scenario). I plan to reach out to PCNA and seek early lease termination. It is currently scheduled to end 2/2024.

Dcgator,

Interesting info.

I assume you mean they replaced 2 cell modules rather than 2 cells?

It is quite disturbing to hear of these replacement module issues and especially when you have a handful of people with the same issue on the same thread.

The problem is either going to be that the problem modules have cells in them that were not perfect from the start or that the problems have been caused by the charging/discharging regime. In this case maybe you have 4 bad cells of which 2 went bad a year ago and now the other two have gone.

I'd like to think this is a cell quality control issue and the cells are failing because of an inherent fault from the factory- although almost certainly exacerbated by the charging/discharging regime. Whilst it seems to be happening a lot, I guess a number people with an issue like this would migrate to this forum so maybe there are only a couple of dozen cases in the tens of thousands of Taycans sold. Hopefully then most of us will not see the same problem and my turn is not coming soon.

I like to think the problem is not due to good cells being damaged by the charging/discharging regime. Continued charging when the cells are at their critical voltage can irreversibly damage cells. That is a fact. Fast charging at temps below freezing can irreversibly damage cells. That is a fact. Top balanced cells can have an in-balance at the bottom that can take a cell to 0V and cause irreversible change.That is a fact. Charging and discharging cells can damage them. Charging rates are important. If you have a battery with a capacity of 90kWh and charge at 90kW, then that is a charge of C1. If you charge at 9kWh, that is C/10. If you charge at 270kWh, that is 3C. Charging (or discharging) at 3C or 4C puts one heck of a strain on a battery so could easily cause issues with 'not quite right' cells. The fact that 10's of thousands of Taycans dont have serious battery issues (module failure) says that a good battery should be able to withstand what we throw at them so maybe the issue is poor initial QC. One variable though is temperature and all bets are off when we start talking about temps getting up to 45-50°C. Chemistry works faster as you go up in temp (a simplistic rule is reactions go twice as fast for every 10°C you go up) and other reactions start as you reach certain temperatures.

It looks like these problems are few and far between, but that is no comfort to those who have the issue.

Please keep us posted on the outcome of this latest battery problem.

 

[Scandinavian]

Would be interesting to get the full picture of failure rates though. I know of a couple of cars from my Porsche Centre that have had these issues. And they re not one of the places that sell so many Taycans. The fact that there now is a queue to get batteries repaired here is not a good sign either. This could of course be both capacity for repairs but also lack of spare parts and supply issues?? The wait time for this could be up to 4 months here?

Let’s hope this is just a small number of cases. Time will tell and I am going on some quite long Nordic trips over December January. Temperatures are known to be down to minus 20 C at these places then.

 

[Sace]

I like to think the problem is not due to good cells being damaged by the charging/discharging regime.

I would like to think the same. But realistically I guess the cells are a pretty standard cell - Why is Porsche having so much trouble with them? It's most likely the same cells used in other brands too.

Maybe you are right that it's a combination of the HV system implementation and cells that are a bit off.

I live in Denmark which is a small country and I have seen the issue mentioned a few times here too. The total number of Taycans registered here is around 1000 since 2020.

 

[Caraholic]

Well it seems mine needs 12 cells replaced as well on top of the high voltage charger and booster. What I am not sure of is if all 12 bad cells are in one cell module or more. The wait continues.

 

[Dcgator]

They have decided to replace my entire battery. The part should be her this week and apparently, it’s only a few hours of labor. PCNA opened a case at my request, but was waiting on diagnostics. A few have few a months left on my lease. I am hoping PCNA will offer early termination, based on the lack of reliability of my vehicle. It has been down 11-12 weeks of the 34 months of ownership.

 

[PNWTaycan4S]

Looks like in the U.S. Porsche USA now has a stock of HV batteries. From diagnosis to full battery replacement took 12 days on my 2020 4S+ this month. Quite a bit more range too with the new battery.

I was considering a switch to a GTS but decided to buy an extended Porsche warranty and keep the 4S+ for several more years. New HV battery continues under the original 8-year/100,000 mile warranty. I'll get a new Taycan when Porsche switches to NACS and does a full new update, instead of the current refresh.

 

[Vim Schrotnock]

They have decided to replace my entire battery. The part should be her this week and apparently, it’s only a few hours of labor. PCNA opened a case at my request, but was waiting on diagnostics. A few have few a months left on my lease. I am hoping PCNA will offer early termination, based on the lack of reliability of my vehicle. It has been down 11-12 weeks of the 34 months of ownership.

I have had exactly the same problem you initially had, with the replacement of two modules. My battery capacity is down to 79kWh at this point, and I'm being told that it will take three weeks of charging from 10-15% to 100% for the battery to 'adapt' to the new modules. Did you have this same experience? i.e. did you see minimal improvement with the replacement of the two modules, and did you see your battery capacity improve over time? I'm a bit skeptical here, but I will defer to the experts and follow the recommended charging protocol. Here is the text from the technician, after I was told to charge/discharge from 10-15% to 100% three times, but evidently it needs three weeks:

Our last correspondence we all agreed that he would follow a specific discharge and charge cycle for 3 weeks. The capacity adaption will not be complete after 3 drives. It takes time for the new capacity to adapt after introducing new modules into the rebuilt battery.

 

[Dcgator]

I’m not aware of what my battery capacity was after the replacement of the cells. Originally my car would display a range of 250 miles when charged to 100%. Following an update approximately one year ago the range increased to 275 miles. Shortly there after the battery cells failed.

After the repair, my range return to the original 250 miles. I was never made aware of the discharge and recharge three cycle process that you described. However, I did not notice any significant changes in the displayed range from the time of the repair until the most recent failure.

 

[Tooney]

My MY2020 Taycan Turbo has this exact issue last year 10/22. Loss of range then car became inoperable. 5 weeks and two HV battery cells replaced later, I had my car back. It was back to normal until this week, when the exact symptoms returned. It is currently at the dealership undergoing diagnostics, which I expect will show a similar problem.

This is the best driving and least reliable car I have ever owned. Also the first car that I have ever leased (was concerned about new tech and this scenario). I plan to reach out to PCNA and seek early lease termination. It is currently scheduled to end 2/2024.

Could you describe again "the exact symptoms returned"? I want to be clear about what you experienced the second time.

 

[Vim Schrotnock]

Well, it's been about a 4 month journey, but the replacement of my two battery modules seems to have worked. I've been following the 'balancing' protocol outlined by the Porsche battery technician, and it works - my battery is now back to 'good as new', or possibly better, after the module replacement. I was getting 236mi on 85% charge before this all started, and today (in the winter vs summer), here's my reading (all at normal setting):

 

[Lefty8235]

This thread was insightful, but I didn’t get through every comment.

Curious, are these issues persistent with the 23 and 24 model years as well or are they lingering issues with the earlier years?

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