I joined the Red Circle of Death club

[JIP1080]

Curious which dealer you're servicing at. I'm around the corner from you if the bio is accurate. My 23 GTS ST went in this past Tuesday for the second time in five months for module replacements. Electric Macan for wheels while I wait.

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[rb33gl]

My MY 2022 RWD suffered the same a couple of weeks ago. I got out and locked the car, and it was OK when I got back in again 10 minuted later. It's off the the OPC next week.

The thing I find disconcerting is that you get no forewarning this was going to happen. With an ICE car, you usually get plenty of notice something is going to happen - an oil pressure light, a gearbox whine, some tapping sound. But the Taycan just gives up. Not very Porsche.

Turned out mine needed a software update for the BMS. HV battery was fine.

Only time will tell.

 

[LonePalmBJ]

Curious which dealer you're servicing at. I'm around the corner from you if the bio is accurate. My 23 GTS ST went in this past Tuesday for the second time in five months for module replacements. Electric Macan for wheels while I wait.

Hennessey North Atlanta/Alpharetta. Overall they've done a fine job for me over the last 5 years. That's not to say things didn't take longer than they should have, or that communication was great, but in the balance I have no complaints.

 

[JIP1080]

Hennessey North Atlanta/Alpharetta. Overall they've done a fine job for me over the last 5 years. That's not to say things didn't take longer than they should have, or that communication was great, but in the balance I have no complaints.

Any updates on your car? Month in on mine and "still waiting on parts" 🫤 Hoping you're getting better news.

 

[LonePalmBJ]

Any updates on your car? Month in on mine and "still waiting on parts" 🫤 Hoping you're getting better news.

Good timing. I got a call from my Service Advisor this morning. First update since I brought the car in. They received whatever approval or guidance they needed from Porsche to repair some modules in my battery (as opposed to full replacement) and it's in the queue. He said they only have one bay that can do this kind of repair, and that there were a couple of cars ahead of mine so It's likely going to be a few more weeks, which I interpret as 'two more months'. Not ideal, but at least I have plan, and a Cayenne loaner to get around in.

 

[SergeyIndy]

Good timing. I got a call from my Service Advisor this morning. First update since I brought the car in. They received whatever approval or guidance they needed from Porsche to repair some modules in my battery (as opposed to full replacement) and it's in the queue. He said they only have one bay that can do this kind of repair, and that there were a couple of cars ahead of mine so It's likely going to be a few more weeks, which I interpret as 'two more months'. Not ideal, but at least I have plan, and a Cayenne loaner to get around in.

Terrible situation and such a long wait. My dealer turns this around much faster, as they remove and ship the battery, requiring a special shipping container that they have several of, and then get it back. This is much faster than doing it at the dealership based on the wait you are describing.

 

[JIP1080]

Good timing. I got a call from my Service Advisor this morning. First update since I brought the car in. They received whatever approval or guidance they needed from Porsche to repair some modules in my battery (as opposed to full replacement) and it's in the queue. He said they only have one bay that can do this kind of repair, and that there were a couple of cars ahead of mine so It's likely going to be a few more weeks, which I interpret as 'two more months'. Not ideal, but at least I have plan, and a Cayenne loaner to get around in.

Glad there is an update. I just got a notice that climate conditioning finished just now, which is either moving my car out of the way, or starting to get ready for the work. Hoping for an update soon based on that notification.

 

[JIP1080]

@LonePalmBJ hope you're getting better news. Just got word that best case is another month. SA is really good with comms, up front and willing to give an honest assessment, and generally just a good person to work with. So when he says another month+ I'm inclined to believe him. Still though, can always hope for an "under promise over deliver" scenario

 

[ZenicaNC]

So I had the yellow circle 2 months ago. Brought it in, they did an update and it cleared the error. Well, 3 weeks ago that error came back, with a friend. Chassis Error. Brought it in a few days ago and they let me know Porsche told them to replace the high voltage cells. I thought the new procedure was a complete pack replacement, not this nickel and dime shit with replacing cells.

 

[JIP1080]

So I had the yellow circle 2 months ago. Brought it in, they did an update and it cleared the error. Well, 3 weeks ago that error came back, with a friend. Chassis Error. Brought it in a few days ago and they let me know Porsche told them to replace the high voltage cells. I thought the new procedure was a complete pack replacement, not this nickel and dime shit with replacing cells.

It's been individual module replacements both times for me. About to be a Ship of Theseus situation.

 

[ZenicaNC]

It's been individual module replacements both times for me. About to be a Ship of Theseus situation.

My SA just confirmed. They're replacing just 5 of the 33 high voltage cell modules. Porsche told them test afterward and report the results.

I guess all those battery operated electronic devices I've had over the years that cautioned in the manual to never mix old batteries with new ones was just fear mongering? or in a pact with Energizer/Duracell to promote the purchase of new batteries.

 

[BjörnfromHamburg]

Your battery will work fine.
It's just a fact, that overall SoH will not improve with new modules, as the lowest SoH modules will set the overall SoH.

With an all new battery SoH will be "as new".

 

[ZenicaNC]

Your battery will work fine.
It's just a fact, that overall SoH will not improve with new modules, as the lowest SoH modules will set the overall SoH.

With an all new battery SoH will be "as new".

I asked AI (yea, go ahead, gimme that look) about mixing new and old lithium batteries.
This is what it had to say, which is consistent with what I've read and have been told about battery chemistry. What information does Porsche have that the internet doesn't?

why should new and old lithium batteries not be mixed

Mixing new and old lithium batteries creates dangerous electrical imbalances that can overheat, damage cells, and shorten the lifespan of the entire pack. The newer battery is forced to “carry” the older one, which stresses both and can lead to swelling, leakage, or even thermal runaway.


Why Mixing New & Old Lithium Batteries Is Unsafe
1. Capacity Imbalance

• Older lithium cells hold less charge.
• When paired with a new cell, the system’s usable capacity drops to the weakest battery.
• The newer battery is overworked trying to match the older one’s lower output.

2. Uneven Charging & Overheating

• Older cells reach full charge sooner; newer cells lag behind.
• Charging based on total pack voltage can overcharge the old cell or undercharge the new one.
• This mismatch generates excess heat, accelerating degradation.

3. Voltage Mismatch → Dangerous Circulating Currents

• Newer lithium packs sit at a higher voltage than aged ones.
• When connected together, the higher‑voltage pack “force charges” the lower‑voltage pack.
• This creates circulating currents that can spike to extremely high levels—far beyond what the cells are designed to handle.
• Result: internal damage, melted wiring, or catastrophic failure.

4. Increased Risk of Thermal Runaway

• Heat + internal damage = a setup for swelling, venting, or fire.
• Lithium cells are especially sensitive to overcurrent and overtemperature conditions.

5. Faster Degradation of the New Battery

• The new battery compensates for the old one’s weakness.
• This accelerates wear, reducing its lifespan dramatically.

Practical Takeaway
If you’re building or maintaining anything with lithium cells—power tools, solar storage, e‑bikes, or even small electronics—always use matched sets:

• Same age
• Same capacity
• Same chemistry
• Same manufacturer
• Same cycle history

Mixing them isn’t just inefficient—it’s a real safety hazard.

If you want, I can walk you through how to safely replace or parallel lithium cells in a pack, or help you evaluate whether a specific battery setup is safe.

 

[BjörnfromHamburg]

This does not apply because random Lithium cells don't have a bms, battery management system.

 

[websterize]

“Action: If the previous high-voltage battery needs to be replaced, replace it with a high-voltage battery from model year 2025 onward.” — https://static.nhtsa.gov/odi/tsbs/2025/MC-11015164-0001.pdf

What do Service Advisors say when you show them this document? What is the procedure for determining the degree to which a high-voltage battery needs to be replaced? It seems that some owners have had only a few modules replaced, while others have had all of them refreshed. How many modules have to fail to get a fresh pack?

As a new owner of a CPO 2020 4S, I follow these discussions with great interest, and with empathy toward the owners. This must be so frustrating. While my car’s battery pack is currently stable, five of its modules have been replaced in the past, and I want to be ready to make a case should I get the .

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