Pt.2: Taycan lets you drive with shorted out battery modules [VIDEO]

[Jasper4S]

Totally off topic, but since @prj and @ct14garage joined the forum we have some interesting threads again. No more depreciation, Porsche stock or other negative news

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[BjörnfromHamburg]

Yes, two big-time contributors to understanding this awesome car (which I still think it is!) and making the taycanforum an interesting place to be!

 

[hifi239]

Hi Cristian, thanks so much for all this excellent information and the video.

First of all, as a EE, when you said "full short" I understood that to mean what we call "dead short," which is zero ohms. You were showing 10Kohms, which would result in about 50mA of current. Not saying that's good, just saying that's not a dead short. Mainly, the 10 Kohms indicates an impending battery failure and is a strong concern, but I'm trying to understand how that energizes the chassis ground, and why, if the contactors are open would make any difference?

Is the below diagram right, where if R1, R2 or both are less than 1Mohm leaking to the case, and therefore to the battery tray? Is the module case and battery tray grounded to the chassis (R4=0?) or isolated? (The US FMVSS 305 specification requires that at least 500 Ω/V (R3, R4 > 250kohm) of isolation resistance be maintained from HV systems to chassis ground.)

 

[hifi239]

Nope, some Taycans arent flagged for ARB6 nor ARB7. But it’s the minority!

Thanks. I expect these are the 2024 ones just before the refresh.

 

[ct14garage]

out 50mA of current. Not saying that's good, just saying that's not a dead short. Mainly, the 10 Kohms indicates an impending battery fai

10 kilo ohm is the minimum Fluke 1508 can display. Don't take it for granted that the isolation is actually 10 kilo ohm I know it's way less than that due to the number shown at the bottom

Based on this measurement I would say actual isolation is between 2,000 Ohm to maximum 5,000 Ohm... Yeah I know exactly 0 Ohms are needed for it be called "dead short" technically...
But in such a case the car wouldn't drive, it would just burn itself.

Then... BYD limits battery isolation to 30 Mega Ohm thresold, Tesla same I believe. Yet are we really discussing whether 0.01 Mega Ohm (as seen in the meter) or even 0.002 Mega Ohm to 0.005 Ohms are acceptable?

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Module case and battery tray are grounded to chassis so battery frame is live.

The contactor opening doesn't magically fix the problem. But with the contactor opened you can't drive nor charge so much harder to cause a thermal event.

 

[ct14garage]

Thanks. I expect these are the 2024 ones just before the refresh.

Nope older cars as well

 

[D00notD00d]

These are the production dates supplied by Porsche to the USA and EU safety authorities - see attached, all up to 1st Feb 2024 in the USA and all up to 4th March 2024 in Europe. The first j1.2 registration in the UK seems to be April 24.
It seems unlikely that both generations were produced in parallel.
If cars built before 4/3/24 have not received a recall notice, it is likely they have been missed. Also now the MyPorsche app includes the recall info, that contract would have to have lapsed. Since Porsche Connect lasts 10 years it should also be possible for Porsche to send recall info direct to the car, but doesn’t seem to do this.
Similarly, OTA updates to the BMS should usually be possible.

 

[frietzak]

These are the production dates supplied by Porsche to the USA and EU safety authorities - see attached, all up to 1st Feb 2024 in the USA and all up to 4th March 2024 in Europe. The first j1.2 registration in the UK seems to be April 24.
It seems unlikely that both generations were produced in parallel.
If cars built before 4/3/24 have not received a recall notice, it is likely they have been missed. Also now the MyPorsche app includes the recall info, that contract would have to have lapsed. Since Porsche Connect lasts 10 years it should also be possible for Porsche to send recall info direct to the car, but doesn’t seem to do this.
Similarly, OTA updates to the BMS should usually be possible.

How can cars be missed if they just need to flag all cars between a certain date?

 

[chun]

How can cars be missed if they just need to flag all cars between a certain date?

Different regulations in each country; at least in Europe.

I believe in USA also, not all states are aligned on car regulations

 

[ct14garage]

Another car that came to the shop with yellow electrical system fault light only and very poor isolation.

Battery frame verified high voltage potential

Monday open up the battery and let’s ser

 

[D00notD00d]

Is ingres from the rain season a factor?

 

[ct14garage]

Is ingres from the rain season a factor?

Sure, but that’s one of the many causes.

It is unrelated to the BMS allowing you to drive with very very poor isolation

 

[AutoX]

These are the production dates supplied by Porsche to the USA and EU safety authorities - see attached, all up to 1st Feb 2024 in the USA and all up to 4th March 2024 in Europe. The first j1.2 registration in the UK seems to be April 24.
It seems unlikely that both generations were produced in parallel.
If cars built before 4/3/24 have not received a recall notice, it is likely they have been missed. Also now the MyPorsche app includes the recall info, that contract would have to have lapsed. Since Porsche Connect lasts 10 years it should also be possible for Porsche to send recall info direct to the car, but doesn’t seem to do this.
Similarly, OTA updates to the BMS should usually be possible.

The only caveat is that the the non sequential box is checked for the VIN affected. So it's possible that not all VIN within the production date is affected.

I just don't see how Porsche could have "missed/forgot" to include some cars otherwise in the recall.

 

[D00notD00d]

The only caveat is that the the non sequential box is checked for the VIN affected. So it's possible that not all VIN within the production date is affected.

I just don't see how Porsche could have "missed/forgot" to include some cars otherwise in the recall.

The EU recall quotes all cars produced 21/10/19 to 4/3/24. In otherwords, all J1.1.
I don’t see how Porsche could know that LG produced some fault free modules that were included in US bound cars produced between 21/10/19 to 1/2/24, but I can’t explain why the VIn range isn’t sequential. Perhaps some have been written off, or are unregistered/otherwise unaccounted for. Some may have been on the cargo ship which caught fire in 2022.
The US recall affects 27,527 cars of which 2% are said to have defective modules. But since previous recalls and their analysis methods were unsuccessful and did not detect all defective modules, and we know that rapid charging above 80% is a trigger to reveal the defect, I don’t know how an accurate estimate could be given.

 

[ct14garage]

Another fire bomb on wheels at the shop. This car has the ARB6 update installed.

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