Taycan 12V drain issues - caught in the act?

[Taycanturbolondon]

I`m experiencing the same (i need the pin for safety in shared garage).
I thought the car was able to sense the Porsche connect charger, making the charger only work on my car without the pin.

Maybe we need the new update (late feb.)?

i even took my charger upstairs to my apartment so i could connect to wifi and check for any updates- none. i couldnt sign into my Porsche Connect account on my charger, it kept asking me to scan the QR code, i had from no idea where in the app that facility is

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[Scandinavian]

i even took my charger upstairs to my apartment so i could connect to wifi and check for any updates- none. i couldnt sign into my Porsche Connect account on my charger, it kept asking me to scan the QR code, i had from no idea where in the app that facility is

If you have an iPhone (> ios11), you have three choices
1. use the camera
2. use the Connect app see photo below
3. use any app that can scan QR codes!

The same scan option in the Connect app works with charging at Ionity

 

[Iben]

I don't have the last option "avtivate plug & charge".
Maybe you have newer software than I have?

 

[feye]

I don't have the last option "avtivate plug & charge".
Maybe you have newer software than I have?

I checked here first to safe time in the car.

I am pretty sure I do not have this in my 2020 model.

 

[chrisk]

I don't have the last option "avtivate plug & charge".
Maybe you have newer software than I have?

Plug and Charge is not yet available in 2020 models. It is a feature for the public DC fastchargers to find and bill your account without using a mobile app or a card so it is certainly not relevant to home charging or the 12v drain problem described in this thread.

 

[NC_Taycan]

Some filler comments:
1) Yes there have been 12V deaths while connected to the PMCC (myself included)
2) There is not a lot of communication between the PMCC and car. The PMCC tells the car the available charging current and the car can stop and start the charging session. There is the possibility of limited additional communication over J1772 (AC charging) but it is not clear if the PMCC was designed to support this (could be hardware limitation, could be software limitation).

DC is a different animal - plenty of two-way communication built into the combo port.

 

[daveo4EV]

well simply based on the PMCC knowing the difference between when the car is done charging and is delaying charging (flashing blue lights) there is clearly communication going on beyond the strict J-1772 protocol specification.

I’m pretty convinced Porsche has some out-of-band communication attempts from the vehicle to the PMCC - what I can not say for certain is if these communication attempts are what makes it confused when talking to other chargers and potentially leads to software bugs draining the 12V system

but it’s a reasonable guess

 

[NC_Taycan]

I think it's more than a reasonable guess. There's just not a lot of communication going on. Here is the basic (nothing above J1772) series of steps:

1) PMCC powers on (either because you turned it on or because you connected your car)
The mechanical connection of the plug to the car completes a proximity circuit that allows the PMCC to know there is something connected and allows the car to know there is something plugged in.

2) PMCC initiates pilot signal to the car
This signal is just a pulse width modulated (PWM) square wave. The charging power is communicated to the car by varying the duty cycle.

3) Car's charging controller wakes up and tells the charger what to do by changing the resistance applied to the pilot signal (which the PMCC can read as one of four commands plus a don't do anything state). At the PMCC there are a total of six states:

a) Stand-by (no vehicle connected)
b) Vehicle connected (idle state)
c) Charge
d) Charge only if in ventilated area
e) Charging completed
f) Error (signaled by vehicle)

The connected state does NOT require the vehicle-side charging controller to be powered up (which is why the charger can remain powered up waiting for the vehicle while the vehicle is asleep). This is the flashing lights state on the PMCC.

The theory (from the Taycan specialist at my service center) was that either or both of the following are happening when the 12V dies:

1) the charging completed handshake was failing to shut down the pilot interface. If the charger wakes that pilot interface back up then the vehicle interface also wakes back up and consumes 12V power while awake, but since nothing needing the HV battery is used, the HV battery doesn't come on until the 12V battery requests a re-charge. There is a limit on the number of times the HV system will accept that recharge request before refusing to recharge the 12V. I don't know why, but I can guess that when this count limit was set, the designer never thought it would hit that limit. IMHO, this is what @daveo4EV captured.

2) the vehicle was waking the charging interface up because of some math associated with SOC and the charge limit/target from a timer led it to believe it had something to do. IMHO this is how I killed my 12V battery the one time I have done so (changed a timer while the car was plugged in).

Note there are newer protocols with additional side-band communication via the pilot signal. This is how the vehicle communicates with a Porsche Home Energy Manager via the PMCC. Once HEM support is disabled in the PMCC I don't think there is any communication happening beyond the basic stuff outlined above.

 

[chrisk]

Porsche TSB for the 12v drain issue dated Dec 15th. It is a very interesting read!
https://static.nhtsa.gov/odi/tsbs/2020/MC-10185117-0001.pdf

Copying from the TSB:

Information:
The 12-volt vehicle electrical system battery may be discharged in conjunction with the high-voltage charging process on Taycan vehicles. This is caused by the fact that the communication between the high-voltage charger and the vehicle is maintained under certain conditions. This results in increased current consumption of the 12-volt battery.

Introduction:
A software solution is currently being developed and is expected to be available in the first quarter of 2021

Suggested Actions to reduce likelihood of 12v b. drainage till the fix is ready

1. When possible, disconnecting the high-voltage charger from the vehicle after the charging process is completed will greatly reduce the likelihood of errors and a discharged 12V battery.
2. Deactivate the Power Line Communication (PLC) of the Porsche Mobile Charger Plus / Porsche Mobile Charger Connect via the web application using the internet browser (TSB has instructions)
3. Do not use the ‘Preferred Charging Times’ function of 'Profile charging'.
4. An active "charging with timer" function requires repeated communication between the charging hardware and the vehicle. This communication may result in a discharged 12V battery.
5. Instruct customers to wait until the charging process is confirmed by the vehicle after connecting the charging cable (green light).
6. If customers require emergency charging on 120v supply equipment, ensure the charging current is set to no less than 8amps to prevent vehicle communication errors.

 

[feye]

2) There is not a lot of communication between the PMCC and car.

Plug & Charge is part of ISO15118 and is possible on both DC and AC as long as the wallbox is supporting it.

The Porsche Charger is supporting this, but currently only with the 11kW onboard charger. For the 22kW onboard charger, the software need to be fixed and should be ready at the end of May 2021.

I checked my MY2020. It does not have the option. But then I have not received any software update. I put this on the list, for my next dealer visit.

 

[feye]

Porsche TSB for the 12v drain issue dated Dec 15th. It is a very interesting read!
https://static.nhtsa.gov/odi/tsbs/2020/MC-10185117-0001.pdf

Thank you! This really explains it.

 

[KensingtonPark]

Does this mean that this shouldn't happen if you are connected to a non-Porsche EVSE, such as a JuiceBox? I had not appreciated that everybody who had the problem were using the Porsche EVSE. I myself have not yet unboxed the Porsche EVSE.

 

[chrisk]

Does this mean that this shouldn't happen if you are connected to a non-Porsche EVSE, such as a JuiceBox? I had not appreciated that everybody who had the problem were using the Porsche EVSE. I myself have not yet unboxed the Porsche EVSE.

It can happen with any charger and the risk is higher if you use timers.
The OP of the other thread about the 12v saga was using a ChargePoint.

 

[NC_Taycan]

I don't necessarily agree that the risk is higher if you use timers. I also don't disagree. I can only share my story. I have been using preferred charging times (in the profile for my home) and a timer (set to 85% with the departure time set when lower cost electricity ends) since April and have had only one occurrence of the 12V battery death, and that was coincident with me changing the parameters of a timer while the vehicle was connected.

 

[daveo4EV]

I think the good news/bad news here is that Porsche is on the case - with bulletins like this it means they are aware they have some issues - and the general descriptions match the kinda gestalt of what we've all been experiencing - something to do with charging cause cause the 12V to get drained - and now Porsche has stated they have some recommendations to mitigate the situation and seem to imply a software update might be forth coming (schedule probably longer than either Porsche or the Taycan community would like)…but it does seem to be progress to me...

the question for me isn't has porsche found and fixed some issues and will there be an update? no question there is going to be an update that chips away at this problem and progress is progress....

the question for me is have they found enough problems and fixed enough that the 12V issues will be "fixed" for the 99.9999% case - having done software long enough you can never say for sure that you've fixed every problem, but you can certainly move any remaining cases of problems into the statistically insignificant category such that it effectively doesn't matter...

while I'd be gratified for some improvements, I'm concerned all we're doing is sweeping some problems out of the way so that we can then finally get down to any remaining problems - this is a common problem with software - fix one class of problems, and what is left is another class of problems you couldn't see or encounter until the previous set was fixed…

time will tell and I'll look forward to the update…

bets on OTA or dealer visit?

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