Don Breaks His Taycan - The Saga of the 12v Battery

[Miwa]

Or the wallet itself may be RFID blocking.

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[r553]

My Cayenne Comfort access fob does not like to be in the same pocket as my cellphone. No workee.

 

[evanevery]

Don (@louv) has done a very meticulous and disciplined job of trying to determine the conditions which cause what is believed to be a 12V battery drain which ultimately kills the battery. This was anticipated to be fixed in one of the recent software update campaigns. (You know, the OTA updates you must bring your car to the dealer to have applied?)

So, for those who haven't been following along, here is quick summary of the POSSIBLE sequence of events which cause the 12V battery to be depleted (thanks Don!): The car is put on charge, the user contacts it via Porsche Connect to adjust some charging settings, the PCM starts up and never shuts off thereby draining the 12v battery. (I think that's a fairly accurate summary)

Anyway, I had something interesting happen yesterday which might help add to our observations.

- So, my car is on the charger in the garage. I have set my 85% "minimum" charge in my default profile. (You know, the "minimum" charge which should actually be called a "maximum" charge?)

- I've had my car only a couple of hours so I want to check in on the vehicle to confirm connectivity using the Porsche Connect Web and App (Android). I use them both. The connectivity is horrible and slow and unreliable. The user interfaces in both environments make me want to tear my hair out. I do ultimately manage to get a connection using both and I'm looking at the projected charge completion of 9PM the NEXT day! This can't be right so I'm checking the charging rate and level (via app and web). I notice my "Allgemein" (Really?) profile is set correctly (85%) but I begin trying to "shake things loose" to get the proper completion time display. I go back and forth between my :allgemein" profile and Direct Charge. Bottom line, the date and time never get set correctly. Anyway, the point here is that I did make some changes to my charging settings via the app.

- So, I'm back out in the garage with the pass door open, laying in the pass footwell examining that little cavity under the console to find the best way to design a nice 3D printed support to hold a RAM mount for my phone. The car is happily charging and it is turned off (although the pass door is open). I'm probably poking around for 20 minutes or so and all of a sudden, I hear some music start playing in the car! The car is OFF (as is the dash and console) but this music starts. All I see on the center of the dash is one small spinning blue circle, but the music starts up all by itself. I realize its my music and its playing off my USB device.

- What I realize, is that this unsolicited system start up has happened at the exact time that my car hit its set charge point (85%). (You know, the "Minimum" charge?) I just happened to be crawling around the inside of the car (turned off) when it reached the charge point I set in my default ("allgemein") profile.

- An interesting point to note is that I have taken delivery less than 12 hrs ago and my dealer has assured me on several occasions that all service campaigns have been applied. So why is my PCM starting up all on its own when the car is turned off? Could it be it knew I was crawling around inside and though I might appreciate hearing some music? I kinda think NOT...

Perhaps, this is exactly the unanticipated/Invisible PCM startup that was first proposed? Perhaps it occurs exactly when the car hits its set charge level? ...and more importantly... Perhaps its not truly fixed?

 

[louv]

Don (@louv) has done a very meticulous and disciplined job of trying to determine the conditions which cause what is believed to be a 12V battery drain which ultimately kills the battery. This was anticipated to be fixed in one of the recent software update campaigns. (You know, the OTA updates you must bring your car to the dealer to have applied?)

So, for those who haven't been following along, here is quick summary of the POSSIBLE sequence of events which cause the 12V battery to be depleted (thanks Don!): The car is put on charge, the user contacts it via Porsche Connect to adjust some charging settings, the PCM starts up and never shuts off thereby draining the 12v battery. (I think that's a fairly accurate summary)

Anyway, I had something interesting happen yesterday which might help add to our observations.

- So, my car is on the charger in the garage. I have set my 85% "minimum" charge in my default profile. (You know, the "minimum" charge which should actually be called a "maximum" charge?)

- I've had my car only a couple of hours so I want to check in on the vehicle to confirm connectivity using the Porsche Connect Web and App (Android). I use them both. The connectivity is horrible and slow and unreliable. The user interfaces in both environments make me want to tear my hair out. I do ultimately manage to get a connection using both and I'm looking at the projected charge completion of 9PM the NEXT day! This can't be right so I'm checking the charging rate and level (via app and web). I notice my "Allgemein" (Really?) profile is set correctly (85%) but I begin trying to "shake things loose" to get the proper completion time display. I go back and forth between my :allgemein" profile and Direct Charge. Bottom line, the date and time never get set correctly. Anyway, the point here is that I did make some changes to my charging settings via the app.

- So, I'm back out in the garage with the pass door open, laying in the pass footwell examining that little cavity under the console to find the best way to design a nice 3D printed support to hold a RAM mount for my phone. The car is happily charging and it is turned off (although the pass door is open). I'm probably poking around for 20 minutes or so and all of a sudden, I hear some music start playing in the car! The car is OFF (as is the dash and console) but this music starts. All I see on the center of the dash is one small spinning blue circle, but the music starts up all by itself. I realize its my music and its playing off my USB device.

- What I realize, is that this unsolicited system start up has happened at the exact time that my car hit its set charge point (85%). (You know, the "Minimum" charge?) I just happened to be crawling around the inside of the car (turned off) when it reached the charge point I set in my default ("allgemein") profile.

- An interesting point to note is that I have taken delivery less than 12 hrs ago and my dealer has assured me on several occasions that all service campaigns have been applied. So why is my PCM starting up all on its own when the car is turned off? Could it be it knew I was crawling around inside and though I might appreciate hearing some music? I kinda think NOT...

Perhaps, this is exactly the unanticipated/Invisible PCM startup that was first proposed? Perhaps it occurs exactly when the car hits its set charge level? ...and more importantly... Perhaps its not truly fixed?

Wow. Very interesting. Nice catch. My car goes in on Monday to get three repair campaigns addressed. It will be there at least a week. Afterwards, I can retest. I’ll see if I can reproduce your symptom as well.

 

[Reg]

Don (@louv)

- What I realize, is that this unsolicited system start up has happened at the exact time that my car hit its set charge point (85%). (You know, the "Minimum" charge?) I just happened to be crawling around the inside of the car (turned off) when it reached the charge point I set in my default ("allgemein") profile.

Did you also set the timer profile to do the preheat/precool of the car? I wonder if when it does that if it also has the music enabled to play? Just an idea.

 

[evanevery]

Did you also set the timer profile to do the preheat/precool of the car? I wonder if when it does that if it also has the music enabled to play? Just an idea.

Nope. No Timers. No Preheat/PreCool. I like it simple.

I just changed the "Minimum Charge" to 85% in the default ("Algemein") profile from inside the car. For some reason it was set to 25% when I took delivery. Probably explains why my car wasn't fully charged...

I wouldn't even have tried to change anything with the App other than the STUPID software was indicating it would not be fully charged (85%) until THE NEXT EVENING. Apparently, they have TODAY and TOMORROW confused! The App said 7:30 PM Tomorrow when it should have said 7:30 PM Today. Anyone want to bet they didn't do their GMT date conversion correctly? (As it would have been TOMORROW in Germany...) Ugh! Who wrote this crap? Who TESTED it? (...apparently US!)

 

[Singularity]

Usually, at least with my Taycan, it will start itself up by itself if I'm just sitting in the car with my keys in my pocket. No need to push the start button. Sometimes this does not work and I need to press the button. But 75% of the time it starts by itself. Which is nice.

So, I'm just wondering here if your activity in the car, with your keys in your pocket (?), was enough to trigger starting the car. And the charging hitting the "minimum" was just a coincidence?

This is just an idea which is good to rule out in order to be able to say that it's actually starting up totally by itself like that. Very interesting nonetheless.

 

[evanevery]

Usually, at least with my Taycan, it will start itself up by itself if I'm just sitting in the car with my keys in my pocket. No need to push the start button. Sometimes this does not work and I need to press the button. But 75% of the time it starts by itself. Which is nice.

So, I'm just wondering here if your activity in the car, with your keys in your pocket (?), was enough to trigger starting the car. And the charging hitting the "minimum" was just a coincidence?

This is just an idea which is good to rule out in order to be able to say that it's actually starting up totally by itself like that. Very interesting nonetheless.

Nope! The car didn't start itself as the Displays never came alive... ...and the keys were outside the car anyway...

NONE of the displays had any info on them other than a very small spinning circle in the center of the main middle display above the center console. (The one in the center of the dash)

 

[jetbox]

Nope! The car didn't start itself as the Displays never came alive... ...and the keys were outside the car anyway...

NONE of the displays had any info on them other than a very small spinning circle in the center of the main middle display above the center console. (The one in the center of the dash)

You can hit the audio button on the lower display and it will start the music ( and you get a little spinning circle on the centre screen) with all the rest of the power and screens off. Did you hit that button by chance?

 

[evanevery]

You can hit the audio button on the lower display and it will start the music ( and you get a little spinning circle on the centre screen) with all the rest of the power and screens off. Did you hit that button by chance?

Not to my knowledge. I was laying through the pass door and into the footwell. I was working in the little cavity on the UNDERSIDE of the console (nothing with the top side)... Its not impossible but I don't think so...

 

[Henry Porter]

This morning I experienced the same with my Taycan Turbo. It was completely dead. (I know that I had altered the charging setting on the app during the night before). I read through all 24 pages of this thread after I called for assistanse. When the assistance came, I could guide him through the steps to opening the hood and charge the 12 V battery. However the strange thing is that when the battery charger was connected it only took a few seconds before the car woke up and I went for a short drive. The voltage on the 12 V battery read 13,9 V. So, I wonder, was the 12 V battery really low on voltage, or was it a software glitch that made the car “think” it was low? I am not sure my question makes any sense , but anyhow. An hour later I drove the 120 miles home without any problems.

 

[louv]

This morning I experienced the same with my Taycan Turbo. It was completely dead. (I know that I had altered the charging setting on the app during the night before). I read through all 24 pages of this thread after I called for assistanse. When the assistance came, I could guide him through the steps to opening the hood and charge the 12 V battery. However the strange thing is that when the battery charger was connected it only took a few seconds before the car woke up and I went for a short drive. The voltage on the 12 V battery read 13,9 V. So, I wonder, was the 12 V battery really low on voltage, or was it a software glitch that made the car “think” it was low? I am not sure my question makes any sense , but anyhow. An hour later I drove the 120 miles home without any problems.

All of what you say sounds perfectly “normal” for this failure. Very soon after you plug in the charger, the voltage of the 12v system will be high enough to trigger the car to wake up, at which point the High Voltage battery will take over the charging of the 12v battery. Then all is well.

Does your car have the new 12v battery and latest software?

 

[Henry Porter]

All of what you say sounds perfectly “normal” for this failure. Very soon after you plug in the charger, the voltage of the 12v system will be high enough to trigger the car to wake up, at which point the High Voltage battery will take over the charging of the 12v battery. Then all is well.

Does your car have the new 12v battery and latest software?

I don’t know. My car was delivered June 24. But it is normal that the 12V battery is fully loaded instantaneously?

 

[louv]

You should ask your Service Advisor. If the car has all the updates then they might not have fixed the bug(s). In any case, be sure your service adviser reports the event to Porsche.

I suspect that the voltage you were seeing was actually the “charging” voltage coming from the DC-DC Converter. If I recall my EE classes correctly, you can’t actually measure the battery’s voltage while it is being charged; what you actually get is the charging voltage. You have to stop charging to get the battery’s true voltage.

 

[taycantom]

You should ask your Service Advisor. If the car has all the updates then they might not have fixed the bug(s). In any case, be sure your service adviser reports the event to Porsche.

I suspect that the voltage you were seeing was actually the “charging” voltage coming from the DC-DC Converter. If I recall my EE classes correctly, you can’t actually measure the battery’s voltage while it is being charged; what you actually get is the charging voltage. You have to stop charging to get the battery’s true voltage.

As a practicing EE, this is correct. If the charger is connected to the posts and is actively driving 13.9V, and if the display is based on the post voltage, then you’d see 13.9V at that time.

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