In case of dead 12v battery

[SteveDC]

This is not true, the 12V battery will get topped up literally until the HV battery has nothing left in it anymore apart from the bottom buffer and the car goes into safety shutdown.

No electronics in the car can function without 12V.

Topping—not so. My 12 V died on me when the car was parked for about 3 weeks in a heated garage. The car was about 8 months new at the time. My HV SOC was at about 53%. With a low garage ceiling, use of a flatbed was not an option. I called Porsche service for assistance. A guy in a truck arrived and attached jumper cables. We were in the lower level of a commercial building. After creating the requisite amount of carbon monoxide for about 20 minutes, with the truck revving at a high rate, the car still wouldn't turn on. (The truck driver was dispatched pursuant to my call for Porsche roadside assistance. So he was ”official “ in some sense.) Failure.

After he left, I made one last attempt to turn the car on. It did! I immediately drove the car to the dealer and asked to have the 12 V checked, thinking the 12 V would die on me the whole way there. It was ok.

So mystery never solved, and just how and when the HV charges the 12 V, and how many times, remains a frustrating and concerning mystery to me. I wish it were otherwise. Steve

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[69Mach390]

Topping—not so. My 12 V died on me when the car was parked for about 3 weeks in a heated garage. The car was about 8 months new at the time. My HV SOC was at about 53%. With a low garage ceiling, use of a flatbed was not an option. I called Porsche service for assistance. A guy in a truck arrived and attached jumper cables. We were in the lower level of a commercial building. After creating the requisite amount of carbon monoxide for about 20 minutes, with the truck revving at a high rate, the car still wouldn't turn on. (The truck driver was dispatched pursuant to my call for Porsche roadside assistance. So he was ”official “ in some sense.) Failure.

After he left, I made one last attempt to turn the car on. It did! I immediately drove the car to the dealer and asked to have the 12 V checked, thinking the 12 V would die on me the whole way there. It was ok.

So mystery never solved, and just how and when the HV charges the 12 V, and how many times, remains a frustrating and concerning mystery to me. I wish it were otherwise. Steve

Based on when you joined the forum, I take it that this happened years ago?

It’s possible a software update since then fixed this issue.

 

[SteveDC]

Based on when you joined the forum, I take it that this happened years ago?

It’s possible a software update since then fixed this issue.

You are correct. I have MY21. I haven’t had the same experience since that time. If fixed, Porsche could do us the courtesy of telling us they fixed it and telling us the new rules. There are some older comments on the forum saying the HV will do a fill-up 6 or 8 times And then stop.
I still approach the car with trepidation when it has been sitting about 2 weeks, which is often the case. It’s a quality of life thing.

 

[prj]

You are correct. I have MY21. I haven’t had the same experience since that time. If fixed, Porsche could do us the courtesy of telling us they fixed it and telling us the new rules. There are some older comments on the forum saying the HV will do a fill-up 6 or 8 times And then stop.
I still approach the car with trepidation when it has been sitting about 2 weeks, which is often the case. It’s a quality of life thing.

Yeah what you are describing was super widespread back in '21 but there was an update that fixed it.

As said, my MY22 stood in a heated garage for 7 weeks last year without anything plugged in and turned on without a single warning or error.
If you look at the Porsche TSB then it seems normal - they say it should not have any problems for 8 weeks, so if it does, something is deffo broken.

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