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Here is the strange thing that happened to a 7 days old Cayenne turbo eHybrid. We parked it in the garage yesterday and plugged it in to charge. Disconnected the charging before bedtime when it was fully charged. Today we wanted t take it out in the PM and the car was completely dead. Like dead dead, no sign of life. We got road assistance from Porsche to come up to our house and jump start the 12V battery that was completely dead. So in less than 24h the 12V batter discharged. After jump starting and driving car around it is working although it was showing that Airbag system has a system error.
Took it to the Porsche for diagnostics on why it happened.
Questions:
1. Does the 12V batter gets charged when driving on e-power mode that we use mostly to zoom around town. I would assume so.
2. My wife left the keys of the Cayenne in the car overnight. Could that have to do with 12V batter getting discharged as the car though someone is in car?
3. With main battery fully charged, why does the system not boost the 12V battery when it gets low?
4. anyone had similar experience?
Unsure if the 9Y0.2 is changed (google didn't pull up anything) but the 9Y0.1 E Hybrids didn't have an alternator. I believe the HV battery is supposed to keep the 12V charged, and also provide some sort of trickle charger effect when plugged into your EVSE. I had my 9Y0.1 for 4 years and the original 12V never needed changed, have had my S E Hybrid for 2 months with zero issues on 12V battery drain (it is currently not plugged in nightly, as I am driving exclusively in Sport to run in the ICE properly). I would have your service department check this out.
Unsure if the 9Y0.2 is changed (google didn't pull up anything) but the 9Y0.1 E Hybrids didn't have an alternator. I believe the HV battery is supposed to keep the 12V charged, and also provide some sort of trickle charger effect when plugged into your EVSE. I had my 9Y0.1 for 4 years and the original 12V never needed changed, have had my S E Hybrid for 2 months with zero issues on 12V battery drain (it is currently not plugged in nightly, as I am driving exclusively in Sport to run in the ICE properly). I would have your service department check this out.
Thank you for reply. It is in the shop as they are running tests. What you are explaining makes total sense. Given that, something happened and the 12V battery was not kept charged and drained in less than 18h. Will post here with what the shop says.
It should be something about the keys left in the car.
The parasitic draw is normally quite high when the car is unlocked and not in the hibernating state. When you lock the car, the car goes into deep hibernation to reduce the power draw from the battery. The software managing different components of the car to maintain a low current draw is not smart enough, unfortunately.
The manual states it multiple times to leave the car locked at night, without the keys left inside to let the vehicle go into that deep hibernation state. You can still awake the vehicle from the hibernation using My Porsche app from your phone, but you can only do it a couple of times, to limit the amount of reserve consumed from the battery.
the big battery should keep the 12V battery charged unless the big battery gets really really low - my 2021 has a 17.9 kWh raw capacity battery - I've never shoved more than 13.2 kWh into it while charging - so when it's "empty" on the dash that means there is still about 4.5 kWh left -more than enough to run the vehicle and charge the 12V system - will be interesting to see if dealer/service has an actual diagnosis.
there is no alternator but the transmission's EV motor is technically a generator any time the vehicle needs it to provide power - so it's constantly charging the big battery but only to keep it above minimum's - as long as there is residual powering the big battery there should be enough to keep the 12V alive, and start the vehicle with the EV motor in the transmission - the 12V battery in the hybrids (like full TVs) are not a starter battery they are there to wake up the computer that controls the relay to the 400V/DC big battery - so it's just a battery backup to wake up the computer which controls the entire vehicle and can start the ICE motor.
Last edited by daveo4porsche; 08-22-2024 at 08:22 PM.
It should be something about the keys left in the car.
The parasitic draw is normally quite high when the car is unlocked and not in the hibernating state. When you lock the car, the car goes into deep hibernation to reduce the power draw from the battery. The software managing different components of the car to maintain a low current draw is not smart enough, unfortunately.
The manual states it multiple times to leave the car locked at night, without the keys left inside to let the vehicle go into that deep hibernation state. You can still awake the vehicle from the hibernation using My Porsche app from your phone, but you can only do it a couple of times, to limit the amount of reserve consumed from the battery.
Yes, leaving the keys in a new hybrid does not put the car into full hibernation. It can drain the 12V battery because many systems remain active but the high-voltage battery charge is not maintained.
Yes, leaving the keys in a new hybrid does not put the car into full hibernation. It can drain the 12V battery because many systems remain active but the high-voltage battery charge is not maintained.
I do believe leaving keys in the car had something to do with it, but still it is a bad design as main battery which was fully charged could have kept the 12V charged. All the cars we had we always left them unlocked in the garage so this is a surprise event to me…well car is still at Porsche running diagnostics for day 2…
I do believe leaving keys in the car had something to do with it, but still it is a bad design as main battery which was fully charged could have kept the 12V charged. All the cars we had we always left them unlocked in the garage so this is a surprise event to me…well car is still at Porsche running diagnostics for day 2…
As a rule, in hybrids, the high-voltage battery is disconnected after about 15 minutes after the end of the drive.
You don't have to lock the car, just don't leave the keys inside.
Your car probably sat at the dealer's for a long time so the 12V battery was discharged plus the keys left in the car finished the job.
Charging the high-voltage battery does not charge the 12V battery while stationary. If you want to charge the 12V battery, you have to use a regular 12V AGM battery charger. The terminals for charging this battery are under the hood.
According to this tweet from Porsche Great Britain, the HV charger will keep the 12V battery trickle charged. But there’s a catch — if your 12V battery is dead, you can’t charge the HV battery.
2. My wife left the keys of the Cayenne in the car overnight. Could that have to do with 12V batter getting discharged as the car though someone is in car?
Service gave me update and they are keeping the car (over the weekend) for more diagnostics and even potentially replacing the connect module as they claim even with key in the car it should not drain 12V battery so there is issue with the car... Frustrating.
New update from the service department and they are looking into parasitic draw and think they need to replace connect module and potentially something else. I'm scratching my had here on how a 7days 160mi old car can have a "parasitic" draw. I mean it did sit 2 months in the port waiting for CARB certification and then another few days at dealership. just worried someone taking apart all the parts to troubleshoot something that is not needed...
New update from the service department and they are looking into parasitic draw and think they need to replace connect module and potentially something else. I'm scratching my had here on how a 7days 160mi old car can have a "parasitic" draw. I mean it did sit 2 months in the port waiting for CARB certification and then another few days at dealership. just worried someone taking apart all the parts to troubleshoot something that is not needed...
Yes, it's strange that they didn't discover it when the car was at the dealership. It was probably difficult to detect while it was waiting at the port because the car had the software transport mode enabled, in which some of the controllers are totally asleep or operating in power saving mode.
08-20-2024, 08:38 PM
12V battery died on 7days old Turbo eHybrid
