Excessive drainage of 12v battery for 2025 Macan EV. Anybody experience this?

[MacanEVOwner]

Baseline on my car:
- Car is a 2025, and is about 9 months old
- Has no external hardware e.g., camcorder, etc attached
- Does NOT have the latest software update that many are reporting affects being able to charge their HV battery at home.
- Garaged every night.
- Macan 4S.

Symptoms:
- First noticed that the proximity sensor on my car was not working, or did not open the side mirrors…standing right next to the door handle.
- When door opened, and before I get in the driver’s seat, the 12v battery reads between 11.8v-12.1v after sitting overnight (12+ hours with no activity on the car, ie, not using the app or the key fob.

Observations:
- I attached an Antigravity battery monitor (draws less than 1 mA) system to record the battery history. It was there that have driving for 30 minutes and then letting it sit overnight night, the car slowly dropped from about 12.5v to about 12.0v. The interesting part was that every hour of the voltage scan, showed a momentary spike/drop in the voltage Before returning to it’s steady state voltage.
- If I did NOT interaction with the car by trying to start it, for a period of more than 24 hours, I observed that the 12v battery voltage dropped to about 11.7v where I observed the 12v battery being connected to the traction battery to re-charge it, ie, large positive jump in the voltage level…to about 13.5v. It only stayed connected for a few minutes before the 12v battery voltage level began to slowly decay once more. If I continued to do nothing, the process repeated itself. See attached image.

Attempted remedy:
- I took my local Porsche dealership for about a week where they tried to figure out what was going on. They compared the scans from my battery to another Macan EV loaner car…they concluded that both cars showed the hourly voltage spike, although with my car, the voltage spike was 3-4X larger than on the loaner car….and consequently, the voltage degradation on the loaner car was significantly less than what they observed on my car. They had no solution?

Anybody here experience anything like this?

Thx

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[craz8]

I now have a BTR-3 monitor winging it's way to me to do the same.

Once I have some data, I will try attaching my CTEK battery maintainer to see if keeping the 12v charged is what's causing my 1% daily drain.

 

[MacanEVOwner]

I now have a BTR-3 monitor winging it's way to me to do the same.

Once I have some data, I will try attaching my CTEK battery maintainer to see if keeping the 12v charged is what's causing my 1% daily drain.

Thx.

The CTEK will keep the voltage level at about 13.5v, but the hourly spike will remain. It’s something associated with how Porsche checks the other systems in the car….at least that’s what the tech support at my dealership said. But without the trickle charger attached, the voltage level will steadily drop.

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