Data Logging the 12v Battery

[Philip_1]

Here is what AI is saying:

Yes — on the Macan EV, the 12-volt battery is charged from the high-voltage (main) battery, but only under certain conditions.

Here’s how it works in practice:

How the 12V battery is charged

The Macan EV uses a DC-DC converter to step power down from the high-voltage battery to maintain the 12V system.

When the car is “awake” (driving, charging, preconditioning, remote access, updates, etc.), the DC-DC converter actively charges the 12V battery.

When parked and locked, the car goes into a low-power sleep state.

While idle for a long time

During long parking periods, the car periodically wakes itself to:

Check vehicle status

Support security/telematics

Top up the 12V battery if its voltage drops

As long as:

The high-voltage battery has sufficient charge, and

There are no faults or abnormal parasitic drains
the 12V battery should stay healthy without needing a charger.

Important caveats

If the high-voltage battery is very low, the car may stop maintaining the 12V battery.

Extended storage (weeks/months), frequent short wake cycles, or aftermarket accessories can still drain the 12V battery.

Porsche (like most EV manufacturers) still recommends:

Keeping the HV battery above ~20–30% during long parking

Using a 12V maintainer only for very long-term storage (especially in cold weather)

Bottom line

Yes, the Macan EV normally keeps its 12V battery charged from the main battery, even when parked
But for very long idle periods or low HV state of charge, external support may still be advisable

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[sor]

I’ve got an update to share when I get more time. In short I had no problem running it down over three days with a 7W load, no reaction. I went down to 11.7v, confirmed with a separate volt meter, and had no problem unlocking and starting the car. It may have done something (or been worse) if I continued but this seemed like a reasonable point to stop the experiment.

I don’t consider this an issue since it’s a contrived situation, installing an accessory that drains the battery regardless of vehicle active or not. It’s just interesting to see how it would react. Probably not good for its lifespan to have an accessory drawing down the 12v battery regularly anyway.

One thing I will say is if you’re worried about the 12v for some reason, you can set a daily departure timer with cabin conditioning and it will wake up and charge it

 

[sor]

Here’s the data log.

Unlocking the car caused a noticeable dip in voltage, but otherwise did not trigger it to charge. Awhile later I set a departure time through the app and that successfully forced it to wake up and charge as you can see. I didn’t actually drive the car until hours later.

 

[hanashra]

Hello all, is there any update to this? If I am not mistaken, the latest software update was supposed to address the issue of the 12V battery draining whilst the car isnt in use for a prolonged period.

 

[sor]

Hello all, is there any update to this? If I am not mistaken, the latest software update was supposed to address the issue of the 12V battery draining whilst the car isnt in use for a prolonged period.

Nothing new to report. Just to be clear, the drain in this test was artificially added, it wasn’t meant to show if the car has issues with long term storage and 12v, I have no idea if that’s a problem or not. Instead I was attempting to see how it would react if an accessory was abnormally pulling a lot of power while the vehicle is switched off - if the car would kick in and charge during short idle periods to account for heavy accessory draw.

Without the artificial accessory drain, it could be that the battery would last many months to a year, or there may be a longer term timer that kicks in and tops it off. This wasn’t investigated my me as I have no reason to let the car sit that long.

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