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2019 Audi e-tron Launch Edition 55
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Discussion Starter · #1 ·
I’ve noticed recently that using the comfort auxiliary heating function on the myAudi MMI app (whilst plugged in to shore power) is actually depleting the battery slightly.

This is how I can reproduce the problem:

1. Set car to 80% charge limit and plug in.
2. Leave overnight and check charge level in morning, myAudi MMI app reports 80% charge (no longer charging)
3. Initiate immediate or timed climate control, using either ‘comfort auxiliary air conditioning’ toggled on or off
4. Allow the heating/cooling to commence and then check the battery level using the myAudi MMI app after a few minutes. It should display something like 78-79% battery charge and the green light will be flashing on the car

I had always understood that preconditioning the cabin/battery would use shore power in this case rather than depleting the battery itself. I thought that the issue might be because the air conditioning pump was three phase and therefore needed to run the inverter to generate electricity from the DC battery, but I thought that there was a bypass to run the heating/cooling from AC.

With sufficient time of course the cabin will be heated and the battery will recover to 80% but it’s enough to knock a couple of percent off at least if you’re leaving in a hurry.

Anyone else notice the same behaviour or perhaps I have a fault?

PS I have a PodPoint charger
 

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I’ve noticed recently that using the comfort auxiliary heating function on the myAudi MMI app (whilst plugged in to shore power) is actually depleting the battery slightly.

This is how I can reproduce the problem:

1. Set car to 80% charge limit and plug in.
2. Leave overnight and check charge level in morning, myAudi MMI app reports 80% charge (no longer charging)
3. Initiate immediate or timed climate control, using either ‘comfort auxiliary air conditioning’ toggled on or off
4. Allow the heating/cooling to commence and then check the battery level using the myAudi MMI app after a few minutes. It should display something like 78-79% battery charge and the green light will be flashing on the car

I had always understood that preconditioning the cabin/battery would use shore power in this case rather than depleting the battery itself. I thought that the issue might be because the air conditioning pump was three phase and therefore needed to run the inverter to generate electricity from the DC battery, but I thought that there was a bypass to run the heating/cooling from AC.

With sufficient time of course the cabin will be heated and the battery will recover to 80% but it’s enough to knock a couple of percent off at least if you’re leaving in a hurry.

Anyone else notice the same behaviour or perhaps I have a fault?

PS I have a PodPoint charger
No, I think you don't quite have the mess sorted out. The only way to get the car to "precondition" the cabin while sipping from the wall to replenish the battery is when the preconditioning is part of a Timer process you have set up via the MyAudi app. If you set up a timer and include the "Precondition" option, then about 15 minutes before the entered Departure time, the car will start to heat the cabin while replenishing the battery. All other cabin preconditioning options will NOT replenish the battery, even if the car is plugged in.

In the Audi, you have 3 "conditioning" systems: 1) resistive heaters; 2) AC for cooling and dehumidifying; and, 3) heat pump for heating. When the car is fully off and idle, the heat pump cannot function, as it extracts stray heat from the battery, electronics and drive train as its means of providing heat. For a fully off and idle car, there is no heat to extract. Therefore, in a fully off and idle car, the vehicle relies either on the resistive heaters or the AC. However, the car will not pull power from the wall, unless the conditioning is part of a Timer setup.

Audi is kind of vague about all this, but is it possible that, if on a Timer, the heat pump might be able to provide some help by extracting excess heat from the recently charged battery. Overall, though, In the case of the Timer, the heat/AC works by first pulling from the battery. When the battery drops about 1%, the car recharges to full SOC. This cycle continues. The replenishing might also provide some waste heat. Still, the roll of the heat pump in all this is speculative....only Audi knows!
 

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Discussion Starter · #3 · (Edited)
In the case of the Timer, the heat/AC works by first pulling from the battery. When the battery drops about 1%, the car recharges to full SOC. This cycle continues.
Thanks for giving it some thought! Your point above seems to describe exactly the behaviour which I’m seeing - actually in both cases (timed and immediate). The terminology is actually a bit confusing here because we seem to have different wording in the app. Please see the two relevant screens below in the UK 2019 version of the e-Tron 55.

Comfort auxiliary air conditioning = do I use the three phase air conditioning or heat pump to do the cooling/warming.

1917


Within either the timer or quick start choice the same ‘air condition fully by departure’ terminology is shown, with the Settings choice leading to the screen above:

1919


I think this is called preconditioning in your app?

I’m going to reread the technical training documentation where I swear there was a description of the air conditioning compressor running from 3 phase alternating current or 2 phase AC if plugged in to a charger. The behaviour of partially depleting the battery before recharging the lost energy appears to suggest that the car is leaching charge (to run the A/C pump on 3 phase) by sourcing power from the battery via the DC to 3 phase inverter.

It wouldn’t matter to me at all apart from the fact that the preconditioning is taking a couple of percent at least and this means by the time the 15 minutes is up I’m ready to drive but don’t have as much power as when I started (7.2kW charge only at my home).
 

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Discussion Starter · #4 ·
I think it’s by design, but unfortunately not clearly defined as the exact reason.
1920
 

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Discussion Starter · #6 ·
Indeed. Perhaps it should say using the auxiliary climate control whilst plugged in will reduce initial charge until charge limit is reached again. This may not occur before departure time for preconditioning of the cabin is achieved.
 

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Indeed. Perhaps it should say using the auxiliary climate control whilst plugged in will reduce initial charge until charge limit is reached again. This may not occur before departure time for preconditioning of the cabin is achieved.
Well put. I vote for this phrasing as an addendum to the manual.
 

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I’m going to reread the technical training documentation where I swear there was a description of the air conditioning compressor running from 3 phase alternating current or 2 phase AC if plugged in to a charger.
What do you mean when you say 2 phase AC?
 
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