Hi Audi enthusiasts.
Got an issue with battery charging on my 2015 Q7 TDI. If car is not driven for a day - battery dies completely, can't start the car, have to use jump start. Replaced the battery. Same problem. Battery voltage, while parked drops, it could be 12.4 when I leave at night and 11.8 in the morning.
Now got a new issue, B&O amp produces no base, nothing coming from door bass speakers or the sub. Replaced the amp and got the same result.
Here is the scan for the sound:

Address 47: Sound System Labels: None
Control Module Part Number: 4L0 035 466 A HW: 4L0 035 466 A
Component and/or Version: BO Q7 H30 0110
Software Coding: 0D000001
Work Shop Code: WSC 31414 790 00001
VCID: 295948A340F92BDEB4-807C
5 Faults Found:

03000 - Amplifier for Digital Sound Package (R184)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 5
Fault Frequency: 30
Reset counter: 25
Mileage: 216998 km
Time Indication: 0
Date: 2025.01.16
Time: 14:18:13

Freeze Frame:
Voltage: 14.30 V
Temperature: 44.0°C
Bin. Bits: 00000100
Bin. Bits: 00000011
Bin. Bits: 00000000

00869 - Line Output; Rear Right
011 - Open Circuit - Intermittent
Freeze Frame:
Fault Status: 00101011
Fault Priority: 5
Fault Frequency: 1
Reset counter: 65
Mileage: 216998 km
Time Indication: 0
Date: 2025.01.16
Time: 14:18:33

Freeze Frame:
Voltage: 14.40 V
Temperature: 44.0°C
Bin. Bits: 00000100
Voltage: 12.70 V
Temperature: 72.0°C
Bin. Bits: 00000000
Bin. Bits: 00000000

03405 - Bass Loudspeaker
011 - Open Circuit - Intermittent
Freeze Frame:
Fault Status: 00101011
Fault Priority: 5
Fault Frequency: 1
Reset counter: 65
Time Indication: 0

Freeze Frame:
Voltage: 12.00 V
Temperature: 32.0°C
Bin. Bits: 00000011
Voltage: 12.20 V
Temperature: 72.0°C
Bin. Bits: 00000000
Bin. Bits: 00000000

03278 - Functionality Limited due to Missing Messages
000 - - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 6
Fault Frequency: 1
Reset counter: 65
Time Indication: 0

Freeze Frame:
Voltage: 13.90 V
Temperature: 33.0°C
Bin. Bits: 00000011
Voltage: 13.50 V
Temperature: 28.0°C
Bin. Bits: 01110010
Bin. Bits: 00000000

03017 - Motor for Left Front Treble Speaker (V344)
014 - Defective - Intermittent
Freeze Frame:
Fault Status: 00101110
Fault Priority: 5
Fault Frequency: 2
Reset counter: 65
Mileage: 217197 km
Time Indication: 0
Date: 2025.01.19
Time: 16:42:08

Freeze Frame:
Voltage: 13.80 V
Temperature: 32.0°C
Bin. Bits: 00000100
Voltage: 13.50 V
Temperature: 28.0°C
Bin. Bits: 00000000
Bin. Bits: 00000000

After the reset only errors I get are for the trunk motors:

Address 6D: Trunk Elect. Labels: 4L0-910-945.clb
Part No SW: 4L0 910 945 HW: 4L0 827 851 F
Component: ValeoHeckdeckel H58 0500
Revision: --H58001 Serial number: E5030000B
Shop #: WSC 98765 666 38354
VCID: 6CD771B74F8BFEF60F-8038

Subsystem 1 - Part No: 4L0 910 946
Component: ValeoHeckdeckel H58 0500

Subsystem 2 - Serial number: / ó

Subsystem 3 - Serial number: RD09.02.15--H58001002E0315ÿ

Subsystem 4 - Serial number: 2E0315ÿ

4 Faults Found:
03047 - Motor (in Trunk/Hatch control module) (V375)
012 - Electrical Fault in Circuit - Intermittent
Freeze Frame:
Fault Status: 00101100
Fault Priority: 3
Fault Frequency: 1
Reset counter: 47
Mileage: 216423 km
Time Indication: 0
Date: 2013.04.02
Time: 22:48:43

03048 - Motor (in Trunk/Hatch control module 2) (V376)
012 - Electrical Fault in Circuit - Intermittent
Freeze Frame:
Fault Status: 00101100
Fault Priority: 3
Fault Frequency: 1
Reset counter: 47
Mileage: 216423 km
Time Indication: 0
Date: 2013.04.02
Time: 22:48:43

01331 - Door Control Module; Driver Side (J386)
004 - No Signal/Communication - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 3
Fault Frequency: 1
Reset counter: 57
Mileage: 216793 km
Time Indication: 0
Date: 2025.01.14
Time: 16:29:18

00532 - Supply Voltage B+
002 - Lower Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 3
Fault Frequency: 2
Reset counter: 40
Mileage: 216423 km
Time Indication: 0
Date: 2013.04.02
Time: 19:32:52

Any help/suggestions? Not even sure where to start

 

You've got multiple fault codes telling you there's an electrical fault in circuit. If you look at the measured voltage values captured by many of the fault messages (there are two site measurements), the voltage value differs by a reasonable gap, indicating you also have the typical parasitic drains and grounding strap issues these Q7s get over time. A lot of owners also report that when they lock car/alarm activated, that's when their battery is dead in the morning, etc. If they don't activate the car's alarm system, then their battery is still ok the next morning.

So you probably need to do a bit more thinking/observation around what's the 'primary' cause of your voltage drop on the battery overnight. The alarm system, BTW, is located at the bottom of the plenum area below windshield, and below the brake master cylinder for reference purposes. This is also why it tends to get damaged from water incursion when the plenum drains get clogged and water backs up over that alarm module, etc.

If you've got access to a FLIR camera (heat sensing), that can help you locate battery drains very quickly, and if not, then VCDS does have a test sequence for voltage drains, but there's some prep work goes into setting up car for the test, etc. There's also a nifty test for the fiber optics Bus in VCDS, which pertains to the entertainment system, so that's an easy check you want to do first related to the sound system, but do keep in mind low voltage on this car usually results in wonky things happening, and this car can shut down myriad accessory items in response to low voltage sensed, so pay attention to all error/fault codes present...don't cherry-pick what you think is important, as everything is linked on this car.

Now that you got a fresh battery in car, keep it on trickle charger, and if got a voltmeter you can easily check for problems with your engine grounding straps, which is very common too, but often not visible to outward observation. You really just have to begin eliminating variables. On mine, if I lock it w/alarm from key fob, it affects the battery voltage. Not a problem if driven every day, but if it sits in place like that...it's downhill battery voltage.

 

Thank you. All good suggestions. Only one one thing to note, I do not lock the car EVER. Living in f..ing San Francisco my car(s) gor broken into 5 times in a time span of 1.5 years, so i stopped locking the car, hoping to save on windows replacement ... guess what, on the last break in - still got windows smashed , even though the car was unlocked.
Still looking for the root cause.

 

That one is just fairly common due to the water drains clogging/ backing up in the plenum beneath windshield, etc. The light sensor/ rain sensor located on the windshield can ground itself too. That one you can just check for heat by touch, as it tends to get fairly warm when failed. Again, a heat-sensing camera (FLIR) is used by car shops to locate these types of electrical drains quickly, and obviously if yours is going dead overnight, it's a fairly large drain.

As the car is providing you with fault codes noting there are electrical faults in circuit, I'd start there...pull those fuses, etc.

https://fuseandrelay.com/audi/q7.html