Audi A3 Sportback TFSI e 2021 (UK) 12v Battery Charging

[rozel]

Last week I went away over 5 nights and left my car standing. When I got home and switched it on to go somewhere I got a Total Electrical Failure message which included the yellow waring on the Virtual Cockpit and a Red Battery warning on MMI. Fortunately it started and after a return journey of around 8 miles it seems ok with no further warnings since. I am guessing though that the 12v battery is well depleted and myAudi struggles to connect to vehicle.

I'm going away for a much longer period (over 5 weeks) and again the car will be left standing. Done some research on the forums and can only find guidance for eTron models sold in the US. I'm appealing to members who have experience in charging their 12v batteries and would like to ask the following: -

1. Is the 12v Battery definately under the bonnet? I'll send a photo if needs be but I'm struggling to see the terminals as detailed in my manual - definately not in boot as far as I can tell. Some help here would be appreciated
2. I have what I think is a pretty standard battery charger will this suffice? I believe I must connect the Negative to the chassis - advice as to where would be welcome
3. I'd like to lock the car whilst charging - will the cables be able to exit the bonnet without being damaged when shut?
4. Any other advice/recommendations would be seriously useful - the weather isn't expected to be close to zero as it was last week but I don't want to take any chances.

Thanks in anticipation

 

[rozel]

BUMP

I'd be grateful if someone could help me please. This issue ocurred again today justifying that my 12v Battery is completely out which can, I understand, cause chemical reactions and kill the battery altogether! Today again I had the Yellow and Red warnings - interestingly today, the Battery Icon on the Virtual Cockpit alternated between red and yellow for a couple of miles, then maintained yellow until it disappeared altogether. And on my return leg, again of about 5 miles it remained off.

Can connect easily now to myAudi and have scheduled a charge of High Voltage Battery for the wee small hours and hopefully it will proceed ok.



In the meantime I'm attaching photos - I believe the 12v Battery is top left in first pic and second is a closeup but am unsure how to connect Charger's Leads, which are clamp style. Third pic is the box containing my Charger.

I don't really want to contact my Dealership and surely someone has gone through what I am going through

Thanks

 

[Vic20]

What was the charge level of the HV battery when you parked up?

As the vehicle doesn't have an alternator, the case with EVs and Hybrids is usually that the 12V battery is kept charged through the HV system. If the HV battery charge level is low or it detects an issue with the 12v battery, it wouldn't supply it to protect itself from harmful deep discharge.

I would try a simple plugging in of the vehicle first to see if the 12v battery recovers.

I'm pretty sure the 12v battery is not under the bonnet.

 

[rozel]

Thanks @Vic20 .

So are you saying that the battery shown in the above photos is not a battery then? Before I went away there were 20 miles appx in the High Voltage Battery available and this morning there were about 10 miles. In both instances the 12v battery recovered. In this cold weather I never get more than 28/29 miles capacity. I think you are being very general as my car's manual clearly states that my battery it is under the bonnet - I have checked under the boot floor and can't see anything at all unless it is under the light blue moulded plastic/resin cover. This is securely bolted down though and will be difficult to remove.

Not sure if you've read my second post though a few minutes before yours but as I mentioned in my BUMP post I have a charge of the main high voltage battery scheduled for the early hours of tomorrow morning.

 

[Vic20]

Looks like our posts crossed.

No, the unit you mention under the bonnet is the inverter unit, converts the 400v of the HV DC into 3 phase AC amongst other things like regen and definately NOT to be touched. Anything with orange cables is HV and stay away!

" I think you are being very general as my car's manual clearly states that my battery it is under the bonnet "
Found this https://www.audi.ch/content/dam/nem...-vehicles/PDF/pdf-getrennt/RDB_Audi_A3_EN.pdf Look at page 25, it shows the 12v is under the bolted cover in the boot next to the fuel tank. This is unique for the TFSIe model

By your description of events it either looks like the 12v battery is in a bad way or something is causing a large battery drain whilst parked up. I would seriously suggest to speak to the dealer and get this looked at under warranty.

 

[rozel]

Thank you @Vic20 your post is extremely helpful. I must presume my A3 Owners Manual is too general lol! Before even thinking of charging the 12v battery now, I'll see what tomorrow's HV charge brings to the table and then I'll ring my Dealership. Not sure though what could be draining te 12v battery when standing. That said I mainly do short journies then charge but I have read the battery does drain when standing.

I shall plug a warranty claim - thanks again for your help.

 

[rozel]

Ok so the charge overnight went well, no issues at all and it went in accordance with all the others so my phone said via myAudi I disconnected the charging cable and then immediately switched on my car via the Button (ie; car was ready to go out on a drive) - not a single warning light came up and it was extremely cold last night where I am on East Coast +2 degrees C. Only got 25 miles this time not good I know but what I get at these temperatures. But this must be good yes?

So given I was expecting a similar situation as per last couple of days, does this mean when undertaking a std PHEV Charge (High Voltage Battery) that it charges the 12v Battery too? I shall be ringing my Dealership later - having my morning's coffee right now - I'll update when I hear something meaningful.

In the meantime maybe @Vic20 could give me his thoughts again please?

 

[rozel]

Car booked into Dealership for next Thursday to have system fully checked over

 

[Vic20]

Hi Rozel

25 miles from a cold start with a cold gearbox is ok I'd say, the best I've managed in those sort of temperatures is 33 miles. Best ever in perfect conditions is 42

Yes, as is the case with all EVs, the 12v battery is smartly charged from the HV battery via a voltage converter but I'm pretty sure this is only when the vehicle is switched on or the vehicle is being charged from AC mains. The energy capacity of the HV battery compared to the 12v one is massive in comparison.

Is it possible when you left the vehicle for 5 days you left anything powered on like parking lights by knocking the indicator stalk? Obviously the 12v battery wasn't completely dead when you went back to it as you managed to 'start' the vehicle. The 8 mile journey might not have been enough time to replenish the 12v enough.

Hopefully, the full overnight charge has sorted the 12v but I'd certainly keep the dealer appointment and try to explain your experience to the Tech guy and not the Service agent.

Let us know how you get on

 

[rozel]

Yes I suppose 25 miles isn't too bad. Yesterday I went on several local runs in the car stopping and starting numerous times and not a single issue! The dealership (via a technician) said a couple of interesting things: - 1. That the HV Charging doesn't charge the 12v battery and so I must assume it gets its charge from the Alternator (assuming there is one?) - @Vic20 can you comment again please? 2. The same technician has come across this issue before and thinks there could be a software update to cure it. I cannot think what, if anything, was left on whilst I was away recently so my answer is no - the fact that I could start the car during the 2 days after getting back does suggest all this could be more of a technical fault. Wishful thinking on my part but one lives in hope

I charged the HV battery again last night, again no issues and miraculously I got 27 miles - temperatue went down to zero overnight.

May I comment though that I'm a little surprised no other member has had this problem or think to record their issues here.

 

[JKP]

The 12V battery shouldn't be draining in that short time, it's for sure. We may have longer -15-20 ºC temperature periods here and all cars including plug-in hybrids are supposed to start normally, even after standing several days. The software issue can maybe allow some function to stay on and drain the battery, as there's lots of complex coding behind the hybrid system so it might be a solution. If the software update doesn't fix the problem then there's surely something in the hardware. Could be simply a faulty battery, some of them seem to break up within a year.

 

[rozel]

Thanks @JKP much appreciated. Well hopefully the dealership will put my mind in order next Thursday. I'm worried as well that a replacement 12v battery is going to cost me - I'm in the 12 months Audi Warranty that the dealership gave me when I purchased the car last August as the 3-year from new one expired eo March this year. Not sure if this warranty covers me - again we will see next week.

 

[Vic20]

Rozel

No EVs / PHEVs have alternators. They have far more sophisticated electronics to save the weight of this unnecessary energy conversion unit in such vehicles.

When the vehicle is running and the HV battery is too low, 12v power from the voltage converter unit is derived from the electric motor/ regen unit.

Your dealership didn't speak to the correct technician!

 

[rozel]

@Vic20 You are of course quite right and this was the case when I did my previous post. The dealership didn't say anything about alternators, it was just me being too general again!

No I trust my dealership - been with then for many years now. Yestersay I travelled 45 miles to help my daughter move house and 45 miles back. Again numerous stops along the way and the car didn't put a foot wrong. Granny charged it up before I set back homewards and using my sat nav got well over 80mpg (both directions) driving on Intelligent Hybrid Mode, which I couldn't complain about given the undulating and very hilly journies, Granny charged it again overnight and this morning I've got 25 miles, which isn't too good. Temperatures due to rise this coming week, so hopefully I'll get a better figure.

May I ask if this thread is in the correct sub-forum for my car please? I put this and older threads in this one despite there being G-Tron forum because my car isn't a G-Tron model it is a "TFSI e" one.

 

[Vic20]

I guess it should really be in 'A3 Sportback e-tron' thread as it has more commanalities with that variant.

 

[rozel]

@Vic20 - Yes I meant e-tron lol!

 

[rozel]

@Vic20, @JKP and all - Car went in to Audi yesterday and they plugged in their diagnostic kit etc. They've found issues centred around the car's Charging Socket. Had a long discussion with the technician but he bamboozled me talking about the Socket's "Lock Pin". I confirmed that the plug is locked in when I lock the car using the remote. He reckons the pin connection isn't sending the proper signals to the car and he's convinced that it is this issue that causes the 12v Battery to deplete when standing. I don't understand tbh as the car charges perfectly (indeed got 32 miles last night ) and don't really know why the issue he's described can cause battery depletion. He also said with the car Charged and the Socket replaced, 6 weeks standing shouldn't be an issue but recommended fully charging the car at the start of the standing period.

However they're supposed to know more than me so the car is booked in for the replacement socket (under warranty) next Thursday and I can only keep my fingers crossed that this solves the issue. I would welcome any comments in the meantime - thanks