Random flat battery

4.2 V8 32v FSI - 444 bhp
Post Reply
Rs4nutter
1st Gear
Posts: 88
Joined: Thu Jun 17, 2021 7:43 pm

Random flat battery

Post by Rs4nutter » Sat May 07, 2022 10:47 am

Hi all

Got back to car Friday afternoon to go home, and car wouldn’t start. Dials did their thing, but nothing!! Battery is less than a year old, but had noticed, not sure if related, keyless entry isn’t as good as it used to be. Keys both have new batteries in.
A friend had mentioned why I don’t put key into slot ever now and again, didn’t think it needs to as keyless!!
Any ideas would be good

P.s. want is adaptive headlight fault?? This comes up but not all the time

Thanks all

morski
3rd Gear
Posts: 369
Joined: Thu May 29, 2014 1:46 pm

Re: Random flat battery

Post by morski » Wed May 11, 2022 2:58 pm

Get a battery test done first to confirm the battery is still ok. Get the charging checked to make sure the battery is being supplied the correct voltage from the alternator, then look at current drain test to see which modules are still awake after locking and what the current draw is. Max should be 50mA, anymore and it will kill your battery in days
RS6 Performance Ascari Blue, Carbon Ceramics & Lots more..
A6 BiTdi Avant
Retrofitted: Full Led Headlights, DAB, Full Electric Seats, Power Tailgate, Surround View Cameras, Genuine RS6 Grille, Leather Door Armrests, Soft Close Doors, Rear Side Blinds, Electric Steering Column, LED Sill Plates, Ambient Lighting Pack, High Beam Assist, Eibach Springs, Led Roof Console, 4 Zone Climate, Rear Heated Seats, Head Up Display, Side assist, Alcantara Retrim

Rs4nutter
1st Gear
Posts: 88
Joined: Thu Jun 17, 2021 7:43 pm

Re: Random flat battery

Post by Rs4nutter » Wed May 11, 2022 7:31 pm

@morski have only done a voltage check with engine off and idling, 12.26v and 14.65v. Gonna get it booked in soon to have it looked over and ask them to check everything over
Thanks

morski
3rd Gear
Posts: 369
Joined: Thu May 29, 2014 1:46 pm

Re: Random flat battery

Post by morski » Wed May 11, 2022 7:37 pm

Those voltages seem fine. If you have a multimeter you can do a current draw check yourself. The parasitic drain test is where its time consuming and tedious
RS6 Performance Ascari Blue, Carbon Ceramics & Lots more..
A6 BiTdi Avant
Retrofitted: Full Led Headlights, DAB, Full Electric Seats, Power Tailgate, Surround View Cameras, Genuine RS6 Grille, Leather Door Armrests, Soft Close Doors, Rear Side Blinds, Electric Steering Column, LED Sill Plates, Ambient Lighting Pack, High Beam Assist, Eibach Springs, Led Roof Console, 4 Zone Climate, Rear Heated Seats, Head Up Display, Side assist, Alcantara Retrim

johnnydog
3rd Gear
Posts: 481
Joined: Sat Jun 11, 2011 8:24 pm

Re: Random flat battery

Post by johnnydog » Fri May 13, 2022 4:22 pm

Rs4nutter wrote:
Sat May 07, 2022 10:47 am
Hi all,

P.s. want is adaptive headlight fault?? This comes up but not all the time

Thanks all
When the battery is down on voltage, it throws up all sorts of random dash warnings/ faults, many of which are fictitious, and the system is fine when the battery is charged fully, or replaced.
When my battery was dying, I got a suspension fault warning. Apparantly, if the car detects a low battery voltage, then it shuts down certain systems until normal battery voltage is restored, hence the random dash warning lights.
Some have dismissed this point as unnecessary, but the correct type of AGM battey should be fitted on replacement, AND it should be coded to the car from the outset, otherwise certain electrical don't work quite as they should. I can't give specifics about this, or the specific issues it can cause, but I'm just quoting the Audi technician (who is very experienced and I've had dealing with for years - before any criticism is levelled at Audi servicing etc) who replaced my battery under the manufacturers warranty a few years ago, so my memory on the reasons he gave has faded somewhat since....

Rs4nutter
1st Gear
Posts: 88
Joined: Thu Jun 17, 2021 7:43 pm

Re: Random flat battery

Post by Rs4nutter » Sat May 14, 2022 6:50 am

@johnnydog cheers, have a friend at work with VCDS, Vagcom whatever it’s called, and he’s gonna plug it in and see what’s going on. If not him, will seek a specialist and let them look

boncrs
Neutral
Posts: 4
Joined: Sun Aug 18, 2013 1:48 pm

Re: Random flat battery

Post by boncrs » Sat Jun 04, 2022 9:36 am

Was this resolved? What was the fault?

Rs4nutter
1st Gear
Posts: 88
Joined: Thu Jun 17, 2021 7:43 pm

Re: Random flat battery

Post by Rs4nutter » Sun Jun 05, 2022 10:10 pm

Not yet, but probable cause may have been my dash cam not turning itself off!! However it’s currently sat in a garage to have some faults looked at and hopefully fix 🤞will let you know what the outcome is

Rs4nutter
1st Gear
Posts: 88
Joined: Thu Jun 17, 2021 7:43 pm

Re: Random flat battery

Post by Rs4nutter » Wed Jun 08, 2022 7:58 pm

Got call from garage today, all fine. Headlight fault was a knackered sensor which needed replacing

Post Reply

Return to “RS4 (B8 Typ 8K) 2012-2016”

Who is online

Users browsing this forum: No registered users and 104 guests