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Thread: B7 RS4 Flat Battery and Key Fob

  1. #1

    Default B7 RS4 Flat Battery and Key Fob

    Hey legends

    So I've had a long running issue with the RS4 where if I havent driven the car for a few days its really lazy on the start (hold button, wait, wait, then it turns over).

    So the other day I accidently left the key in the ignition and this completely drained the battery so it wouldn't even turn over.

    Got me thinking, is this drain issue something to do with the proximity key in some way? I have no idea how but throwing it out there to the more learned folk around here
    Current: 2006 B7 RS4 Avant in Imola

    Previous: 2004 A4 1.8 Turbo Quattro

    APR Stage 1 | Bilstein PSS9 Coilovers | Remus Exhausts | 18" RS6 Reps | Brushed Alum Mirrors | Phatbox | RS4 Pedals | RS4 Gear Knob

  2. #2
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    FWIW the B7 RS4 doesn't have a proximity key.

  3. #3
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    My RS6 experience which has similarities. If the car is left sitting the battery did drain in a few weeks. In my case it was primarily the alarm battery was faulty once disconnected it lessened the parasitic load. If the car alarm monitoring system isn't on, the load is further decreased. I use a CTEK battery sense and check the voltage via my mobile. If I'm not using it for a few weeks then it is on a charger. If your battery is old then thats you had, it just doesn't have the reserves to keep adecent charge with the inbuilt loads in the car.

    The CTEK actually plots battery % and it is very enlightening to look at the graph when you just open the door or boot. Quite impressive. Goes a long way to explaining the electrical complexity of these csrs.
    C5 RS6: Sportec, Milltek & Wagner -- B5 RS4 : tastefully modified -- Audi 1.8 quattro 132 Kw -- UNIMOG 404 TLF8

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    Quote Originally Posted by IchBautAuto View Post
    My RS6 experience which has similarities. If the car is left sitting the battery did drain in a few weeks. In my case it was primarily the alarm battery was faulty once disconnected it lessened the parasitic load. If the car alarm monitoring system isn't on, the load is further decreased. I use a CTEK battery sense and check the voltage via my mobile. If I'm not using it for a few weeks then it is on a charger. If your battery is old then thats you had, it just doesn't have the reserves to keep adecent charge with the inbuilt loads in the car.

    The CTEK actually plots battery % and it is very enlightening to look at the graph when you just open the door or boot. Quite impressive. Goes a long way to explaining the electrical complexity of these csrs.
    Sounds like good tech IchBautAuto. Might need to get myself one of these CTEK chargers.

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    Quote Originally Posted by oxblood8 View Post
    Hey legends

    So I've had a long running issue with the RS4 where if I havent driven the car for a few days its really lazy on the start (hold button, wait, wait, then it turns over).

    So the other day I accidently left the key in the ignition and this completely drained the battery so it wouldn't even turn over.

    Got me thinking, is this drain issue something to do with the proximity key in some way? I have no idea how but throwing it out there to the more learned folk around here
    Another vote for CTEK.
    I have used their equipment for years and if either of our cars is sitting idle for a few days I pop on a CTEK charger and let it do its thing.
    Just changed my first battery on the VW after six years.
    The wealth of tech on modern cars can cane batteries particularly on cars with auto start stop but not quite modern enough to have LED headlights - viz headlight 'coming home feature' the CTEK really helps mitigating the impacts.

    Dingah.
    Dingah

    2015 SQ5 TDI Sold
    2017 RSQ3 Performance Sold
    2018 S4
    Mrs B's Tiguan R-Line + APR

  6. #6
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    Quote Originally Posted by oxblood8 View Post
    Hey legends

    So I've had a long running issue with the RS4 where if I havent driven the car for a few days its really lazy on the start (hold button, wait, wait, then it turns over).

    So the other day I accidently left the key in the ignition and this completely drained the battery so it wouldn't even turn over.

    Got me thinking, is this drain issue something to do with the proximity key in some way? I have no idea how but throwing it out there to the more learned folk around here
    Have you ever replaced the battery in the RS? Could be the original Varta battery meeting it's demise. I know of a couple RS4 owners that are still running the original from factory! They were very solid batteries.

    Agree with the trickle charger comments, I'm going to look into getting one myself.

  7. #7

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    Quote Originally Posted by RS-Rated View Post
    Have you ever replaced the battery in the RS? Could be the original Varta battery meeting it's demise. I know of a couple RS4 owners that are still running the original from factory! They were very solid batteries.

    Agree with the trickle charger comments, I'm going to look into getting one myself.
    Yeah replaced the battery a couple of years ago. I do have a trickle charger so could use that but its just a PITA to hook it up all the time.

    In the grand scheme of things, its not really a huge issue as I drive the car most days anyways.
    Current: 2006 B7 RS4 Avant in Imola

    Previous: 2004 A4 1.8 Turbo Quattro

    APR Stage 1 | Bilstein PSS9 Coilovers | Remus Exhausts | 18" RS6 Reps | Brushed Alum Mirrors | Phatbox | RS4 Pedals | RS4 Gear Knob

  8. #8

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    Quote Originally Posted by IchBautAuto View Post
    I use a CTEK battery sense ....
    Any recommendations mate on which CTEK to get?
    Current: 2006 B7 RS4 Avant in Imola

    Previous: 2004 A4 1.8 Turbo Quattro

    APR Stage 1 | Bilstein PSS9 Coilovers | Remus Exhausts | 18" RS6 Reps | Brushed Alum Mirrors | Phatbox | RS4 Pedals | RS4 Gear Knob

  9. #9
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    Another thumbs up for CTEK chargers.
    Audi sell the CTEK MXS-5.0 charger as an OEM part (420093050E), you could start from there.
    I personally have a MSX-7.0 which I got from REPCO using NRMA discount, which was for the same price.
    Big car - FY Q5 TDI quattro sport with Technik package, Parking assistance package, Panoramic sunroof, Privacy glass and warm seats.
    Little car - T-Roc 4motion R Line with everything.

  10. #10
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    OK, a few elaborations. The battery sense is a bluetooth fitting left on the battey and connects to your mobile.
    battery sense.jpg

    An extension lead can also be fitted to the battery which is super helpful to connect the charger if the battery is in the boot.
    CTEK-CONNECTOR-TO-6-4MM-EYE-TERMINALS-18807.jpg


    I use a 10 amp charger. The biggest battery I have is 110 AH. A smaller charger wouldn't work adequately if it was flat.

    battery voltage.jpg

    extinguisher.jpg
    You can see the battery charger plugged in and also the graph on the phone.
    C5 RS6: Sportec, Milltek & Wagner -- B5 RS4 : tastefully modified -- Audi 1.8 quattro 132 Kw -- UNIMOG 404 TLF8

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