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Thread: B7 RS4 lazy start issue

  1. #1

    Default B7 RS4 lazy start issue

    Hi All

    Have had this issue for a number of years now where after leaving the car for a few days the start can be quite lazy. Push the start button, then nothing for say 5 to 10 seconds then it fires up.

    However today, I could not get it started. Press the start button and I could hear a few audible clicks. Nothing.

    Checked the battery and it was sitting at 11.7V. So I hooked up my portable battery charger. Turned over the key and it instantly fired up.

    So I got the battery replaced in 2019 and at the time we looked in the Delkor catalogue and selected the battery that suited the car. However, this battery was physically smaller than the previous OEM Varta battery.

    I had a look again today on the Delkor website and it quoted a different battery to suit the car, and one that physically would be the same size as the OEM. Here are the specs on what should be fitted to the car



    Here is the battery in it at the moment.



    To me, it's clearly the wrong battery.

    So a few things here.

    1. Do I replace the battery as a first port of call?
    2. I've read that the symptoms I am experiencing are due to a problem with the starter motor. Should I replace that?
    3. Maybe I have some kind of parasitic drain going on here and an Autoelec should check it out.

    Thoughts?
    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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    If you know the battery to be undersized/under spec I would start there.

  3. #3
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    If it is anything like my cars, the more exotic the spec, the quicker the battery drains. My A4 will sit for months without dropping below 60% whereas the RS4 is less and the RS6 less again. I have a cetek battery monitor on every car and you can log the drop in volts if you just open the door. The alarm and convenience modules are current users so the more you have, the more you use, 24/7 even when you sleep. Irrespective of use I have my cars on a charge every 2 weeks. There is nothing wrong with your starter motor if it kicks over with a fresh battery. 11.76 volts is a dead battery to all purpose. Get a new one, best you can afford and maintain it like your life depends on it. Just grab a glass, sit and think of the systems in your car and it will quickly become obvious why there is no correlation between your car and the same battery in a 1960-70's car where it is tootally isolated from any current draw (if you remembered to turn the lights off)
    C5 RS6: Sportec, Milltek & Wagner -- B5 RS4 : modified -- B5 Audi 1.8 quattro 132 Kw -- 2007 VW Touareg TDI 3.0 with air suspension and lockers-- UNIMOG 404 TLF8

  4. #4
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    When the battery died in my RS4 I opted to go like for like and bought a Varta. A fully charged SLA, sealed lead acid, battery cell voltage is 2.2 volts per cell, so a fully charged battery will be 13.2 volts. The other thing you need to consider is the CCA, cold cranking amps, capacity. If you are buying an alternate, CCA capacity needs consideration.

    If you have a charger with a reconditioning function charge the battery with that function, that can revive slightly sick batteries. I run Ctek chargers on my cars but this will not stop a battery from failing. My RS4 battery dropped a cell while on the charger, the charger then goes into current limit still trying to charge the battery.

    Get a load test done on your existing battery, that will give you some idea of battery health. Parasitic drain is not hard to check just time consuming, a DC tong, clamp tester is the best tool to use.
    Current - 2007 B7 RS4 Avant, APR Stage 3, Milltek with Hi Flo Cats, GruppeM intake, Sachs Clutch, Factory Ceramics, JHM Shifter, RS6 FBSTW, AMI & Hi Res RSNE
    Current - 2012 B8 A4, 2.0T Quattro Avant SLine
    Current - 2001 B5 S4 Imola Yellow Avant
    Current - 1989 B3 90 Quattro - 7A NA Engine, (Long Term Restoration Project)
    Current - 1984 WR Ur Quattro

  5. #5
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    Iíve had issues with battery In the past from an old tracker that had a backup battery that was killing my main car battery.

    Once I pulled the old tracker back up battery out that solved an issue with my new battery not having enough charge to start car after 1 week.

    I also thought that I had an issue with starter motor as well but that wasnít the case.

    I would start with the cheapest option and that is put a ctek on it when your not using the car. I bought the MXS 10.0 and that can completely recharge battery over night if it is flat.

    Yes, you could put a bigger battery in with higher CCA but I think a ctek on it could help a lot.

    I do believe there is a parasitic draw with my car but between the aftermarket head unit, amplifiers and the S/C coolant pump that runs on for 20 min every time I stop the car it is easier for me to charge and top up the battery every couple of months.

    I also carry a Noco jump pack in the boot all the time just in case I need it.


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  6. #6

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    Thanks for the replies everyone

    Mike, with the ctek, you just hook it up and leave on charge whenever you are not using the car? You just hook this up on the terminals under the bonnet?

    I see Repco has the MXS 10.0 on sale at the moment so might grab one.

    Sent from my SM-N975F using Tapatalk
    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

  7. #7
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    Quote Originally Posted by oxblood8 View Post
    I see Repco has the MXS 10.0 on sale at the moment so might grab one.
    Agreed that a quality battery charger such as the CTEK MXS 10.0 is an essential item to have in the garage, particularly with the more modern cars where the demands placed on the battery are greater than ever. Well worth the spend and you will not regret it.

  8. #8
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    Iíve got the pigtails that come with ctek hardwired to the battery in the boot all the time and use that when itís easy access. I.e boot isnít full of crap.

    Otherwise under the bonnet with the alligator clips onto the battery post under bonnet works fine as well. You can sit ctek on LHS rocker cover and still close bonnet fully without any issues so you can still lock car and leave on charge if required.


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  9. #9
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    An alternative is to use the Ctek fitting that is installed in the trim. Just pop the boot and plug in the MXS 10. I have a couple of these fittings for the RS6 and Touareg where the batteries are not easily accessible. Plus a few chargers. I put mine on every two weeks. I have left the Ctek on for a few weeks but I am not totally confident in the software once it goes into maintenance mode after about a week so prefer not to use it like that.
    extinguisher (2).jpg
    C5 RS6: Sportec, Milltek & Wagner -- B5 RS4 : modified -- B5 Audi 1.8 quattro 132 Kw -- 2007 VW Touareg TDI 3.0 with air suspension and lockers-- UNIMOG 404 TLF8

  10. #10
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    I've just got mine sticking out of the boot bottom (internal) and plug the connector in to that..

    The problem is that I've driven away with the charger still connected twice now... So much so that last time it striped the connector. I've had to put on some electrical 'connectors'. AND, I've driven away with it connected again, but this time is just pulled apart the connectors, job done!

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