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Major battery drain

Discussion in 'VCDS (formerly VAG-COM) forum' started by LeeT, Mar 15, 2013.

  1. LeeT
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    LeeT Member

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    [Mar 15, 2013]
    I could do with some help here. My car is an Audi A5 3.0 tdi. Car was fine one day but came out in the morning and it was completely dead, not even a dim dash light. I assumed knackered battery so bought a new one. All was fine for the two hours i drove it and then parked it up. Next morning, same thing completely dead. I put my multimeter on battery and it had drained to 5.5v. As the car is under warranty (warranty wise :( ) I took it to a non Audi garage. Ive just rang them and they say that there are no fault codes logged and it hasnt lost any charge allday and cant find anything wrong with it. As they cant find a problem im going to get hit with a ridiculous bill :(
    Anyway, i have a friend coming around tomorrow with a genuine vcds cable. Where should we start looking? How could there be no fault codes registered? Surely there would be loads considering ive had to put jump leads on the under bonnet terminals just to get the handbrake released and boot open?

    NHN, Sent you a PM regarding a cable
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  3. lgooch
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    lgooch Active Member

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    [Mar 15, 2013]
    Park the car up with the bonnet open. Leave it for an hour

    You will need a multimeter and take a reading on the number of amps it's consuming. It should be close to zero. It will draw some but not a lot normally.

    If amps are high start pulling fuses out one by one and see which one causes the draw on the battery to drop. Look in the manual and see what the fuse powers and this should give you an idea where the fault lies.

    Plenty of videos on you tube to show you how
    #2
  4. LeeT
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    LeeT Member

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    [Mar 15, 2013]
    Thanks for the reply. I would like to think the garage has taken this approach already. Would there be anything i could check with vagcom?
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  5. lgooch
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    lgooch Active Member

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    [Mar 15, 2013]
    I would double check if the garage has

    All vagcom will do is indicate a fault with a sensor as such. It could be something as simple as a boot light which is not going out which vagcom may not pick up on.

    I would go back to basics if vagcom pulls up nothing
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  6. LeeT
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    LeeT Member

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    [Mar 15, 2013]
    Happy to take all advice so will definitely give this a go. I would have thought it would be something a bit more substantial than a boot light to run down a 3.0tdi battery to 5v overnight? I have told the garage to keep it tonight, apply the electronic handbrake and arm the alarm as i would at home and see what happens. Thing is, warranty only covers electrical components, not wiring so i need to be careful that i don't end up being wallet raped
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  7. lgooch
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    lgooch Active Member

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    [Mar 15, 2013]
    It could be something like a dodgy radio which isn't powering off. Hope you get it sorted
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