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Thread: Flat Battery

  1. #1
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    Flat Battery

    Has anyone come across a flat battery on a new’ish car, two year old?

    I recently noticed that my brake lights come on once I’ve locked the car up. I later on found out that it was to do with a faulty brake light switch, which I haven’t replaced yet. I managed to jump start and drive the car around to charge the battery up. Then after about a day or so the battery goes flat again. I’ve made sure that none of the lights are on before I lock up, I can’t figure out what going on.

    Any ideas would be great!

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    Re: Flat Battery

    My next door neighbours car had a mystery battery flattening problem, turned out that it was the switch keeping the glove box light on. Replaced it and all is now well. Quite how he found it I dont know. How do you know the light is on all the time in your fridge for instance...

    Happy hunting

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    Re: Flat Battery

    "How do you know the light is on all the time in your fridge for instance..."
    You drill a hole in the door....

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    Re: Flat Battery

    Not very stylish, I took all the stuff out of mine and sat inside....the hole in the door is great for spying on folk in the kitchen though...

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    Re: Flat Battery

    [ QUOTE ]
    Rakesh said:
    Has anyone come across a flat battery on a new’ish car, two year old?

    I recently noticed that my brake lights come on once I’ve locked the car up. I later on found out that it was to do with a faulty brake light switch, which I haven’t replaced yet. I managed to jump start and drive the car around to charge the battery up. Then after about a day or so the battery goes flat again. I’ve made sure that none of the lights are on before I lock up, I can’t figure out what going on.

    Any ideas would be great!


    [/ QUOTE ]

    Have you added anything to the car lately i.e. change in stereo or similar?

    If not then sit inside the car at night and lock it to see if any of the interior lights are still on, and also listen to see if you can still here anything powered.....try not to drill too many holes if possible as they can reduce the resale value [img]/ubbthreads/images/graemlins/grin.gif[/img]

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    Re: Flat Battery

    cant you put a multi meter across the battery to and see if there is an abnormal current across it? Cant rightly rememeber how exacly you check the current, parallel or serial etc [img]/ubbthreads/images/graemlins/lol.gif[/img] Gambba's an engineer - he will know [img]/ubbthreads/images/graemlins/wink.gif[/img]

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    Re: Flat Battery

    [ QUOTE ]
    Gambba said:
    [ QUOTE ]
    Rakesh said:
    Has anyone come across a flat battery on a new’ish car, two year old?

    I recently noticed that my brake lights come on once I’ve locked the car up. I later on found out that it was to do with a faulty brake light switch, which I haven’t replaced yet. I managed to jump start and drive the car around to charge the battery up. Then after about a day or so the battery goes flat again. I’ve made sure that none of the lights are on before I lock up, I can’t figure out what going on.

    Any ideas would be great!


    [/ QUOTE ]

    Have you added anything to the car lately i.e. change in stereo or similar?

    If not then sit inside the car at night and lock it to see if any of the interior lights are still on, and also listen to see if you can still here anything powered.....try not to drill too many holes if possible as they can reduce the resale value [img]/ubbthreads/images/graemlins/grin.gif[/img]


    [/ QUOTE ]

    I did add a bass box, but is has been taken out. No wires etc were cut or anything, made connections using the block connector for the bose bass box.

  9. #8
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    Re: Flat Battery

    I’m going to jump start the car tonight and I’ll sit inside it to see if there are any lights or abnormal noises, but I’m not planning on drilling any holes! I’ll put a meter across the battery and see what happens.

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    Re: Flat Battery

    Might be that the battery has gotten so flat over time that it has damaged a cell in this casse it's a new battery I'm afraid.

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    Re: Flat Battery

    [ QUOTE ]
    RS4 Barry said:
    Might be that the battery has gotten so flat over time that it has damaged a cell in this casse it's a new battery I'm afraid.

    [/ QUOTE ]

    Yeah this should be the one of the first things to check, but normally you'll only find this by checking the SG's (Specific gravities) of the individual cells.

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    Re: Flat Battery

    [ QUOTE ]
    khufu said:
    cant you put a multi meter across the battery to and see if there is an abnormal current across it? Cant rightly rememeber how exacly you check the current, parallel or serial etc [img]/ubbthreads/images/graemlins/lol.gif[/img] Gambba's an engineer - he will know [img]/ubbthreads/images/graemlins/wink.gif[/img]

    [/ QUOTE ]

    He should, doesn't mean he does! but the good thing is he can [censored] his way out of it!! [img]/ubbthreads/images/graemlins/goofy.gif[/img]

    It would need to be mounted in series in order to determine the current draw through the circuit, but this is a bit advanced along with checking the battery at this stage.

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    Re: Flat Battery

    [ QUOTE ]
    Rickquattro said:
    My next door neighbours car had a mystery battery flattening problem, turned out that it was the switch keeping the glove box light on. Replaced it and all is now well. Quite how he found it I dont know. How do you know the light is on all the time in your fridge for instance...

    Happy hunting

    [/ QUOTE ]

    First of all make sure everything is switched off and disconnect the negative lead from your battery. Then touch the negative lead to the terminal again on the battery and if you get a spark it shows that there is current passing through (ie something is on and slowly draining the battery). The glove box light as mentioned could be the cause as could the boot light. If you do get a spark you'll have to hunt down the cause, for example remove the boot light bulb and see if you get a spark again, if not hey presto thats the culprit.

  14. #13
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    Re: Flat Battery

    I don't think that is a sure way of testing for current draw as the radio, clock, central locking ect will be live all the time plus anything connected with a capacitor in it will draw more when it is first connected to the battery.

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    Re: Flat Battery

    Back to the advice for my mates A2, a suggestion was put a multimeter between the earth lead and the battery terminal, noting the current drain. Start pulling fuses and note any change in the multimeter. Ones to go for first are interior lights etc....god luck. I find electrical niggles the worst to track down..

  16. #15
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    Re: Flat Battery

    Well I jump started and drove around, parked up and no lights etc were on. The only lights that were on are the alarm led lights flashing. The glove box light only comes on if dip head lights are on. There is a slight power consumption, most likely to do with alarm and the on board computer.

    [ QUOTE ]
    RS4 Barry said:
    Might be that the battery has gotten so flat over time that it has damaged a cell in this case it's a new battery I'm afraid.

    [/ QUOTE ]

    RS4 Barry, your probably most likely corrected. I think my bass box and amp must have used a lot of power and in time, slowly drained the battery out. My car is still under warranty, so I’ll book it in and let the Audi engineers check it out. If it is a dieing battery, all I can do is purchase another one.

    Thanks for your help.

    Happy Xmas & A New Years.

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    Re: Flat Battery

    [ QUOTE ]
    neil.c said:
    I don't think that is a sure way of testing for current draw as the radio, clock, central locking ect will be live all the time plus anything connected with a capacitor in it will draw more when it is first connected to the battery.


    [/ QUOTE ]

    Yes the radio when switched off and the clock etc are live, however they are only drawing off a very small amount of charge from the battery which shouldn't be strong enough to produce a spark. If an interior light or the radio for example is left switched on this produce a visible spark which you will also hear too. You can use a multimeter if you wish however you should not have a spark when connecting the battery if everything is switched off, if you do then something is drawing off sufficient charge to discharge the battery over a short period of time.

  18. #17
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    Re: Flat Battery

    Rakesh - is that an S3 you have? Nice colour mate! Same thing happened to me a while ago - My battery ran flat from my ICE system, then I upgraded to an S3 battery and no problems since!! [img]/ubbthreads/images/graemlins/grin.gif[/img]

  19. #18
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    Re: Flat Battery

    Yep, that's a real S3! Colour is Ming Blue with pearl effect.

 

 

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