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Battery keeps draining - 1.9tdi

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by DodgeT, Feb 10, 2014.

  1. DodgeT
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    DodgeT Member

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    [Feb 10, 2014]
    A few weeks ago, would notice the hazard light on / off randomly when locked. Few days later, the car was absolutely dead after being stood for a couple of days. Jumped ok but then was flat the next morning. Put a new battery on, and all was ok for a week or so, now same thing again. If left for 24hrs, its dead.
    Done lots of googling only to determine nothing much other than the usual checking battery drain, pulling fuses till it stops etc, apart from the mentioning of the CCM.
    Is this a good place to start, ie replacing this module?
    #1
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  3. S4_dan
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    S4_dan Fire up the Quattro!

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    [Feb 10, 2014]
    The CCM can be pricey.

    I'd start with checking what drain you have from the battery. (high or low) Then you can look at what uses high current or low current, then remove the fuses of the components....etc

    Or just start with the fuses, but this means all of them, one by one.
    #2
  4. flearmonth
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    flearmonth New Member

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    [Feb 10, 2014]
    Might be a completely different issue but I recently had the same problem. After lots of investigation I discovered that my glove box light was on constantly. This had been happening ever since doing the dreaded broken hinge repair as the hinge piston no longer fully retracted and this is what switches the light on/off. It was a slow drain on the battery but if sat for a few days would flatten. Ended up disconnecting and problem solved. Worth a try if out of ideas.
    #3
  5. DieselJake
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    DieselJake God Mode

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    [Feb 11, 2014]
    Alternator's dodgy or something staying on and taking the juice.
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  6. pauldazzle
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    pauldazzle Active Member

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    [Feb 11, 2014]
    Check the alternator is charging first, & go from there.
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  7. MooLard
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    MooLard Member

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    [Feb 11, 2014]
    +1 check the alternator for supplying volts out of it's big wire as well as to the battery end when the engine is running.
    Also find the earth wires, make sure they are making a clean contact and that they are done up tight for good measure.
    #6
  8. DodgeT
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    DodgeT Member

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    [Feb 11, 2014]
    Just jumped it, started on 2nd go. Got a basic multimeter, put it across the battery whilst running, giving 14v, so assume the alternator is ok.
    Need a better meter now so that I can check for drainage.
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  9. Paul @ Unit
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    Paul @ Unit Active Member

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    [Feb 11, 2014]
    Alternator
    #8
  10. DodgeT
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    DodgeT Member

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    [Feb 11, 2014]
    Should it be charging more than 14v?
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  11. S4_dan
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    S4_dan Fire up the Quattro!

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    [Feb 11, 2014]
    Should be around 13.7 volts. So 14v is fine. Anything more than 15v and i'd be getting the regualtor tested.

    If the car is just left for a few days and it goes flat it could be the alternator regulator that is failing/failed. Had it on a bmw. I disconnected the alternator and monitored the battery charge level. It was allowing a feed back into the alternator, thus flattening the battery.....
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  12. DodgeT
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    DodgeT Member

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    [Feb 11, 2014]
    So, if I start checking the fuses, take it I can do it with them in place, ie sticking the probes in the windows in the top. What drain is acceptable?
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  13. DodgeT
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    DodgeT Member

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    [Feb 13, 2014]
    Used the car yesterday, morning and early evening, all was fine.
    Went to it this morning, it turned over slow, then immediately went completely flat, clicking all the dash etc.
    Would this point me to a certain drain / failure?

    (sorry for all the q's...)
    #12
  14. S4_dan
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    S4_dan Fire up the Quattro!

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    [Feb 13, 2014]
    What I would do is search youtube for 'battery drain' so you can see where to place a multimeter on the battery terminal and wire with ignition off and door locked (but open bonnet up!) and see what amperage the drain is. If it's high, then it's either a short or fault somewhere. Leave the car for 5 mins then test the drain, leave for 40 mins and test. Some components may not fully shutdown until after 30mins or so of car locking.

    If it's a low drain, it's possibly a light left on somewhere (glovebox, boot etc) or something isn't shutting down properly.


    Then it's pulling fuses whilst someone is in the car and you outside watching the multimeter to see if the amperage drops. If it does, then looks at what is on that fuse circuit.

    Dan
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  15. Mike_B
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    Mike_B Member

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    [Feb 13, 2014]
    Alternator! I had a similar problem on a Land Rover - turned out the diode in the alternator's charging circuit had failed, so allowing the battery to drain. (Think "one way" valve). I proved the problem by unplugging the alternator when I parked up and left it overnight, or at work - which was easy on the Landy, but as I'm not about to go look in the howling gale we have here right now, I can't comment on whether its easy on the Audi!
    #14
  16. demus
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    demus Fire in the hole !!

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    [Feb 13, 2014]
    Just had a similar thing with mine, the hazard switch going on and off when the car is locked.
    See if it does it when you just leave the car without locking it, if it only does it when locked it could point to the locking or alarm etc..

    The only thing I did was have a good look around, and look at the connections to the rear doors, in the pillars. You'll have to remove the rubber boot to look at them, touch wood it hasn't done it since.
    When the car was locked and everything had shut down the current draw was about 200mA, although measured with a clamp so maybe not too accurate at small currents..
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  17. DodgeT
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    DodgeT Member

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    [Feb 14, 2014]
    Been having a play with the fluke. Getting around 0.9 consistently

    photo.jpg

    Pulled all the fuses, 1 by 1 from the panel by the drivers door. The only ones which changed the reading were;

    #1 Air cond, which dropped it down to 0.7
    #15 inst cluster, which dropped it down to 0.6
    With both pulled at the same time, it dropped to 0.4

    Bear in mind that the air con hasn't worked for years.

    Guess I need to find a wiring diagram for the instruments, also have a look see if anything isn't working correctly.
    Interestingly, the fuel gauge works intermittently, but it's hardly worked for the past 5 years.
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  18. S4_dan
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    S4_dan Fire up the Quattro!

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    [Feb 14, 2014]
    Scan the instruments with vcds first, see if any faults come up.

    It's not a massive drain isn't 0.09 amps. My BMW drew a lot more than that when the alternator regulator had failed.

    Good luck in sourcing the cause.
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  19. demus
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    demus Fire in the hole !!

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    [Feb 14, 2014]
    Thats only reading 0.09, or 90mA, and really is a tiny draw. I'm guessing the hazard switch wasn't lit up at that point.
    have you watched it when its unlocked??
    #18
  20. DodgeT
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    DodgeT Member

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    [Feb 14, 2014]
    Doh, me and decimal points..

    Yeah guess it isn't a massive drain, but obviously enough to be causing problems if left over 12hrs or so.
    I actually have the hazard switch unplugged, it was my first "trial" a week or so ago, to take that out of the equation, so I really should plug that back in and see if things change/get worse drain wise. But, for the past week, it has still been draining over 12hrs without the switch connected.

    Now to find a friendly person local to north manchester who wont rape me for using vagcom..
    #19
  21. demus
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    demus Fire in the hole !!

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    [Feb 14, 2014]
    Maybe worth getting the battery checked, I'm guessing your battery is 70Ah or therabouts, so should support that drain for over a fortnight..

    Was that the total current draw on the battery? ie between the battery post and the terminal..

    9 times out of 10 if a battery is going to fail it will be during the winter, and usually show those symptoms, being a complete slug on a cold morning..
    #20
  22. DodgeT
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    DodgeT Member

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    [Feb 14, 2014]
    When the problem first started a few week ago, stuck a new battery on.

    yes, readings took between negative lead terminal and battery post.
    #21
  23. S4_dan
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    S4_dan Fire up the Quattro!

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    [Feb 15, 2014]
    Did you have the car locked when you tested for the draw? And did you check just after locking and again after 35mins?
    #22
  24. DodgeT
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    DodgeT Member

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    [Feb 15, 2014]
    Car was locked when did the initial draw test.
    Will do it again later at the two intervals as when I first locked it I hadnt isolated the battery.
    Thanks for the help btw.
    #23
  25. DodgeT
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    DodgeT Member

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    [Feb 15, 2014]
    Been for a run in the car, to make sure the battery is topped up. Got back, lifted bonnet, locked doors, battery isolated;

    Within a minute of car being shutdown

    View attachment 27614

    After 20 minutes

    View attachment 27615

    After 40 minutes (well actually more like 2 hrs, as I blew the fuse in the fluke while checking the battery - forgot to change the setting....) with a new expensive laser multimeter

    photo (2).jpg

    So, must of done something wrong with the checks yesterday, as 0.09amp was not bad, whereas 1.2 amp is pretty high.
    I'll go through the process of pulling the fuses again.
    #24
  26. DodgeT
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    DodgeT Member

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    [Feb 15, 2014]
    Been for a run in the car, to make sure the battery is topped up. Got back, lifted bonnet, locked doors, battery isolated;

    Within a minute of car being shutdown

    photo 1.jpg

    After 20 minutes

    photo 2.jpg

    After 40 minutes (well actually more like 2 hrs, as I blew the fuse in the fluke while checking the battery - forgot to change the setting....) with a new expensive laser multimeter

    View attachment 27619

    So, must of done something wrong with the checks yesterday, as 0.09amp was not bad, whereas 1.2 amp is pretty high.
    I'll go through the process of pulling the fuses again.
    #25
  27. DodgeT
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    DodgeT Member

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    [Feb 15, 2014]
    SO start pulling the fuses, and it's back to this for pretty much everything, no real difference with the #1 and #15 apart from a lot of fluctuation.

    photo (3).jpg

    Getting headache now...
    #26
  28. S4_dan
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    S4_dan Fire up the Quattro!

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    [Feb 15, 2014]
    Try disconnecting the Alternator. If the regulator has failed that will draw a bit of current. Remove all the wires, lock car and do the checks again...

    Dan
    #27
  29. demus
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    demus Fire in the hole !!

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    [Feb 15, 2014]
    I'd agree with the alternator, good place to start, might be worth pulling relays as well, not sure where they are but there will probably be one or more that switch on with ignition. Not unheard of for worn contacts to weld themselves together intermittently, keeping the switched circuit turned on.
    #28
  30. DodgeT
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    DodgeT Member

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    [Feb 16, 2014]
    Done the checks with alternator disconnected, no change.
    Going to drop it off at garage tomorrow, they've quoted max £40 for fault finding. Fingers crossed.
    Thanks for all the advice again, shall update with the issue.
    #29
  31. DodgeT
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    DodgeT Member

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    [Feb 18, 2014]
    Passenger door module apparently.
    #30
  32. demus
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    demus Fire in the hole !!

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    [Feb 18, 2014]
    Might be worth checking all the connections on it, some on my drivers door module had corroded slightly, the ones for the heated mirror...
    Check the connections to the door lock, and that it hasn't had a good soaking through all this dam rain...

    Let us know the outcome..
    #31
  33. DodgeT
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    DodgeT Member

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    [Feb 19, 2014]
    Got the car back. All is now good, about 50mA draw.
    #32

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