Constant battery drain

[den310]

I recently saved a 2004 A3 2.0TDi sport from being scrapped by my non mechanically minded brother to hopefully fix up and the first problem I want to address is a constant battery drain of around 1.7 amps when everything is off.

I took out each fuse one at a time to try and narrow it down but no significant drop noticed so wondered if anyone else had similar and what was it?

A scan showed an issue with the steering and convenience unit, I don't have the exact log at the moment, will have it scanned again soon to see what it showed exactly.

It did have the usual problem with the micro switch in the boot catch but that has been resolved for a while.

Can anyone suggest what to take out of circuit to help find the battery drain or any other suggestions?

Thanks.

[den310]

Found what it was thanks to a mechanic friend of mine. The battery drain when the car is left unlocked is quite normal so me leaving it in the garage unlocked for over 3 days drained the battery. I put the meter on the battery and locked the car. within a minute the current drain went from 1.7 Amps to 500mA and would have dropped more I think but I unlocked the car again and it went back to 1.7 Amps.

 

[Magnet]

That's interesting Dennis, since I have left non-Audi cars unlocked in the garage for weeks and not suffered any undue battery drain. 

Probably others more up to date on these things will confirm that indeed your diagnosis is spot on with Audis of your model year, but I'm not so sure. 

Whatever it is that is draining the battery when the car is 'left unlocked' has a wattage of around 20w  ( 12 X the 1.7 amp) - equivalent to the current drawn by a brake light or indicator bulb - no mean drain! 

Having pulled all ( and you are sure there aren't any other fuses e.g. In-line etc) without reducing the the current drain, my suspicion was that perhaps someone had connected something up direct to the battery perhaps and not via. a fuse at all, but, if you have solved it , then you have solved it. 

With regard to the 1.7 amp draw before locking :- I wonder if this is due to the courtesy lights still being on (as normal) until the car is locked or of course the lights have timed out automatically.  Your 1.7 amp current draw could equate to the wattage of the set of interior lights. 

Reducing to 500mA ( half an amp) once locked ? You are right in your assumption that ...'would have dropped more..' and I believe a figure of more like 50mA would be what you would expect to run a 'fully shut down' system , after say 45 secs. after locking. 

If it were mine, I would double check that there is still a current drain of 1.7 amps in the unlocked condition well after the courtesy lights have gone out. No doubt you probably have Dennis, and that would mean I am still rather confused - but not too difficult with me! 

Kind regards,

Gareth.

[den310]

Hi Gareth

Thanks for your reply. The current drain of 1.7 Amps stayed constant for quite some time when unlocked and after any courtesy lights had long gone off. I am not sure if fully solved but my friend was right about the current drawn will drop when locked but yes I will still investigate further. There is nothing extra connected to the battery but there is one of those parrot Bluetooth phone things in there which takes it's power source from the fuse box inside the car, I will remove it as not keen on it but I didn't suspect that has been any issue.

Will update further as and when i get further with it.

[Magnet]

Thanks Dennis,

I would check that the current draw does indeed settle to around 50mA after being fully locked up for a couple of minutes. Much more than that will be undesirable. 500mA is obviously too much. 

Kind regards,

Gareth.

polly Parrot thingy?  - yes, I would be disconnecting that too, but only after doing the above check first. 

[den310]

Ok had another quick look today and the current drain remains at around 500mA after locking the car and waiting a while. I tried it with the fuse for the center convenience unit out and no change. I cannot remove one at a time when the car is locked so that makes things tricky. The parrot bluetooth thing only comes on when the igntion is on so that's not a problem so something is drawing around 0.4 to 0.45 Amps.

I do have an issue with the ESP and steering as the lights are on the dash. Just waiting to get the code reader again to get the errors logged in VCDS.

[den310]

Meter reading when locked and after 10 minutes.

[Magnet]

Hello Dennis,

Um, aporox. 500mA. ( half an amp) draw then. That's equivalent to around 5 to 6 watts - not insignificant.

Daft-things first checks.

Remove glove box bulb incase micro switch is not switching off. Same with boot light, but I would remove one at a time and test, otherwise you won't know which is the culprit if the current draw falls. 

Sat nav? Known these (boxes) to cause such issues if in the boot and moisture has got in and created 'white rust' deposits on the printed curcuit board. Unplug? 

Just a couple of extra pointers. Useful though??

Kind regards,

Gareth. 

 

[cliffcoggin]

I'm clutching at straws here, but Gareth's comment about moisture ingress reminds me that another correspondent on the forum said that A3s have a reputation for poor seals on the fuse box lids, so possibly there is a short in there.

[den310]

12 minutes ago, cliffcoggin said:

I'm clutching at straws here, but Gareth's comment about moisture ingress reminds me that another correspondent on the forum said that A3s have a reputation for poor seals on the fuse box lids, so possibly there is a short in there.

I don't think there is as all looks OK but I will bear that in mind when doing even more investigating. Thank you.

 

1 hour ago, Magnet said:

Hello Dennis,

Um, aporox. 500mA. ( half an amp) draw then. That's equivalent to around 5 to 6 watts - not insignificant.

Daft-things first checks.

Remove glove box bulb incase micro switch is not switching off. Same with boot light, but I would remove one at a time and test, otherwise you won't know which is the culprit if the current draw falls. 

Sat nav? Known these (boxes) to cause such issues if in the boot and moisture has got in and created 'white rust' deposits on the printed curcuit board. Unplug? 

Just a couple of extra pointers. Useful though??

Kind regards,

Gareth. 

 

Thanks Gareth. I haven't checked the glovebox light yet but will do. The boot light is missing as my brother removed it in the past thinking it was that setting the alarm off, I have not seen it in the car so can rule that one out. No satnav in there either. all extra pointers appreciated as it is easy to miss things.

[Magnet]

Looking back Dennis, it seems the current drain has reduced from 1.7 amps to 0.5 amps, and yet you haven't found the culprit. Are you absolutely sure the 1.7 amps was 'real' at the time of measuring? - car fully shut down and no courtesy lights on. 

0.5 amp drain will run your fully charged battery down in a few days or so, so is significant, as I said. 

Well worth following Cliff's lead and checking everything for water ingress and damp - very valid point. 

I'm still confused that this drain still remains after removing every fuse one by one and not finding the offending curcuit. Are you sure there isn't another/other fuse boxes within the car? There are often more than one. 

Good luck and kind regards,

Gareth.

OK No sat nav. CD changer? (on Cliff's damp logic) 

[den310]

23 minutes ago, Magnet said:

Looking back Dennis, it seems the current drain has reduced from 1.7 amps to 0.5 amps, and yet you haven't found the culprit. Are you absolutely sure the 1.7 amps was 'real' at the time of measuring? - car fully shut down and no courtesy lights on. 

0.5 amp drain will run your fully charged battery down in a few days or so, so is significant, as I said. 

Well worth following Cliff's lead and checking everything for water ingress and damp - very valid point. 

I'm still confused that this drain still remains after removing every fuse one by one and not finding the offending curcuit. Are you sure there isn't another/other fuse boxes within the car? There are often more than one. 

Good luck and kind regards,

Gareth.

OK No sat nav. CD changer? (on Cliff's damp logic) 

Yes the 1.7 Amps reading is what I get when the car is left unlocked but nothing on and keys out. That still happens. The drop then changes to around 0.5 Amps when the car has been locked and wait for around 30 seconds maybe. The fuse boxes I have tried are the one in the engine bay and the one end of the dashboard. Will be looking at all suggestions again and checking by removing fuses one by one again. I leave the meter on and get a real time reading.

 

[cliffcoggin]

Dennis.

I decided to start from scratch and reread this thread in case I missed something. All I can come up with is:

[1] I have no idea what a parrot thing is, but if it is some sort of home fitted device I would suspect that first. Rather than assume it draws no power  because it does not work when the ignition is off, I suggest you disconnect its power supply to be sure. There may be a battery charging or memory circuit inside the device that requires constant power. It may even have a fault that isn't obvious.

[2] Are there any other non factory accessories? Disconnect them.

[3] You said the boot light has been removed. Was that just the bulb removed or were the wires cut? Are there any naked connections left that could short out?

[4] The only thing I know of that draws power when the ignition is off and the car locked is the alarm system. I don't believe it draws half an amp in normal operation but perhaps it is faulty. I don't know how you could test it though.

[5] If none of the above isolates the problem I see no alternative to taking out each fuse one at a time and measuring the current drain. (Unless I missed an earlier comment I think you said you had not done that.) It will be a slow business but could be speeded up by taking out half a dozen fuses at a time until you find the right group, and then just one at a time from the offending group.

[den310]

10 minutes ago, cliffcoggin said:

Dennis.

I decided to start from scratch and reread this thread in case I missed something. All I can come up with is:

[1] I have no idea what a parrot thing is, but if it is some sort of home fitted device I would suspect that first. Rather than assume it draws no power  because it does not work when the ignition is off, I suggest you disconnect its power supply to be sure. There may be a battery charging or memory circuit inside the device that requires constant power. It may even have a fault that isn't obvious.

[2] Are there any other non factory accessories? Disconnect them.

[3] You said the boot light has been removed. Was that just the bulb removed or were the wires cut? Are there any naked connections left that could short out?

[4] The only thing I know of that draws power when the ignition is off and the car locked is the alarm system. I don't believe it draws half an amp in normal operation but perhaps it is faulty. I don't know how you could test it though.

[5] If none of the above isolates the problem I see no alternative to taking out each fuse one at a time and measuring the current drain. (Unless I missed an earlier comment I think you said you had not done that.) It will be a slow business but could be speeded up by taking out half a dozen fuses at a time until you find the right group, and then just one at a time from the offending group.

Thanks for your reply.

(1) The parrot is a Bluetooth hands-free device for a mobile phone. I have disconnected it fully and found no change.

(2) No other added non factory accessories added.

(3) Boot light with holder removed, wires are insulated.

(4) I have removed the fuse for the alarm system, no change.

(5) I will be doing this again, I did do it but may have missed one or more so will write a list and check them off one by one to be sure.

[Magnet]

Hello Dennis again, 

I'm in grave danger of boring you and everyone else with this! 

Something has come to mind which might -just might - throw some light on the 1.7 amp draw when the car is left unlocked. 

I notice your A3 is 2004.

We have a 2006 one, and that has 'automatic lockdown' if left open (without keys in it) for more than 30? seconds. i.e. The car will automatically lock itself. I now wonder if some curcuitry holds the car in the unlocked condition and obviously uses power to do so- this power reducing to around 50mA when fully locked and the alarm has set. Incase it comes as a package, this car also has speed lock (or whatever your call it) whereby the car automatically locks itself once on the move. Our car is a basic model, so its fair to assume all 2006 A3s had these features. 

Question? Was your model year fitted with this facility? Does your car automatically lock when on the move? If it automatically locks when on the move, should it also automatically lock itself if left unlocked? 

We need the knowledge of others to let us know if this feature applied to 2004 examples as well. Or may have been an option. Anybody know? 

If it was originally fitted with this feature then your 1.7 Amps could be associated with this feature permanently 'holding' this car in the unlocked condition when it shouldn't. Possibility?? 

Of course, this does not  account for your 0.5 amp draw when locked, but might - again just might- be associated. 

Kind regards, 

Gareth.

[den310]

Hi. Sorry for the delay, other stuff happening. This car does automatically lock after a minute (or less, not timed it) I think if unlocked and then no door has been opened.

Can anyone tell me what circuits are on the fuse links on the front of the engine bay fuse box? I guess one may be to the alternator but don't know about the others. I ask as may have to disconnect them one at a time to see what happens.

[cliffcoggin]

Judging by the size of the cables and the fuse ratings (80-100 amps) they have got be the starter motor circuit, and possibly the alternator.

[den310]

Yes that will be another, the starter motor circuit (probably the 200 Amp fuse?), the alternator and there are 3 more.

[Magnet]

Hello Dennis,

Apologies - it's 'oh not him again'! .

Taking another look at your facts and logic, and I see that the car is fitted with an automatic lock down or whatever it is called. What now confuses me is that in one of your early threads you mention the 1.7 amp draw when the car has been left unlocked in the garage. I must take it you left the keys in it, otherwise it would have automatically locked!  Intersting point, but I wouldn't have thought it would have consumed that amount of current  if left with the keys in it and it didn't lock, but..

Can we take it you have the handbook to identify all the blade fuses and their curcuits? 

Large amps fuses? I too think alternator etc., but personally I don't think I would remove these - concentrate on all locations for blade fuses first.

If that fails? I may be talking through the part which should be used for sitting, but alternators and diodes? Is it possible that a diode can fail 'closed' curcuit as opposed to open curcuit, and if so, would this result in a drain back through the alternator? Just another thought! 

Kind regards,

Gareth.

[den310]

Hi Gareth.

All input is welcome. 👍 When I left it unlocked in the garage it was after having it running. I don't think it locks itself then, only when you unlock and not open a door after 30 seconds or a minute or whatever time it is.

Yes I have the handbook and a Haynes manual so can identify all blade fuse locations and what they do.

I did wonder about the alternator and did disconnect the small wiring connector and no change but I need to test with all wiring disconnected. Will be down the garage tomorrow to do more testing.

 

Thanks.

[Reddevil1607]

Hi lads bit late to reply but I’ve just had the AA out my battery keeps going low had it replaced last week but there’s a 5 amp drain on the battery can anyone help 🤷‍♂️

[Magnet]

Hello Keith,

A 5amp parasitic drain means that the battery is likely to run flat in less than 24 hours if the car is not used. That is a phenomenal drain, and equivalent to something running a wattage of around 60w - equivalent to at least 10 sidelights being left on. 

I think you will better understand what needs to be done if you read the threads, but you will need a meter obviously capable of accepting/ measuring currents around 5 amps. 

Be interested to know how you measured your parasitic drain. 

Kind regards,

Gareth.

[cliffcoggin]

Keith.

In the absence of any useful information about your problem and what you have tried to resolve it, I echo Gareth's advice. If you don't have a meter rig a test lamp to test each circuit.

Alternatively, remove each fuse one at a time and find what effect that has on your battery capacity.

[Davedental]

Hi Keith

I have a 2005 8PA Sportback 2.0l petrol and have exactly the same problem. The battery went flat after 3 days of not being used. I connected a meter between the earth terminal and lead and it registered 1.1A . I thought this was probably the interior lights. I went back to the car later and found the current drain had increased to 5A!! This may be intermittent. I have pulled all the fuses in the engine compartment but have run out of time to check the dashboard fuses. I will post any findings tomorrow

[Steve Q]

1 hour ago, Davedental said:

Hi Keith

I have a 2005 8PA Sportback 2.0l petrol and have exactly the same problem. The battery went flat after 3 days of not being used. I connected a meter between the earth terminal and lead and it registered 1.1A . I thought this was probably the interior lights. I went back to the car later and found the current drain had increased to 5A!! This may be intermittent. I have pulled all the fuses in the engine compartment but have run out of time to check the dashboard fuses. I will post any findings tomorrow

Good luck with your investigations into the issue Dave, and welcome to the forum 🙂