Odd battery drain problem.

[nimmy]

Hello

I have a very perculier problem that has been bugging me literaly years.

Back story, I'll try and be as quik as possible:

I have an Audi 44 B5, which, after a couple of years suddenly started with a battery drain problem. Neither I nor the garage could find any problem with a multimeter/ test lamp. Eventually after two for three years of trying I just ended up stareing at the multimeter in complete puzzlement, at which point I saw it surge to 700 - 1000 mA, I watched it more and notice it was pulsing at regular intervals. I had no idea what it could be so I started pulling fuses, eventually finding it was fuse 15 (instrument cluster and a few things); I also pulled all the relays but the pulse still kept going; by pure accident I had the multimeter in line of sight with the cluster and it turned out that the surge was caused by the minute hand moving of all things.

I got a second hand cluster and replaced the old, unfortunately this did not cure the problem. So, the surge is caused by the minute hand moving on, but it's not the clock or instrument cluster itself but the clock must be triggering a surge elsewere. I could just pull the fuse everyhting I park, but this resets the odemeter to 0 and who knows what else.

Has anybody on here ever had this experiance or heard of it? Has you can appretiate it's sending me nutty trying to track it down.

Long shot I know, but thanks for your patience.

 

[tazz]

Thats one hell of a pulse 1 amp.....I can not see a clock drawing 1A, But possible the cluster 12v/5v regulator could be faulty....you need to go through all electrical equipment one device at a time...other possibilities are, central locking actuator or controller, security alarm system, electric aerial.

 

[nimmy]

Thats one hell of a pulse 1 amp.....I can not see a clock drawing 1A, But possible the cluster 12v/5v regulator could be faulty....you need to go through all electrical equipment one device at a time...other possibilities are, central locking actuator or controller, security alarm system, electric aerial.

Thank you for your quick reply,

Yes it is one hell of a pulse times by 60 an hour, but it's deffinatly the the minute hand that does it.

The cluster 12v/5v regulator interests me, as does the conteral locking actuator, Vag com does give the 'possible' leak error.

Thanks.

 

[ian.settle1]

Are you using the meter correctly to obtain this current reading?

 

[monjoor]

My brother had a similar problem in his Golf. There was a constant drain of 700mA. It took the garage quite some time to find the fault. The fault was a damages wire shorting to ground.

 

[nimmy]

Are you using the meter correctly to obtain this current reading?

Yes, I'm using the amp setting, plus the garage did the same test and I watch how they did it, there was no result due to the pulse.

thank you for your reply.

 

[nimmy]

My brother had a similar problem in his Golf. There was a constant drain of 700mA. It took the garage quite some time to find the fault. The fault was a damages wire shorting to ground.

Hello, I do hope it's not a wire thing that would take ages to find, however, this isn't a constant problem but it surges every minute so it's deffinately the minute hand that triggers it.

Inspired by the post by tazz, and having my memory prompted, I did exchanged the altinator regulator few months after getting the car (brushes were getting worn), thinking back the problem did seem to happen after that, so I will look in to that today.

Thanks.

 

[Gazthesparky]

Do you have Bluetooth phone connectivity in your car? It's a common problem in audis where the module goes faulty and causes battery drain as the module doesn't switch off .

Not known if to pulse but worth a try

 

[nimmy]

Do you have Bluetooth phone connectivity in your car? It's a common problem in audis where the module goes faulty and causes battery drain as the module doesn't switch off .

Not known if to pulse but worth a try

I don't have a bluetooth phone.

I'd would have like to have checked the altinator regulator but audi have put it in a stupid place that either needs the timing belt off to remove the altinator or remove the inlet manifold.

Thanks.

 

[ian.settle1]

Yes, I'm using the amp setting, plus the garage did the same test and I watch how they did it, there was no result due to the pulse.

thank you for your reply.

How did you have the probes connected

 

[nimmy]

How did you have the probes connected

Disconnected the earth, put the positive probe to the earth of the battery and the negative probe to the negative battery strap.

I swaped out the old cluster for the second hand one I got and that has a voltimeter on it, that was reading 15.5 volts when the engine was on; I have had some cluster bulbs blowing so I don't think the regulator is working to well.

 

[plugsandsparks]

15.5 volts !!! - I would double check with your multimeter across the battery with the engine running at 1500rpm. If you get 15.5 , your regulator / diode pack has gone and it will start to damage other stuff so act fast...

 

[nimmy]

15.5 volts !!! - I would double check with your multimeter across the battery with the engine running at 1500rpm. If you get 15.5 , your regulator / diode pack has gone and it will start to damage other stuff so act fast...

Yes, it was a false alarm. I went to get some petrol after I posted that and the volt meter was peg on 14 volts there and back.

But I will do that check you suggest, thanks.