aussigazza

The battery in my TT keeps going flat over 3-5 days when parked.
Goes down to 6 volts.

Any commonly found problems?

Garry

AudiMick

Average car battery can deliver 50-60amp for one hour. Roughly, so at three days or so you have to be drawing 500mA- 700mA or so. 6-10 watts give or take.

TT should draw less than 50mA in standby. 40 days on a car battery.

Common problems.

Brake light switch stuck, leaving brake lights on, however that typically will take the battery down in 18 hours or so.

Aftermarket stereo , amp , powered sub woofer not switching off with ignition.

Cluster stays on.

Interior / glove box light not switching off.

After-run cooling pump, however like the brake switch this tens to take it down fast.

Aftermarket accessories including phone usb car chargers etc.

With the car in standby remove positive battery terminal , put an ammeter in series with the leads, you should see under 500mA until the car drops into standby and > 150mA then to >50mA.

If the current is higher pull fuses until it drops.

I had an aftermarket ipod interface that pulled around 300MA when supposed to be off, battery would die after a week if I didn't drive the car.

aussigazza

I checked the current draw at the battery and it dropped back to 80mA.

Opened the glove box and no light.

Unplugged light module and current draw dropped back to 29mA.

Globe was good, but no voltage at the light's plug.

Opened up the side and took out the switch.

No power at the switch.

Checked the No 3 fuse and it is good. Fog lights are off it and they work OK.

Interesting that the current dropped with the bulb out.

Double checked etc.

Cannot get voltage at the switch though.

If there is a short in the glovebox light wiring, you would expect it to short irrespective of the whether the bulb was in or not.

Got me stumped at the moment. More work for the weekend!

Garry

AudiMick

80mA is not enough of a draw, a good battery would take about 3 weeks to go flat at that rate.

Something else is happening.

aussigazza

I picked up the recharged and tested battery and it is back in the car with 13.12V or so.

I have a data logging DMM on the battery recording voltage every 4 minutes, as well as keeping the max and min Voltage.

Will check tomorrow after (cold) night and see what has been happening.

Will then recharge during the day and test the current draw overnight after that.

I have a theory about the current draw that I will investigate and document if it is what is happening.....

BTW, the glovebox light on the 2000 and 2002 (all I can guarantee) does NOT come on unless the headlights are on.

Any ideas that its switch may stick on and flatten the battery are wrong.

Garry

aussigazza

Bugger all voltage lost overnight.This is without the glovebox light installed:



Should last a LONG time!

Hump early on is interesting. No idea why this (can) happen.

I have more testing to do over the weekend.

Garry

aussigazza

Wife used the car today and I put the Glovebox light back in and logged the voltage drop over a couple of hours:



It is now losing about 0.2V over 3 and a bit hours.

Lost only 0.125V over 10 hours and 15 minutes or so when glovebox light NOT connected.

I have looked at the cabling diagrams in great detail and I think that there is a short in the glovebox wiring to a positive voltage.

This then drains through the Fog light relay, then the high beam lamp to earth. Will check this out over the weekend. I believe that the Fog lamp relay is staying on because of this short.

My fog lamps stay on when the high beam flasher is used. I do not see that they should by looking at the wiring diagrams.

Can someone confirm whether the fog lamps stay on when high beam is on or flashed?
Garry

aussigazza

Start of the weekend and I had charged the battery to over 13V.

Problem is not occuring after I put the glovebox light back in

I have therefore been logging both the voltage drop and current draw all weekend and only down to 12.9V with 0.24mA after 1.5 days.

All very linear and expected.

I may have corrected the short in puling on the wiring or the battery may be the culprit.

I will leave it all on for another day and see if things 'accelerate' as the battery loses charge.



Garry

aussigazza

The car drew 22 - 23 mA constantly from 13:19 Sat to 16:47 Sun.

Voltage went from 13.03 to 12.79 over the same period in a linear manner.

No problems apparently!

I will keep checking the battery voltage each night and see what goes on as my wife commutes.

Garry

reza.reza

Hi everyone,

I've got A4 2002 and haven't had problem so far. Last week parked the car and in the morning couldn't unlock the the doors by the remote control. Thought it was fob's battery, so changed it but still couldn't open the doors. Opened the door by key and realized that there is no electricity on the dash to start the engine, so jumped cable and it start pretty good. The story happened a couple of times and I thought maybe the battery is died, so bought a new expensive one. When I've set it up, it started the engine quickly, such a relief.
But tomorrow the same problem happened!!!! what the ....
I dropped the car to electromechanic and he checked t up with his instruments and computer. The car was in his garage for a night so he could have had a chance to figure the problem out!!
He said, no problem at all and he didn't have any problem starting the car in the morning and from his computer's results, everything's fine!!! By the way, my radio is broken and a CD is got stuck in it. So he just removed the radio's fuse in case if that was the battery drain cause.

Brought the car home and it was very good during 3 days. But on Sunday afternoon I put back the fuse in and parked the car on Monday. On Tuesday the story started again!!! Couldn't start the engine even with jump cable and Booster!!!! Electrician came to help me but he was also confused. The starter works and the engine try to fire up but it can't (looks like there is no fuel)even the tank was full we added some more and also dragged the car with another car. When he was dragging the car the engine fired up for a minutes but when I removed my foot from the clutch and pressed the accelerator to keep the engine revs, the engine turned off again!!!!

Sorry for the long story, but I had to explained to make it clear!

I'm a student in Sweden and a bit scared of expenses of this damn problemsss.

Will be appreciated if any of you guys have got any ideas??
I saw some previous thread that Fuse or Fuel pump might be the reason but why the battery diessssssssss?????

Thanks again and waiting for your helps.