My battery has a habit of going flat, 

It's only about 6months old (same was happening with the previous battery). 

 

I became suspicious of a parasitic draw on the battery so I checked it out with a meter in line with the battery (neg' terminal). I pulled all the fuses one by one but the drain remained regardless (350mA).  I also pulled my radio just in-case. 

 

Switching on interior lights raised the draw as expected but making sure everything was off and doors shut still 350mA.  It's also a new meter. 

 

Feeling stumped, any advice?

Disconnect the main feed to the alternator, you might have a "leaky" diode in the rectifier pack 

@Blueb4sunrise - When you first switch on, does the battery light come on? If not, then your problem is with the alternator control wires.

Thank you for your input guys.

I tried as you suggest nige8021 and disconnected the alternator (I did this at the fuse for the black wire that sits on top of the battery, I tested the current draw on the battery again and its still measuring just over 350mA (0.36A on the 10A scale). 

 

Hi ken, If I put the key in the ignition and turn it to 'on' all the warning lights switch on then go out except for the parking brake and battery lights... When I start the engine the battery light switches off. Just for good measure I took two voltage readings across the battery with the car idling: all electrics off= 14.2 volts, all electrics on= 13.8 volts. The battery put out 12.9 when the car was off. 

 

Can I assume from this that the battery and alternator are in reasonable health and therefore rule them out as the root cause of the problem?

 

Check glove compartment light, boot light, vanity mirror light not on, pull bulbs if necessary.

The battery drain will initially be of that order until all the systems shut down to standby mode, not sure how long you have to wait, 10 minutes, half and hour?

 

Leave the meter connected and look later on, make sure the bonnet is closed and the doors locked.

12 minutes ago, Blueb4sunrise said:

Can I assume from this that the battery and alternator are in reasonable health and therefore rule them out as the root cause of the problem?

 

Yes, I think so. 

Next things to try are to disconnect each of those other strip fuses, and the three green blade fuses, one by one and see which of them is conveying the current. 

If you tell me what year the car is, I can probably tell you what each of those fuses does, later.

Big red cable is probably everything interior, so a good one to rule out.

1 hour ago, Blueb4sunrise said:

If I put the key in the ignition and turn it to 'on' all the warning lights switch on then go out except for the parking brake and battery lights... When I start the engine the battery light switches off.

Yeah, that's normal function, and it's something it costs nothing to check with a current drain.

Here's a Tech bulletin from VW on how to check for battery drain vw.tb.27-07-11 Battery Discharged Diagnosis for Static Current Draw.pdf

4 minutes ago, nige8021 said:

Here's a Tech bulletin from VW on how to check for battery drain vw.tb.27-07-11 Battery Discharged Diagnosis for Static Current Draw.pdf

Ah, thanks for this.

I haven't let mine 'go to sleep'.  I will test it again over the weekend following the proper procedures. 

360mA is a lot more than I'd expect to see just because things are awake instead of asleep. 

Ok, I left the meter connected while the car sat for 2h 20mins exceeding the recommended 2 hrs.  The current draw had reduced to 310mA . 

 

The only variable which may have confounded this experiment is the fact that I had to manually lock the car because the central locking is temperamental and 'decided' to be broken this evening.  The current draw did drop by 50mA so I am going to assume that the car did actually go to sleep- it also rose to almost 500mA after I unlocked it suggesting that it 'woke up' once I unlocked it. 

 

P.s. when I first approached the car to take a reading the key was left in the house. 

 

Is it possible that the car never truly sleeps if the central locking is goosed? 

Edited 12 April, 20197 yr by Blueb4sunrise

On 12/04/2019 at 14:32, Wino said:

 

Yes, I think so. 

Next things to try are to disconnect each of those other strip fuses, and the three green blade fuses, one by one and see which of them is conveying the current. 

If you tell me what year the car is, I can probably tell you what each of those fuses does, later.

Big red cable is probably everything interior, so a good one to rule out.

I finally got round to some more testing.  I did as you suggest and and tried undoing those other fuses next to the alternator one.  

 

When I undo the large red one (which I believe is for all the internals) the current drops right off.  I think this one goes into the car to the relay panel under the dash by the drivers knees. 

 

I pulled the panel and tried unplugging each relay one at a time in case there was one stuck on or something... still no change. The current draw drops off when I pull the 30A fuse with the green top which sits underneath the double relay but I have no idea what this fuse is for. 

What year is the car, and what engine code, AUQ?

Got a photo of the relay panel?

Ignore the arrow (I nicked the photo from google) but what is that green fuse on the bottom right for?

3 minutes ago, Wino said:

What year is the car, and what engine code, AUQ?

Got a photo of the relay panel?

Sorry ... it's a 2000 Skoda octavia 1.8t I don't know the engine code.

I have a funny feeling that might be a self-resetting thermal fuse for the electric windows?

Edited 18 April, 20197 yr by Wino

Scratch that.... I found this sticker in the boot. 

Its an AGU

Yeah Power window fuse 

That's saved me a lot of looking though pdfs, cheers Nige. Looked familiar from my mk2 Golf days.

3 minutes ago, Wino said:

That's saved me a lot of looking though pdfs, cheers Nige. Looked familiar from my mk2 Golf days.

It should be to the right of the position indicated in the pic, but Position B on the early ones wasn't allocated and on the May 02 > it was for vacuum pump in position B and pos C for the windows

Edited 18 April, 20197 yr by nige8021

Does this fuse also protect the central locking mechanism? 

I just answered my own question. 

Went out, pulled the fuse and it kills the central locking and windows. 

 

I have had weird locking and window stuff happening since I've owned the car....

While it does go to all the window motor modules the power for the C/L is via fuse 14 

2 minutes ago, Blueb4sunrise said:

I just answered my own question. 

Went out, pulled the fuse and it kills the central locking and windows. 

 

 

It will as the window modules also do the switching for the C/L so without it's main power it will also kill the C/L