PLEASE help with chronic battery drain

[ThomasP]

Hi all

Car 55reg 1.9tdi iz5 241,000 miles still going strong.

The purpose of the post is to try and get some good advice regarding a substantial battery drain on the above car. There is no doubt that this car is the best I've ever owned but for about two years + now it has suffered from a SUBSTANTIAL battery drain ie. between 1.9amps and about 0.8 amps. There are two things at the moment that don't work that is the driver's door lock which I am just about to repair and the boot switch which gave up the ghost a long time ago.

 

I have taken the car to all sorts of recommended people but no one can actually tell me what is wrong. I have tested the battery and alternator as much as I can and they both seem good.

I have been told a couple of times now that because the boot switch and door lock are not working then this could be the source of the drain because the car never actually 'sleeps' as it is waiting for the status signals from both the boot lock and door lock and because it is not getting any response then this is causing the battery to go flat........... If I use the car every day I can just about start it in the morning with the battery nearly flat. If I leave it a day the the following day forget it, the battery is as flat as a pancake.

 

 

Whereas the explanations I have been given are very plausible it does occur to me that for a battery to discharge almost fully overnight (battery is a 72aH battery) is much more of a drain than might be expected from the car as it looks to sleep. Surely, that kind of draw would be fairly minimal. If I disconnect the battery the battery is as fresh as a daisy when I connect back up in the morning. I have no warning lights but on examination two of the glowplugs are not working but as you will know engine management light doesn't come on until all four are dead - It still starts then

 

 

I would really appreciate any advice or help to resolve this problem as it is spoiling what is, otherwise a great car still.

 

 

I hope someone can help

Thanks etc

 

Tom

[Breezy_Pete]

Have you tried disconnecting the alternator overnight to see if that eliminates the draw?

Should be a fuse somewhere you can remove. Fuse No. 1 on the front face of the E-box, I think.  It would be wise/safe to disconnect battery negative before unbolting this fuse, or the wire to it from the alternator, then reconnect battery negative afterwards.

 

Don't start the car with the alt disconnected.

 

Edited 22 January, 2019 by Wino

[langers2k]

I know it's not really the time of year for messing with cars, but you might want to consider following the guide for finding parasitic current draw.

 

Basically, you need to fool the drivers door and bonnet sensors so they think they are shut. Lock the car with both open and with the ultrasonic alarm sensors disabled, Wait for about 2 hours then by measuring the voltage drop over each fuse you should be able to narrow down what's consuming the current.

 

There is a PDF in this post which explains the method in more detail:

 

 

 

[ThomasP]

Wino/Langers

Many thanks for the quick replies

 

Wino....I have tested the alternator as much as poss but I haven't actually done as you suggest.... I will do that and report back

Langers ...thanks for info

 

Tom

Edited 22 January, 2019 by ThomasP
Oh, by the way - Engine is a BKC

[DJSmiley]

Alarm? 

 

I know there is a know issue with the alarm siren, when it fails it just drains your battery. (Siren lasts 6 years on paper.)

 

Also, some people have issues with the brake light switch (brake lights randomly lit, so eventually your battery will be flat)