Help my battery is discharging....

Type_R · 26 Mar 2011 at 10:08

..well woke up yesterday to find the car not unlocking and looking rather lifeless. So reverted to the old style method of lock and key and it was fairly clear all the electronics were dead. Got myself a new Bosch battery weighing 18.75Kg :eek:

and fitted it. Straight away everything fired up, drove a few miles and back.

This morning, car is dead again. Checked the battery only 7V left in it. Called the RAC who came and tested the battery, 100% healthy (so at least Eurocarparts sold me a good battery!). RAC man found a 7-10Amp drain on the battery when the car was switched off. He had no idea what it could be, all the lights inside and outside the car seem to be turning off correctly. He was also unsure of the shut down procedure on a MK5 Golf as to when things shut down and hence when to expect the battery to be left alone by the car.

So I am left with a new battery with something draining it around 7-10 Amps. Nothing in car configuration has changed and the alternator is supplying 13.9V to the car.

The car is a MK5 Golf GTi 2005 - Electronics inc heated & electronically controlled front seats, electric folding mirrors etc.

Any ideas what the next step is to finding the problem? Would VAG-COM help diagnose? I have disconnected the battery for now..but looking for options.

Maz · 26 Mar 2011 at 10:48

You haven't left an interior light on have you? Haha

mattyprice4004 · 26 Mar 2011 at 10:55

Probably the alternator is keeping it's coils energised, which causes the drain.

The alternator needs a magnetic field in the outer coils to operate, and this is obviously meant to be switched off when the engine is stopped. The relays can jam on, causing the drain.

Get a multimeter and check the alternator connections for current drain, I reckon it'll be there. 7-10A is too much for interior / boot lights, but about the right amount for this. When it happened to me, it pulled about 11A but it was a huuuge alternator.

Dangerous Dave · 26 Mar 2011 at 10:56

The MK5 Golf shuts systems down over the course of around an hour so you should measure the load after 1 hour.

Have you fitted a RNS510 sat nav unit ? as when running newer firmware with an older canbus controller causes the unit not to shutdown fully.

Best bit is to wait an hour and then measure the load and start pulling fuses one by one, I would start with the stereo even if you are just running the normal system as I have read of a couple where they caused excessive battery drain as they weren't fully shutting down.

Type_R · 26 Mar 2011 at 19:30

Thanks for the response guys. I have an Alpine 9815R unit which I fitted about 3 years ago, it always switches off with the key out the ignition. RAC man said the drain was too much to be the radio. I am going with the alternator theory.

How do I test for the alternator draining once the car has been off for one hour? Also can the relays be fixed or is it a new alternator I will need?

EDIT- the alternator for my 1K1 -AXX engine is 140A and costs £299 for a Bosch one at Eurocarparts! Good thing I know someone with a trade account!

Dangerous Dave · 26 Mar 2011 at 21:33

Checked mine and straight after turning the engine off it is pulling 6 amps, 90 minutes later it is pulling almost nothing. I assume the only thing left running is the alarm.

CocoPops · 26 Mar 2011 at 21:54

I'd go with a Canbus issue.

That was my first thought as soon as I saw MK5 GTI.

Where are you, is there anyone local with VCDS/VagCom to check?

Type_R · 27 Mar 2011 at 08:42

I'm in Bham. Yeah will get my local independent Autovolks to check it out and take it from there.

Thanks Dangerous for taking the trouble to check on yours, much appreciated.

Type_R · 27 Mar 2011 at 18:03

I forgot to add, might help, when I restarted the car after 2 occasions of the battery being dead the following dash lights came on:

Steering wheel - amber
ESP - amber
Tyre pressure sensors - amber
Handbrake - red

They all disappeared as soon as I set off driving the car. Could the lights indicate the problem? The engine light never featured.

bandit · 27 Mar 2011 at 23:33

easy way to reduce the likely suspects is to check voltage while pulling fuses and seeing if there's any changes...

Type_R · 28 Mar 2011 at 10:53

bandit said:
easy way to reduce the likely suspects is to check voltage while pulling fuses and seeing if there's any changes...

I guess I need to get a clamp amp meter for that. I doubt my 10A multimeter will be up to the job of checking drain!

Have booked it in to Autovolks to check it out on Wednesday.

Myshra · 28 Mar 2011 at 10:56

Type_R said:
I forgot to add, might help, when I restarted the car after 2 occasions of the battery being dead the following dash lights came on:

Steering wheel - amber
ESP - amber
Tyre pressure sensors - amber
Handbrake - red

They all disappeared as soon as I set off driving the car. Could the lights indicate the problem? The engine light never featured.

AFAIK all VAG cars do the lights on trick following a battery drain / replacement, I figured it was their way of telling me they had forgotten their past settings. This has been my personal experience with them at least.

Type_R · 28 Mar 2011 at 11:06

Myshra said:
AFAIK all VAG cars do the lights on trick following a battery drain / replacement, I figured it was their way of telling me they had forgotten their past settings. This has been my personal experience with them at least.

Yeah I'm sure this is the case. I was hoping that as the red battery light does not feature it's not the alternator that has gone wrong.

Type_R · 29 Mar 2011 at 12:23

Just had a look at the car manual. There are two fuse boxes, one next to the battery in the engine bay and one in the car under the dash. Now I am assuming that as the amp being drawn are greater than 5A then it can't be a fuse rated less than 10A which is the culprit? Is this interpretation correct? There are loads of 5A fuses and I don't want to start pulling them if they cannot be responsible.

I was also thinking that (unless its the alternator) it must be something that I cannot see in operation i.e. not a light. Would the side view mirror demisters draw this much off the battery, as I do remember using them last week. The switch is off, but who knows if the switch is working! Is there a simple practical test to see if they are left on when the car is switched off (as the manual does not highlight a separate fuse for the power mirrors/demister).

Lashout_UK · 29 Mar 2011 at 13:22

Touch them?

Type_R · 30 Mar 2011 at 09:17

Lashout_UK said:
Touch them?

Well they don't seem hot to touch.

I gave up and having just been to Autovolks (who cannot look at the car till the afternoon because they are quite busy) have called Leader Automotive (car electrical specialists apparently) to come and have a look at it. £25 call out charge and £29 per hour. They reckon they can diagnose the problem within the hour usually. I hope so!

Type_R · 30 Mar 2011 at 11:16

Just had them come and check the car. They located an electrical noise coming from the rear drivers side, which turned out to be a faulty Fuel pump controller : 1K0 906 093 D --> 1T0 906 093 F

I think the Made in Romania on the unit might explain a few things! They have pulled the fuse out for it at the moment whilst I try to locate a new one (few about in the Country it seems). £95 + VAT from VW.

EDIT - The Eurocarparts price was just the relay. Not what I am looking for!

Ordered the part now waiting to pick it up in London on my way back this afternoon!

Type_R · 30 Mar 2011 at 16:21

Fitted the new Fuel controller unit. The noise has gone when switching the car off so I am hopeful all is well again.

Changing it was a simple task. Thanks for all the help guys.

Type_R · 1 Apr 2011 at 02:05

The part in the end cost me £88 inc VAT from VW (clearly the £95 + VAT included some monies for middle men!). Took 2 mins to fit and the car has been back to normal (smoother feeling although I'm sure it's just placebo!) since.