Battery drain.

[Coops90]

Hi chaps.
Posting on behalf of a friend here.

He's got an e30 318i m40 and something is draining the battery horrendously quickly. There is a sound system in the boot, but we have checked all of it and don't think it can be that.
There's a brand new Bosch battery in it, so it can't be a dodgy one. When the car is jumped, the battery charges fine. Disconnect the red terminal and it holds charge. As soon as I reconnect the red, the voltage plummets at an alarming rate.
I have been told that it could be that the alternator is drawing charge, but I have tested it on the casing and I don't seem to be getting anything from it.

Any ideas what it could be?

Thanks,

Pete.

[capnmchl]

The simplest solution is to connect a test light between the battery and a terminal, and start pulling fuses until the light goes dimmer. You can also unbolt the main live to the alternator/starter and test those two this way.

[daimlerman]

With your meter across the battery terminals,pull each fuse in turn until you find the culprit.

[Coops90]

Cheers chaps.
I've tried the pulling each fuse out but no change. I'll try unbolting the main live to them both now.

[Coops90]

Really pissing me off now. Can't seem to get to the bottom of it. Doesn't seem to be the starter or alternator.
Pulled each fuse out 1 at a time. Seems two fuses are part of the problem. The interior lights and one other (can't remember which the other is) but it seems everything is draining it. Ugghh.

Anyone got any more ideas before I just torch the thing?

[toby]

Fook it - walk away from it for a bit if it's pissing you off. Although that's easier said than done.

Disconnect that stereo system first and eliminate it - or have you tried that?

Interior light circuit? Is the boot light staying on after it has closed?

What's the other circuit?

This can be fixed man!

Have you got a multi-meter by the way?

[Coops90]

It's the fuse 2 along from the interior light. Can't remember which it is exactly.
I've disconnected everything to do with the soundsystem and also all the 3 different live terminals one at a time. Definitely not the soundsystem. According to the voltmeter, the two fuses I mentioned make the voltage drop very quickly. But two there seems to be other things draining it on top of that. And it seems to be intermittent which confused me further!
Reallllyyyy testing my patience.
I haven't checked the boot light, I will do Wednesday when I'm back down with the car.


Thanks for the tips, much appreciated.

[Supafly]

I had a drain which I traced to the central locking control unit. All sorted now but was a nightmare to pin down.
Keep at it and stay logical and it'll be sorted

[Brianmoooore]

Dead easy to track down, but you must approach it logically and progressively.
Don't forget that there is supposed to be a battery drain, but just not an excessive one.
Easiest way is to pull ALL the fuses, connect the meter in series with the battery negative lead, record any current flowing, try all the fuses one at a time, recording the current flowing through each one.

[Coops90]

Thanks chaps, going to try the methodical approach Wednesday.

Pete.

[Coops90]

Right.
Took all the fuses and relays out. Still a drain. So with the 3 positive terminals, the two removable bolt-on terminals aren't a drain really. But the main fat one is. A lot. I can't seem to trace it because it goes into the main loom.
Anyone any ideas what it could be?

[Shaheenk]

do you have a pic of the terminals you have on the battery ?

You say it goes into the main loom, is this on the battery side or the engine side ?

The main battery cable from the back to the front drives 2 components , the starter and has a link off to the Alternator, the small cable along with it drives the ECU power and Fuse box environment .

If you have an aftermarket system have you checked your amps are actually switching off when you turn the stereo off , is there a possibility that whoever fitted it could have tapped off the main loom for power.

Do you have power cables from the amplifers in the boot (assuming there are amplifers) to the battery ?

A dead short would be the only thing to pull a significant amount of current , that and the lighter which I recall is on the same fuse as interior lights.

[Brianmoooore]

If the excessive drain remains when just the largest cable (the one that actually has the clamp on it) connected, then disconnect the medium thickness red wire from the back of the alternator (B+), and check again. Be careful not to let the disconnected wire touch anything, or you will get large sparks when you reconnect the battery!
If this cures the drain, then your alternator (main part, not the regulator pack) is faulty.

[Coops90]

Everything connected to the sound system has been removed.

It's the one on the right which my middle finger is supporting. I think it might join the black box:

I've taken the fat one off the starter and there's no change.

I'm fairly useless with electrics!!

[Brianmoooore]

The thick black wire connected to the battery clamp goes only to the outer 8mm stud on the starter motor, with another medium sized wire going on from there to the B+ terminal of the alternator.

[Coops90]

Brian mooooore is correct again!!

I took the fat one from the alternator off, reconnected the clamp. It dropped by about 1 amp but the stayed there and didn't change. Whereas before it would plummet to 1.

I have changed the alternator too, so they both mush be faulty?

Thanks chaps.

[Coops90]

Turns out two cables touching on the alternator caused it to drop. So thats that sorted.
But now the car wont even turn over.

I've tried touching the two pins together to make the starter spin, but it wont. The relays on the bulkhead just click and the starter doesn't. When turning the key, the same thing happens. But every say, 10 minutes, the starter will clunk once and then nothing again for another 10 minutes.

Is it worth changing the starter?

Just seems to be one thing after another!!

[Grrrmachine]

Sounds more likely that the battery's completely flat.

[Coops90]

This was even when it was jump-connected to another car.
Is it worth just leaving it charging for a while then? And then coming back to it?

[Grrrmachine]

You have to be careful that, in all your fiddling, you haven't done something daft like loosened a battery terminal. But yes, an overnight trickle charge will do wonders for a flat battery if it's not already on its last legs.

[Coops90]

Lovely. Thanks, I'll give it a go this week then.

Apparently, the car started first time when jumped this morning, ran for 15 minutes and then died.

[Coops90]

My battery charger seems to have broken!

But I just jump started it, left it to run for 25 minutes. Rough as a dog. But whilst it was running, the voltage on the battery jumps up and down between 11 and 13.
I then turned the engine off. Turned the key, nothing. The voltage drops to 4 when the key is turned and then returns to 11 or so when the key isn't in the ignition position.

Heres a video to show what i mean:
[youtube][/youtube]

[Shaheenk]

Ur Alternator is stuffed, it should be at a constant 13.7 - 14V.

you right that sounds rough, my guess would be alty first, could just be the voltage regualtor but that is not working the way it should.

Due to low voltage you could have an issue where the coil does not have enough juice for it to run smooth.

[Supafly]

Get your battery charged first and see if it will hold its charge. Then once started check your car for any parasitic drains. Always worth sorting through these things with a logical approach. I've had more than my fair share of head scratching and swearing with these things!
Good luck

[Coops90]

I'd forgotten about this thread! I need to get the car sorted really, so going to spend some time on it.

I got the battery checked and its knackered. Will hold 14v but has no cold crank power at all which would explain the non-starting.
id changed a few spade/ring connector things on the alternator and starter because they looks horrifically ropey.

Thanks for all the tips and suggestions chaps, its much appreciated.