Battery Light on 330Ci

[Patrick Bateman]

Bought the car with the red battery light on but the battery seems to be charging ok and haven't noticed any particular problems. Increasing the revs doesn't cause the voltage to spike which suggest the voltage regulator is ok?

Checked via. the instrument cluster if this paints a clearer picture-

Key in position one, battery reading 12.5v, start the car, voltage initially drops to about 10.5 then climbs back up to 14+ in a couple of seconds (alternator voltage now yes)?

Stick on all lights electrics etc. etc. and the voltage eventually drops to a low of 11.8.

A friend (ex-BMW) reckons you'd want to see at least 12.5v with all the electrics on although he's in Oz so can't have a look, his ex-work mate will do next week though. Likely to be the alternator itself? Loose connection?

[wolf1]

Alternator has had it get a new one.

[Patrick Bateman]

To update, that 11.8V was at idle, all electrics etc on while driving saw 13.7V.

[Patrick Bateman]

Alternator replaced and the battery light remains on. Battery shoes as 78% and 'good' according to a test meter.

Checked the voltages through the instrument cluster and they remain unchanged. What else could it be?

[LukeSi]

Patrick Bateman said:

Alternator replaced and the battery light remains on. Battery shoes as 78% and 'good' according to a test meter.

Checked the voltages through the instrument cluster and they remain unchanged. What else could it be?

Bugged instrument cluster?

[maniac0796]

Has the wire from the dash to the alternator broke somewhere.

What chassis model is it, E46 or 90?

[Patrick Bateman]

maniac0796 said:

Has the wire from the dash to the alternator broke somewhere.

What chassis model is it, E46 or 90?

It's an e46.

I didn't see myself, a BMW mechanic was working on it and he's lost, he'll be getting in touch with a sparky, don't know whether he checked the cables or not.

[Chainguy]

maniac0796 said:

Has the wire from the dash to the alternator broke somewhere.

What chassis model is it, E46 or 90?

I had this on a 325 E46. As above, it was the wire having broke that goes from the alternaor to the dash.

It came on just after I'd went down a pothole you could have hid 3 Jap soldiers in. It came to the mid point of my calf muscle, but the rainwater was hiding the depth of it. I got a buckled alloy as well for my trouble.

Thanks for feck all Glasgow City Council.

[Patrick Bateman]

Mmm that would make sense, allowing some but not enough current to flow.

Twice I've noticed since I bought it last month the dash lights have dimmed momentarily but nothing else.

[Patrick Bateman]

With the key in position one the battery voltage shows as 12.3V according to the instrument cluster. When starting the car it dips to 10.6V then rises up to a steady 14V with nothing on.

It is only when at idle and everything on it seems to read low.

Different people keep saying different things, what a PITA.

Also, low oil warning light keeps coming on for a few seconds after I start the car then goes away. I had the sensor renewed and the same thing happens, would that be inclined to point towards a specific issue somewhere in the charging system?

Edited by Patrick Bateman on Monday 3rd October 00:43

[Patrick Bateman]

Sparky had a look at it today. I thought it was just a friend of the mechanics but it's one of the BMW guys as well so that was kind of handy.

He's pretty sure it's the instrument cluster that's fked although this particular guy also has access to the BMW GT1 diagnostics so he'll get it plugged in and see what's what for definite.

[Chainguy]

Patrick Bateman said:

Sparky had a look at it today. I thought it was just a friend of the mechanics but it's one of the BMW guys as well so that was kind of handy.

He's pretty sure it's the instrument cluster that's fked although this particular guy also has access to the BMW GT1 diagnostics so he'll get it plugged in and see what's what for definite.

Not cheap. I had a 320 that developed pixelation, and that was in the £100's to get fixed

[Patrick Bateman]

Good news but also facepalm news.

It was a fuse.

A fking fuse!!!

I wish I'd been told to check that before spunking on a new alternator. Still, I'll remember to check them first now.

[Patrick Bateman]

Well a BMW mechanic did think the same...

Although I'm not sure the reason the voltage dips in the 330 but not in my compact. In the compact the voltage stayed constant no matter if headlights etc. were put on.