Couple of electrical niggles...

[macas]

Just bought another convertable and the battery light is on with the ignitio off and keys out,but it goes out fine when engine is started?
Also electric windows only work when the drivers door is open??,any ideas boys,i cant work it out!

[macas]

Right,iv sorted it so now tge windows work when both doors are open,but the window switches dont light up when you pull the headlight switch to the first position,surley there isnt a second fuse controlling the windows that could have blown?

[macas]

Right,windows are sorted....

Just the battery light on now,anybody come across this before?

[Barx325i]

that is a weird one and shouldn't be.. so if you leave it for any period of time the battery light is still warning of no charge?

[Barx325i]

the only immediate 'fault' I can think of, based on standard wiring is, is your ignition barrel loom/switch..

[macas]

When you turn the ignition to position 1 the battery light is on,postion 2 it goes off when the other dash lights are on.then when i start the car the battery light goes out,so is charging normally,but when i take the keys out it still stays on!
I probably would not be bothered but i dont want the light to drain the battery overnight...

[Barx325i]

sounds like the igition ring isn't returning to its home point.. Very odd but if the rest is standard...

[macas]

But the battery light should come on when you switch ignition lights on?it actually switches off at this point?

The ignition ring is returning because the stereo swithes on in position one but turns off when ignition is in tge completely off position,its s a weird one!

Thanks for the replys my friend,very much appriciated!

[Barx325i]

the battery light is on with the ignitio off and keys out

is this the case?

[macas]

Yes,thats whats happening,theres no point in even having a look myself because i wouldnt know where to start!!

[Barx325i]

so you take the keys out and return in the morning and the battery charge light is still lit?

[macas]

Well iv just bought the car today,iv left it for a couple of hours ,came back and its still on.

[Barx325i]

remove the ignition cowling & stuff

Find the ignition ring and if possible test as appropriate with regards to logic.. Sadly this is my only slant of fault diagnosis given the circumstances, work backwards and listen to 80's indie tunes - it worked for me

[macas]

Haha!!...yeah i will have a bash myself tommorow,il start with that!...i just seem to make stuff worse when i start taking things apart!...
Thats it,slow and easy wins the race.

Thanks for your help anyway:)

[macas]

Right,my battery is charging exactly 13 v,is this correct?
I always thought that it should be charging at around 14?

Also,what voltage should the battery be at when tested disconnected,(i know this sounds stupid because its a 12v battery)but im sure it should read 12.4....12.5to be a good one?

[Brianmoooore]

The battery light (or any other filament bulb) lights when there is 12 volts on one side of it and zero volts on the other. Doesn't matter which way around these are.
It doesn't light when there is zero volts on both sides of it OR 12 volts on both sides.
This latter case is the normal state of affairs when the engine is running - it has 12 volts on one side of it generated by the low current output of the alternator (blue wire) and 12 volts on the other side as well from the ignition switched battery positive (green wire).
When the car is parked up, there should be zero volts on the blue wire (because the alternator's not turning) and zero volts on the other side because the ignition switch is off.
If your car has the light on when the car is parked, then the first test is to connect a volt meter across the blue and green wires (can be at the bulb itself), and to establish which wire has 12 volts + on it, when it should have zero.
I suspect that in your case it will be the blue wire.
The large terminal on the alternator (red wire) is permanently connected to the 12 volts +of the battery, but this voltage is prevented from reaching the blue wire by the rectifier diodes in the alternator.
If I'm correct, one of these diodes has become leaky, allowing the voltage to reach the blue wire and the battery light when the alternator is stopped. The other side of the bulb isn't connected to zero volts, but the path to earth through all the ignition switched circuits when they are off is of sufficiently low resistance to allow the bulb to light.
The leaky diode theory would also account for your lowish voltage readings.

[macas]

Thanks brian(i think)

I will do a test tommorow,i take it this would mean an alternator replacment?

[johnl320]

As Brian said, alternator diode leakage is the most likely culprit, stick another alternator on it. had this issue a couple of times in the past.

[macas]

I have a e34 2.5 alternator knocking about,is it just a case of swapping the pully over,i know it definately fits size wise?
Thanks for all your help so far!

[macas]

Thanks brian and all that has replied,just changed the alternator as all is good!!!