NEWCASTLE BROWN

driving home tonight quite normally when all of a sudden steering light,battery light and hand brake light came on, RAC man open bonnet said alternator had gone, is it normal for these lights to appear because in the past when this has happened it has only been the battery light .

STI_Baly

iTrader: (23)

The electric system needs a minimum amount of voltage to function when the power drops below this level it's common.

A recent example would be a 2.0 focus ghia i had and when voltage dropped below 6v (faulty alternator here btw) the ABS, Traction light would comeon these require the most power then once below 4volts the whole clock lit up dim and needles started resetting.

I would suggest putting the battery on charge straight away though. Don't let it sit flat for to long.

Good Luck

Baly

scoobian

it would run off the battery till IT died, showing only the red ignition/charging light
so you SHOULD have had some warning, I would have thought

joz8968

iTrader: (13)

Yeah. it's strange for a alternator to suddenly 'go'. The brushes or diode packs normally wear and, as you say, the battery light starts to flicker on/off very faintly at first... progressing to fully lit... then the car ultimately dieing.

NEWCASTLE BROWN

sorry for confusion i meant on car i have had in the past,not this one. but still it still serms strange for the alternator to just go. thinking back on it when i've had the radio on it has been humming strangley BUT not like a noise that matches the revs of the engine

STI_Baly

iTrader: (23)

They don't just pack up unless something breaks internally it's wear and tear (as mentioned earlier)....the only way to actually know a alternator is begining to fail on older cars is to test it with a multimeter. We only tend to find out when the thing starts to let us down as that's when it becomes most apparent. Or it may be the way your car is wired?

Majority of new cars will now actually show the battery light when the alternator drops below a certain voltage, as majority of new alternators are controlled/monitored by ECU and Battery light plugged into ECU.

joz8968

iTrader: (13)

Is the heathy, correct voltage at the alternator's output terminal supposed to be 14V?

scoobian

about that....13.8v is normally shown on meters
it needs to be a good 1v above battery voltage to get a charge current flowing

STI_Baly

iTrader: (23)

Yes - With the engine at a fast idle the voltage on the meter should read around 13.5 to 14.4 the alternator needs to generate a larger voltage than the batterys rated voltage to overcome the internal resistance of the battery

If the reading on the meter is less than 12 volts then you may have a failed alternator

You could measure the above over the battery terminals.

I hope the above helps.

PS....not all alternators are 14v rated some are 12v and if you do not look at the spec and by a smaller one rather than a 14v you will face problems....

Another test you could do to ensure alternator is ok is to turn on A/C, heaters, headlights, Rear screen, Hazards and wipers to see how the Alternator copes.

NEWCASTLE BROWN

thanks for everyone input by a chance conversation turns out an old friend had on from a scooby he broke, cam and fitted it for £50, me happy again

STI_Baly

iTrader: (23)

Now thats a bargain.....Good Luck fella.