One evening, a couple of days before Christmas and about 2 miles into a town drive the red battery warning light came on. In the old days this meant (i) a broken drive belt, (ii) dodgy alternator or (iii) a loose connection. According to the driver's manual that's all it means today too !
After a few miles the light flickered and went off...then it came on and ... er, off. My mission was important so I decided to take a chance and carry on. This went on for about 30 minutes and I carried out an electrical shut down routine - no aircon, headlights off, no radio, no fan and even used the handbrake when stopped so as not to light up the brake lights. When I parked up at the station to collect someone I kept the engine running but had to switch off when I went into the station.
Crossing my fingers (the battery is 7 years old) I started the car later quite easily, the battery warning light had gone and now after several drives I haven't seen it on except at start up as usual.
Should I forget about it (but I do have a 1000 mile trip to do in France in a week or two) or do I do something.
All connections are tight, the drive belt is still there and taut and without the engine running a multi meter shows 12.5 -ish volts across the terminals and when running about 13.8 - 14.2 volts, so the alternator is working - or at least now it is.
By the way, how long would a diesel car keep going without the battery being charged - the fancy electronics will be using up juice even though there are no spark plugs ?
Last edited by: Dulwich Estate on Tue 27 Dec 11 at 18:54
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Difficult to give an accurate diagnosis if every thing is ok.However the alternator fitted to this engine has an over-run drive pulley which in simple terms means it has a one way clutch.A very common problem on these is for the clutch to slip and thus the drive to the alternator shaft is reduced,causing the charge warning light to illuminate.The pulley can be replaced on its own at about £60 for the part.As for how long the battery will keep going on its own is very dependant on battery condition and load.A 7 year old battery is not going to last very long.hth
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First thing i'd be looking at is brush wear and condition, when they neared end of life they would sometimes show intermittent non charging like this.
Used to be able to replace brushes quite easily not so long ago, either individually or as part of a brush pack simply screwed on the back.
Is there a competent sparky in your neck of the woods who you would entrust such a thing to if you don't want to delve deeply inside.
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>> One evening, a couple of days before Christmas and about 2 miles into a town
>> drive the red battery warning light came on. In the old days this meant (i)
>> a broken drive belt, (ii) dodgy alternator or (iii) a loose connection. According to the
>> driver's manual that's all it means today too !
>>
>> After a few miles the light flickered and went off...then it came on and ...
>> er, off.
Was it raining that night?
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"Was it raining that night?"
Well, yes, I suppose it was a bit. There was some mist about too. Do you think parts of the alternator got damp and then dried out ?
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>> "Was it raining that night?"
>>
>> Well, yes, I suppose it was a bit. There was some mist about too. Do
>> you think parts of the alternator got damp and then dried out ?
>>
Possibility of belt slip.
I would get a new one put on.
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Thanks all. I've since driven maybe 250 miles - motorway and town, and started it 15 times or more with absolutely no re-occurrence of the dreaded red light.
I'll ask my man to take a precautionary look when it next goes in for a service in about 6 months.
In the meantime I'll keep on going.
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Audi A4 B6 - 04 1.9D Red Warning Light (intermittent) - Battery - carmalade
