Battery Light On, No VCDS codes. 11.9V with engine running.

[lincoln_dj]

Hi guys,

Car is a 2004 S4.

Battery light came on on the way home today. Ran VCDS, no fault codes showing. The battery shows 12.1V with engine off and 11.9V with engine running.

I'm fairly sure this points to an alternator failure (which is covered under warranty) but wandered what else it could be or anything else I should look out for first. Corroded/lose cable or anything? If it's just a loose cable etc then that ISN'T covered by the warranty! lol.

TBH I've not had much of a look round the engine on these things, so no idea even where the alternator is at the minute without googling so hopefully someone can point me in the right direction of what to look for!!

Cheers in advance!

Adam.

 

[benjie]

I would straight away say alternator as voltage should be 14.2ish when running.

If it's under warranty, I would just take it in and describe the problem and ask what they're going to do about it. Will they charge for diagnosis? If not, just take it in.

 

[NHN]

Apart from checking cables which I doubt have come loose tbh, then sounds like either battery or alternator to me, you could try disconnecting battery, charging it up with say a ctek charger & then see if it holds voltage or drops.

 

[AlexGSi2000]

Definatley points to the alternator this one.

 

[BRILLO]

As above.

 

[dualmono21]

yes again i would say the same
the alternator is the oly thing that is connected to your auxillary belt on the front of the engine
be carefull as there are 2 differant types .... be extra carefull in the fact that not a lot of people are aware that the alternator is actually water cooled ...water and electricity dont mix well !!!!

 

[hades-]

yes again i would say the same
the alternator is the oly thing that is connected to your auxillary belt on the front of the engine
be carefull as there are 2 differant types .... be extra carefull in the fact that not a lot of people are aware that the alternator is actually water cooled ...water and electricity dont mix well !!!!

water cooled ?

 

[dualmono21]

water cooled ?

yes thats correct
the alternator on the b6 and b7 s4 is 190 amps as standard and because of the power output it has to be water cooled

 

[Audi Doodah]

yes again i would say the same
the alternator is the oly thing that is connected to your auxillary belt on the front of the engine
be carefull as there are 2 differant types .... be extra carefull in the fact that not a lot of people are aware that the alternator is actually water cooled ...water and electricity dont mix well !!!!

I thought a water cooled alternator sounded ridiculous too but you're right. Bizarre!

 

[lincoln_dj]

hi guys, thanks for all the replies!!!

The belt has snapped. Hopefully it's just wear rather than the belt having snapped due to alternator failing...