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Hi. I have a 2003 RS6 Saloon. 77000 miles

Yesterday the battery light came on in the outside lane of the M25, followed a minute later by loss of all power, leaving me stranded without hazards until the police stopped all the traffic to get in onto the hard shoulder!!! (luckily the traffic was just rolling at the time)!

Anyway, AA man said battery was flat, only 8Volts. Started the car off another battery - fine - but no charge coming to the battery.

We both thought it was the alternator! He said he had worked on another car ages ago and thought there may be a huge fuse (200Amp) which protects the battery from overcharging?? but left it at that and I got Relay to get me home.

Have charged battery overnight and starts fine but only shows about 11Volts on the dial and doesnt vary with revs or anything. Do you think this is a classic alternator packing up or more to it?? Also, anyone any idea of cost? cheers

Sounds like alternator to me. They seem to fail frequently about this mileage. Mine did.

Maybe someone has another idea?

Hi. Did your alternator just go suddenly then without warning then resulting in a very flat battery very quickly? I was surprised that it went flat so quick and that the battery light hadnt come on much earlier.

I've been on vagcat site and found this: http://www.vagcat.com/epc/cat/au/RS6/20 ... 7/3700155/
which shows a 200A fuse. This is what the AA man said. A bit more digging and some people have suggested that the fuse can blow just due to age and the metal deteriorating. Doesnt mention where the fuse is located. I may have a look around the fuse box. Worth a shot!

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Definitely worth checking, but I'd be surprised if it was this easy.

Oh sorry. I registered. Just a username and password required. Its great for diagrams and part numbers.

I would bet that the fuse is in the engine compartment as you wouldn't put that big of fuse in the passenger compartment because to get that big of fuse to blow you have to generate a lot of heat. I hope for you that it is the fuse as I have heard off this forum that the engine has to be pulled to get at the alternator. Maybe I'll take a look at mine today and see if I can find the fuse.

You can change the alternator without removing the engine, but you've got to disconnect an oil pipe, I believe, so it could get a bit messy.

There is a fuse. It's called a "main fuse". It's under the expansion tank.

My alternator failed at the same sort of mileage.Pretty instant-everything just died!
Cost about £600 IIRC.

Mine died at 80k. £600 for an independant to do it is pretty standard. Its a fairly tight job requiring a bit of moving of pipes. Just make sure that they dont upset the intercooler hoses whilst doing the alternator. Mine were ruptured while they were doing the alternator and the total cost came to over £2k as it required new i/c and all new hoses. God bless the warranty man!!

jd_hants wrote:Yesterday the battery light came on in the outside lane of the M25, followed a minute later by loss of all power, leaving me stranded without hazards until the police stopped all the traffic to get in onto the hard shoulder!!! (luckily the traffic was just rolling at the time)!

jd_hants wrote:Did your alternator just go suddenly then without warning then resulting in a very flat battery very quickly? I was surprised that it went flat so quick and that the battery light hadnt come on much earlier.

I have exact same thing tonight. Battery showed on the dash, than the power V went down very quick.

What was the solution to your problem jd_hants ?

I seem to remember him changing the alternator shortly afterwards.

Yes, Audi diagnosed the alternator. Replaced at £700 - fine now so I guess that was the problem.