Time for a new Alternator (Update: New Battery)
 

Well it seems to be the warm weather has upset the S8 a little.

Went to drive it today and it had a little trouble! Jumped it OK (Anker Jump Pack highly recommended as it starts a 4.2!) and drove from that point fine over a 20 mile test route.

Started OK after that and seemed to be back to normal. Looking at VAGCOM I am only getting 12.5v when running on the measuring blocks (The 2.8 A8 gets 13.7v as a comparison), confirmed this also with the good old multimeter.

It seems the S8 has lost a couple of vital volts when running.

Battery is good (tested) and is in fact a reasonably new Yuasa Silver, so do not expect that to be the cause. Therefore it looks like a new alternator is needed to me. Now the old one has done nearly 199,000 miles so its best years are behind it and provided good service.

What's the Alternator of choice?

Euro Car Parts have a Lucas (150A Model - 401441231) one for £335 using there daily magic codes or CarParts4Less for £287.

Though Gloucester does have a specialist that reconditions starters and alternators so may try that instead.

Make sure you get a V8 one. Many parts outlets sell the V6 one claiming it's the same as the V8. It'll bolt up, but the cooling air inlet is in a different place.

Thank you and good to know.

Last time I did an alternator was on a C4 2.8 Quattro

Yuasa Silver battery? Don't commit to an alternator at this stage as I've had loads of issues recently. Let me dig out the thread and I'll report back...

(Too long, didn't read) summary - it was the battery, local auto electricians tested it and it was useless, 8.5V under 300 amp load.

Here's my thread detailing the problems I've had recently with alternator/battery/electrical distribution connector block on front chassis rail...

http://forum.a8parts.co.uk/showthread.php?t=15074

Hope this helps in some fashion.

Interesting read and thank you.

Seems the battery may not be as good as I thought.

I will swap it round with the one in the A8 and do some further testing.

My car now starts like an excited puppy, barely a revolution of the starter motor and off she goes, desperate to go somewhere. Before the battery was replaced and after all the 'testing', it was sluggish and took around 8-10 revs of the starter motor. The worst attempt took around 6 seconds, and no wonder really with the Yuasa showing just 8.5V under load when tested.

After the auto electricians recommended a new battery, I took the option of swapping my Yuasa Silver for a spare battery out of a Ford Focus C-Max (no-name brand job). Took a bit of jiggery-pokery as the battery is about half the size and I had to raise it slightly and support it to get the battery terminals clamped. This battery had been sat for 5 months and it fired up the Audi in an instant. I was then able to transport myself and the car in order to get the new Bosch battery fitted.

Cheers.

Spent some time with the car today and can confirm the root cause of the problem is the battery.

Therefore I cannot personally recommend to anyone a Yuasa Silver battery.

More interestingly I tested it again this time with an Autel Battery tester (AL539B and recommended as I bought it specially for this as the cheap battery tester thought my battery was good) and it confirmed on the CCA test it needed to be replaced. It also confirmed that charging from the Alternator was all OK from the car. The readings I had originally on VAGCOM were down to the battery not the condition of the alternator, hence it was not taking a full charge.

Went to take it back to Halfords and to rub salt into the wound they refused to replace the battery as it tested fine on their machine. Battery had a 5 year warranty, was well within that and I had the receipt.

But hey there you go a lesson learnt.

I will write to Yuasa to see if there is any interest from them as its all in a little disappointing.

Strong, very strong, letter to Halfrauds required.

Just wanted to provide an update on this one. Since replacing the Yuasa Silver battery with just a basic one the car has been perfect.

All the problems of a flat battery after a few days, not charging and just being a headache have disappeared.

Car has started quickly and perfectly when required, it’s been been left for a week or two without a problem and has done many cold cranks without fault.

+++

I'm really pleased that you've got your battery issue sorted. Mine was nearing the end of the warranty period and had already been replaced once in that time. There was certainly a reluctance to offer a replacement as I didn't have the original paper receipt from 2014. It probably wouldn't have been readable as the thermal paper-type receipt had lightened considerably over time.

It does annoy me that even with proof from an independent auto electrics specialist that the battery was shot, Halfords claimed that their testing (with a Yuasa-branded tester) showed that there wasn't any problem. I left my dud silver Yuasa battery with the local Halfords branch and asked the manager to call me to discuss replacement. No phone call received.

Yuasa Black
---------------
Not sure if anyone else saw those 'Yuasa Black' batteries being offered with a lifetime warranty but these disappeared from their stores/websites pretty sharp-ish with no explanation. I tried to buy one in the middle of last year. Something fishy going on there, methinks.
Original non-working link for Yuasa Black battery: http://www.halfords.com/motoring/bul...2v-car-battery
I've also attached a screenshot of the email confirming the order but turned up to discover that there was no battery and no-one knew or claimed to know anything about this fabled lifetime-warranty battery for £180.

My A8L is currently very happy running on silver Bosch juice.