Porsche Enthusiasts Club Forum

I noticed the other day when driving home that my centre console volt meter was reading low at about 10.5v I checked the output and multimeter shows 10.7v, I thought it would be a simple case of new regulator but after fitting it voltage output is still the same, I’ve noticed my battery light isn’t lighting at all, even when the ignition is turned on, is this connected? Electrics baffle me so any advise would be appreciated. Oh I did notice the stator appears a bit worn when changing the regulator.

OK first things first. Does the alternator warning light come on at all? Check/replace the bulb. Find the warning light wire & disconnect it from the alternator and earth it to a good earth. It should light. The other side of the wire is connected to ignition live.
The ignition warning light is part of the exciter circuit for the alternator, so no light no charge.
If this checks out then alternator off for a check by an auto electric specialist with a test rig.
When you say you replaced the regulator did you replace the brushes as well (some are integrated with the alternator some aren't). It could be brushes but they don't generally fail suddenly, they more generally fade away.

Changing the regulator in place is a bit fiddly, sometimes takes 2 goes to get it in right,

But it it’s in square and no charge, it could be the rectifier pack gone pop, were the brushes worn out completely

My regulator brushes gave up instantly, no warning

Alternator bulb doesn’t light at all, I’ll check the bulb. The old regulator bushes were not really worn. I’ll try as suggested. Does anyone really refurbish alternators anymore? We used to have a local Lucas dealer who did but not sure who does now.

Yes I have a place local to me that does

Just have to trawl the Internet, have to take into consideration a new Porsche alternator is over £700,

Or if you fancy having a go, Wood Auto sell all the bits you need to rebuild it like new

https://www.westlancsautoelectrics.co.uk/

this happened to me last week in the middle of nowhere conveniently outside the only garage for miles with a lift.

The bolt that holds the belt tensioner had either snapped or fell out. When cold fine getting nearly 14v, once warmed up the belt became slack and the volts dropped off to 10.7.

I would check your tensioner arm first...

Had to replace mine last year - tried the regulator replacement but as Waylander said the rectifier diodes can also fail which requires the alternator to be rebuilt / reconditioned.

I got my replacement from CP4L and was an original Bosch alternator which is rebuilt by Lucas and comes with a test report in a Lucas box.

https://www.carparts4less.co.uk/p/lucas-alternator-401330101

Well I need a new alternator or rebuild this one, tried a new bulb, earthed the feed, no better so I decided to strip the alternator and found one of the copper wires broken and missing from the stator windings where it joins the bit that the brushes run on.
Thanks for everyone’s input.

Pic of wire.

That's knac.... fu.... broken then.
The Bosch alternators are pretty bomb proof TBH. Just thank yourself luck its a little cheap one. The one for the Cayenne is water cooled & is around £750 from a refurbers! It is also reckoned to be a major PITA to change!

And we’re back on the road, took a risk on a genuine Bosch alternator on eBay for £25! Perfect.
Sometimes things work out well...for once!
Thanks for everyone’s input.

Hope you fitted a new regulator before installing in the car

I put the new one I’d bought onto it, so hopefully it’ll last a long time.