Strange goings on with the alternator. I have had the car 2 weeks, all has been fine, started the car up after finishing work and immediately had the battery not charging warning on the cluster display (this wasn't present on the way to work at all).

Attempted the journey home (and failed). Will be taking a look into this tomorrow, however I have a few questions

• As I understand, these cars have an intelligent charging system, if I meter from the alternator itself, should this always be ~14v, or can this be dynamically changed by the ECU at this position on the circuit?
• I would also like to check the fuse for the alternator, is this located on the battery terminal? and does this also fuse the supply to the starter motor?

Thanks in advance.

 

What is the age and condition of the battery? Many electrical faults discussed on these forums are the result of a failing or weak battery.

With the ignition in the OFF position, there should be a minimum of 12.5 volts across the battery terminals. If not, the battery should be replaced prior to replacing any other parts.

 

I think charging is like my car and PCM changes the voltage.

+1 it's likely the battery.

 

So, ran some tests, continuity back from the alternator to battery, ok
​​​​Charged battery outside of car, still not good
Pinched another battery from the sport age still no good
Replaced the alternator (with lots of swearing) all seems OK now, metered some of the diodes and they had failed. Just out this up for info.

Thanks for the help
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I had this exact issue between christmas and new year. car was fine, parked up and didnt use it for a few days. started it up and light was on. got down the road and broke down when the battery went flat. I checked the battery first but that did not help. here is the info from my testing.

Check voltage at battery with engine running should be around 14 volts. anything more and its over charging. anything less then 12.5 and its not charging. mine was around 12v but since fixing it its always around 14 volts now.

Mine was a diode in the rectifier, found a local guy who fixed mine same day for 100 quid with a new rectifier pack. Getting it off the car and back on however is a bit of a faff. My money is on the rectifier diodes same as mine.

 

Hopefully everyone is having the slip rings machined, replacing the carbon brushes and changing out the bearings at the same time as the diodes? It's worth the extra few bucks for peace of mind but also not having to remove the alternator again for quite a while since it's a fiddly job.

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