Dying alternator?

[RaymondReddington]

Having some strangeness with my ‘08 1.9tdi. Replaced the cambelt and then started getting the battery light coming on occasionally. The light will come on whilst driving and will clear if you switch off the car and restart it. A multimeter confirms that it stops charging when the light is on, 11.96v vs 13.62v with the light off at idle. My first though of course is that the ‘nator is on its last legs, but it does seem odd how a restart makes it work again?
Anything else it could possibly be?

Thanks in advance!

 

[theViTALiTY]

Where did you test for charge, at battery terminals or alternator?

 

[RaymondReddington]

Where did you test for charge, at battery terminals or alternator?

Battery terminals.

 

[desertstorm]

Likely to be the regulator on the alternator. They have the brushes attached and you will probably find the one brush very worn so it is just touching the slip rings on the alternator. When you stop the engine the brush makes contact again. At low rpm the brush can maintain contact at higher rpm it will float.

 

[RaymondReddington]

Thanks, that makes a lot of sense. Sounds like I’m fitting a new ‘nator then.

 

[prt57]

On my 05 reg Skoda Fabia, the alternator light would only go out when the car was given some revs from a cold start. No charging when the light was on.
Replacement alternator sorted it out.