Polo SE 75bhp 1.4L 2006 - Battery light flickering

[Bunsen]

Hi everyone, new to the Polo club and wondered if someone could help.

Twice now my Polo has had the battery light flicker 2-3 times very quickly and then disappearing whilst driving on the motorway. Unfortunately I haven't got the tools to check the alternator or belt tensioner but the serpentine belt looks fine to me (see pictures).





Has anyone had this problem before? Any advice would be greatly appreciated.

Thanks, Dylan.

[RUM4MO]

That belt looks good enough, so, how many miles has that car run as this could be worn slip ring brushes or sticking slip ring brushes, just a couple of other things to check, does the charge warning light come on when the ignition is first switched on, and go off when the engine has started? Next thing to check would be the voltage across the battery when the engine is at roughly 3K RPM with the headlights and heated rear window switched on.
Other than a sticking/worn slip ring brush, it could be a failing rectifier diode.

Edit:- obviously check all the earthing heavy wires and the alternator heavy output lead and battery main fuses as well as the small connector to the alternator.

[Bunsen]

Excuse my ignorance but are the slip ring bushes part of the alternator? As for miles, the car has clocked 34629. Also, all the warnling lights that come on with the ignition, go off when the engine is started. I bought a new battery 4 months ago so hopefully that should be fine.

[RUM4MO]

Yes, the slip ring is mounted on the "inboard" end of the alternator and so are the brushes which tend to be part of the built in regulator.
If changing the electrical loading on the alternator does not make this occur more frequently or change the flicker to a solid "warning light on", then maybe it is a bad rectifier diode or its soldering or associated wiring.
The simplest and quickest fix could be to replace that alternator for a reconditioned one - unless you are able to carry out more investigative testing then remove and open up the inner end of that alternator.