2001 Synergie noise and flashing battery light when idling

[Taximum]

Hi
I'm hoping someone will be able to give me some advice with this.

2001 diesel HDi
always had funny electrics - brake light bulbs blowing/electric shocks getting out of car in sunshine/temp warning light flashing but no overheat/speedo not working
But...
now there's a noise that I thought might be the fan belt slipping when the car is idling
battery light sometimes flicks on when the noise happens but goes off quickly
noise stops when the car gets going
noise isn't so bad when the air con is switched off
noise is getting worse over time though
garage had it for a day - not the belt but no real idea what's happening

Does anyone have an idea of what's wrong please? I love my car and want to keep it going - but not if it's going to cost a fortune.

Thanks

[DickieG]

Its more than likely the two parts of the bottom pulley are slipping, paint a couple of lines across the two sections joined by the rubber in between them, if the sections are slipping, after running the engine especially with the A/C on the lines will no longer be aligned. A new bottom pulley will be required if this is the case.

[Xantidote]

Could it be the belt tensioner, or an idler pulley, with a bearing going? If the noise is getting worse, then ultimately something will fail, and then it's a matter of how much damage .

Even though it's been pronouced that it's not the belt, I'd still be looking in that general area.

[Taximum]

Thanks both. I think I'll have to take it to a dealer rather than my local garage. I'm not competent to work on the car but at least if I go in sounding as if I know a bit more than zilch, we might get somewhere.
Thanks

[addo]

Ignore the broken bits; what's relevant here is the white stripe about one o'clock on the pulley. It starts on the innermost portion, crosses the rubber ring and continues on to the outer section.

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When a balancer pulley "slips" the inside portion doesn't move at the same rate as the outer portion. The paint line then becomes disjointed and failure is clearly seen.