Lights gently Flicker at Idle

[Benz280]

Have noticed that at Idle and running lights may gently flicker, not completely on and off. Can hear a slight a slight draw on the engine when this occurs.
Just curious if this is a sign of something bigger .   

[OZTURK71]

I think it's a charger (Alternator) related problem.

[Kevkeller]

Could be the rectifier diodes in the alternator.

[Charles 230SL]

Could be the rectifier diodes in the alternator.

yes, Kev is right. I had a bad diode in my old 35a alternator. Before the diode died completely (and my red alternator light illuminated), my lights would dim a tad at idle and flicker brighter when I increased RPMs. I rebuilt my alternator and went ahead and replaced the external regulator while I was at it. 

You can buy a new or rebuilt alternator for a fairly reasonable price.

[georgem]

Just to depress you a tad, perhaps at my expense - I had the opposite problem - the alternator light wouldn`t come on at all. A the same time the battery "failed" . So first port of call was the battery place - yes mate, your battery is dead - ....new battery..... no change to the light. Next the auto electrician - yes mate your alternator is toast - reconditioned the alternator and put in a new regulator (and yes, they aren`t too expensive)   Ah, that should fix it  NO.....hmmmm whats left ........... the alternator dash bulb of course - sure enough after going through the convolutions of getting the central instrumental cluster out - yup the bulb was blown. Now I wake up at night thinking that if I had bitten the bullet and started from the other end of the chain all would have been good for a $1 bulb

[Cees Klumper]

If it makes you feel any better George - given your battery had died, there must have been a real problem with either the alternator or the battery, in addition to the light having failed.
Generally I tell myself that if I replace a part with a new one in search of a problem, that turns out not to be the cause, then at least that part will be good for many years. AKA as 'throwimg parts at it' ...

[Benz280]

Thanks everyone, although I did not see the fan belt as lose, I tightened it up a bit and problem resolved.
I am thinking of replacing the alternator given that its original, nothing ever goes bad at the right time .   

[georgem]

Thanks Cees - not sure that is going to stop me waking up in the middle of the night though.............