hey guys, well heres my problem. My car has some idling issues, not really in the day time, but at night. When im idling at a red light with my headlights on, the car will bog and ill watch the volts on the meter go down. I have to rev it up a little to get the volts back up to around 14 volts and then it will idle fine. I than tested it by turning my headlights off at night while i was sitting at a light and it idled fine.
Would this be the alternator? There is a slight drone coming from it and i just wanted to make sure by asking, please help me out guys.

 

That sounds plausible. Do you have any non-factory drains on the alt? Electric fan, big speakers, etc.

Edit *s4/s5?*

 

well i remounted my battery to the bin in the hatch, and had a relay made for it.
Its an s5 turbo motor with the s4 non turbo wiring harness

 

bump?

 

i'm gonna say its probably your alternator unless as previously posted you have something extra draining it