This is a problem that has slowly been getting worse since spring when i started driving my car. At idle the voltage drops extrememly low, the headlights dim, wipers run slowly, etc. I haven't actually had the car die yet but im sure i could make it die by turning the brights on.

So I had the battery and alternator tested and they checked out okay, the battery has sufficient cca and the alternator belt is good and tight, I visually inspected all the ground wires I could see and they all appear to be solidly connected. So im not sure where that leaves me, car is carbuerated anything i missed or should still check?

 

Just because the alternators good dosnt mean your charging system as a whole is good. I would start by starting the car and measuring the battery voltage. it should be around 14 if now we will have to look into that possibility deeper.

 

at idle the voltage usually reads about 12-13 but thats without anything turned on, if i turn the headlights or radio on it drops so low the headlights nearly dim to off. I can check the voltage at the battery but it'll have to wait until morning

 

When you say it reads 12-13 according to the gauge or a actual volt meter? You have to do this test with a real meter as the stock gauge is not accurate enough for this. Theoretically battery voltage with the car off should read like 12V but then should jump to around 14V when running if it does not increase like that the charging system has failed. Also i forgot to ask what RPM is it idling at roughly?

 

the stock guage is reading 12-13, I'll use a volt meter to get a more accurate reading in the morning. The car idles at about 900-1000rpm while in gear (at a red light) and about 1100 when in park.