turning on headlights makes idle rough

[OhDearAudrey]

Recently i have noticed an issue with my idle. when i turn the headlights on it gets very rough. The in dash voltmeter reads a little over 12 without them on, and goes to 12 when on. Two days ago i noticed the voltage was getting lower and lower as i was driving down the road until the car died. I replaced the battery and the alternator and the voltage still seems low. Is there a component i am missing?

The only thing that has changed since i noticed the issue was i removed the cars after market cd player which no longer worked.

[LeonV]

Your charging circuit isn't charging. Blindly replacing parts in an attempt to solve the problem is not recommended. There is a complete testing and troubleshooting procedure in the FSM. You have not even stated what car this is happening to...