Every year i seem to have some kind of electrical problem. This year it is the charging system. Yeah!! I have a 1973 Challenger with a 440. Battery,alternator,voltage regulator and ballast resistor all just a few years old. I was out for a ride and when i came home the car would not restart. I have my volt meter and a cup of coffee. I`m charging up the battery now where should i start? Thanks !!

Have you pulled the bulkhead connectors off and ensured that they are not corroded or melted? Does the car have an ammeter? I'm not super familiar with post-70 cars.

You can also check the yellow wire on the starter relay. It should get 12V when you turn the key to start. Does your car have a 4-prong or 2-prong ballast resistor?

I am assuming that you are charging the battery because it was dead? What did the meter read when connected to the battery?

I just came in from the garage. The battery showed 12.9 v after it was charged.I started it up and it droped to 12.0v at the battery.As i reved it up voltage would go up. As soon as i would let off the gas voltage would drop to 12.0 and into the 11`s. I thought it was the alt or voltage regulator but because of the voltage increase when reving is it a bad battery ?? It does have a 4 prong ballast resistor. The battery is a optima red top about 3 years old. What other should i do?

Well it's definitely not charging. What does the meter read when you hook it to the large stud on the back of the alternator? What does the wiring look like in that area, especially the largest wire?

With the car off the battery reads 11.7 v. With the car running the voltage on the alt stud is 11.7 volts.

I would take the alternator in and have it tested. If it tests good then either one of the field wires is open, the voltage regulator is not seeing a source (12V), or the voltage regulator has failed. Even if the alternator is new don't hesitate to test it. I have had several faulty units in the last few years!

I agree start with the alt.

the fact that it will charge if you rev the motor points to this more than any other part.

a bad vr or not enough voltage to it, does not cause an intermittent charging condition. it usually is bad all the time.

The alternator was bad. I had an extra voltage regulator and i put that on. It still was not charging. I put on a new alternator and it is working great. I have been through 3 alternators in the last 10 years.i`m not sure why my car eats alternators. All is good for now. Thanks for the help !!

Any time. I have also been through several alternators, so you are not alone. Cheap diodes don't last long I guess.