[Rob Doe]

Traveler, I'm having trouble identifying exactly where you are in a logical process of elimination. Here are some specific questions that will help me and others home in:

There are normally two or more wires connected at the alternator. One from the terminal box and one or more spliced together that lead to multiple accessories, mainly the lights and horn, etc.

To initially test for problem location (continually charging at 20 amps), leave the accessories wire / wires off the alternator and have only the wire to the terminal box on the alternator.

If the fuse or breaker does not pop when you're wired this way, start the engine and run it. If it pops quickly, before starting the car, report back to us.

You've said that the engine runs pegged at first, then after some time, it settles back to 20 amps and continues to run indefinitely, as in you could drive the car, but then pops when revved to do so? Yes or No?

If the answer is Yes, either the ammeter is faulty or there is a high resistance somewhere in the charging circuit. This could be one or a combination of multiple issues collectively:

This could be a weak battery, too small sized cables, loose, dirty, broken wire strands hidden by the wire's shielding, or corroded connections anywhere in the charging circuit (ground or load side). The battery is the load.

The process of isolating these fault/s is called voltage drop testing. DC Voltage drop testing cannot be done with an ohmmeter. Voltage testing requires that current must be flowing in the circuit being tested etc.

Waiting for Traveler's reply. Sorry for the rehash Jim, Rotor, and others, it took me a long time to think through my post and get it typed in and edited.