[curtis73]

The old way to test it was to remove the postive cable, but it wouldn't really test anything and it would almost certainly fry the diodes in the voltage regulator. The vehicle's ignition system only requires about 15 amps, so the only thing that would tell you is that the alternator is capable of producing about 15% of its original output.

The most ghetto way I can think of is to test the battery voltage with the car running and the car off. Often times a bad alternator will only put out about 11v, so the battery will read higher with the car off. It should be 12-12.7v off and 13.5-14.4v while running. If the alternator is bad sometimes it tests 11-12.5 running. Not always conclusive, but usually linked