For instance, the charging system tester/battery load tester I use in my shop has a 600 amp DC capacity! It uses an inductive current probe. The high range is used for load testing batteries. An average alternator from the 70's and 80's that's the most popular conversion for the old stovebolts will be anywhere from 55 amps to 80 amps at full output. One with a bad diode will usually have a max output of 15 amps or so, enough to keep the battery charged during daytime running, but not sufficient to carry headlights, heater, etc. without draining the battery. An alternator with a shorted diode will be noisy, and might be hotter to the touch than normal.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!