Regardless of field magnetism, a stator's internal resistance limits its maximum output. Maybe some of the recent design alternators are cutting the safety margin too close, but the ones I worked on, particularly the big diesel rig alternators, had plenty of over-engineering. As the weight went down, along with the amp capacity going up, I'm sure today's units are working a lot closer to the breaking point than they used to! An old 75-100 amp 10-SI alternator was pretty close to bulletproof unless a battery cell got shorted and put it into full output 100% of the time! Voltage spikes caused by disconnecting a battery cable to "test" the alternator used to fry regulators pretty regularly, though!
Jerry

Last edited by Hotrod Lincoln; 08/28/2010 11:48 PM.
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