jplante4 wrote:
Ozlander wrote:
Actually, no battery is required on a running alternator, as long as it has a load on it.
How does the field get energized??? :h
It stays energized by the power generated by the alternator. It is often necessary to have some external excitation when starting the alternator from cold, but not to keep it generating once started. (It might also happen, at least sometimes, that there's sufficient residual magnetism to start generating without a battery, but that's not at all a certainty with modern alternators.)
I used to have an old car with a loose battery terminal clamp that would occasionally bounce out of connection while driving. The alternator would keep everything running more or less properly until the engine was shut off. When idling, the voltage in the system would drop noticeably, though--the wipers would slow down, the lights dim, the heater fan die out somewhat...but it would keep running and working until the engine was shut off, at which point everything went eerily dead, at least until the battery connection was reseated. (The bolt on the terminal clamp had stripped out. I was a poor college student and didn't care to spend the money for a replacement connector.)
