Those "looks like a generator" alternators are usually minimally effective since they violate the physics of what an alternator is supposed to do. Alternator stators and rotors need to be fairly short, large diameter, and the rotor needs to spin at high speed. That's why real alternators have small pulleys and they spin at about 3 times crankshaft speed so the battery gets charged at engine idle. The "faux generator" alternators are OK for "show and shine" car show vehicles that spend most of their time on a trailer- - - - -not so much for ones that get driven regularly.
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!