Originally Posted by hellosailor
Must be a translation problem. One doesn't "polarize" an alternator. An alternator has no inherent polarity until the regulator gets added into the wiring, and then the polarity is fixed and permanent, based on the construction of the regulator. There's no way a mechanic can change that, or "re-polarize" or "un-polarize" it.
I'm guessing a VP2030 is a Volvo Penta engine, but that doesn't tell us what kind of alternator they bolted onto it, or what kind of regulator is being used.
my initial thought was the same as yours. But it seems to me years ago I ran into a situation in which the soft iron core became magnetized by high voltage spike so that it was canceling part of the electromagnetic force resulting in an alternator that seemed fine but had low output. the fix was to demagnetize the cores. maybe that's what he meant by polarizing/?