No.
It retains polarization via the iron plates, which form weak permanent magnets. It is these plates which are charged with that magnetic field when the locked armature is energized. That sets the North/South polarity of the plates, which is what makes the electrical polarity when the generator is turning.
Now, what can happen is those plates lose their magnetic field over time from exposure to the Earth's own mag field. Like when a generator sits on a shelf for years.
The reason for the plates is so the thing generates a low current when first started spinning. That feeds back into the field coils via the regulator relay and so the thing is self-exciting. You don't need a battery to make it work, as it would do so on it's own. This came from earlier times when engines used hand starting and magnetos yet they wanted electric lights.
Once everyone had electric starters and so always had a battery, then someone thought about how much more efficient an alternator would be. They do need external voltage present to run their field coils because they don't have permanent magnets inside to kick them off.
Oh, and portable power generators have a permanent magnet 12v generator on the shaft with the big AC alternator. The generator self-excites and then powers the alternator field coils so you do not have to have a battery with it.
Stan
