Polarization question.

[Fritz Maurer]

Why does a system not need to be polarized every time the battery is disconnected?

How to tell the difference between A-ciruit and B-circuit generators when they are side by side and not connected to anything?

 

[wore out]

Why does a system not need to be polarized every time the battery is disconnected?

How to tell the difference between A-ciruit and B-circuit generators when they are side by side and not connected to anything?

Every time the engine is shut down the points in the cutout or cutout section of the voltage regulator open, COMPLETELY disconnecting the battery and generator so disconnecting a battery cable(s) at this point has no effect on the generator whatsoever nor does connecting the battery back up so long as the polarity is correct (and even that error doesn't affect anything 'til the engine is started and the generator begins to charge).

An "A circuit" generator will have one end of the field coils connected to the "F" terminal and the other to the "A terminal" or the ungrounded brush or the "third brush".
A "B circuit" generator will have one end of the field windings connected to the "F" terminal and the other is grounded to the frame/chassis of the generator.

 

[John B.]

Why doesn't it need to be polarized every time you disconnect the battery??
There is such a thing called "Residual Magnetism".
When you magnetize a screwdriver it stays magnetized (residual magnetism).

This is what excites the electrons when the generator spins fast enough and starts the electricity flowing. This is why you don't have to polarize the generator each time the battery is disconnected. Now though the battery circuit is opened/disconnected from the generator each time you turn the engine off anyway with the battery cables still connected. If it didn't disconnect, your battery would be drained dead by the next morning. The cut-out relay or (reverse-current relay) does this job. It's been called two different names thru the years, but it does the same job.

This scenario you're asking is no different than a standby AC generator for your house or shop that doesn't have a battery in the output circuit. Residual magnetism is what excites them to start generating.

You can find many small portable AC generators on FB Market place cheap because they run but won't generate (they've lost their residual magnetism for some reason). With them all you have to do is start the engine then plug in a 110v Drill, pull the trigger on the drill and spin the chuck by hand. There will be enough residual magnetism in the drill motor to excite the generator, and the generator will start generating electricity again. I've done this many times. Some people us a 9-volt battery on a cord then plug it into the outlet of the generator but you have to be fast and unplug it quick because the battery can blow up in your hand unless you have a long enough cord between the generator and 9 volt battery so the battery can be a distance from causing any injury to anything or anyone.