I did a little searching, and found an interesting thread about tractor generators. Half way down, there is a long post by a guy named Al.
He knows what he is talking about. The only difference I can see is that golf cart starter/generators run in both directions. But, that is what a DC generator is all about.
I'm going to study up a little more on the shunt coil for charging, and the series coil for generating.
https://simpletractors.com/forums/to...-generator-or/