Working on a restoration project here. No, it is NOT worth the time or money as a "Generator" but it is worth it to learn how it's done, seeing as I'm a technical instructor now and it's a minor part of the curriculum.
1920's design, six-pole, exciter-cranked generator. The exciter DC windings on the rotor are also the DC starter windings. It's inefficient, sure but it's how the thing was built. The reason for the rewinding is that the last guy decided to ignore the "32V starting" rating on the data plate, and tried to crank it with a common 12V car battery. Burned the exciter/starter coils right up, never did succeed in getting the engine cranked...
Currently, the exciter windings are two turns of 13AWG per coil, wave wound, 73 coils. (73 commutator bars and 37 slots.) The generator is compound wound, so it's electromechanically regulated with a single relay, and in normal operation is very well regulated over it's allowable loading.
I would like to convert the 32V starting system to a 24 or 36 volt system. The manufacturer originally had 12V, 24V, 32V and 48V starting variants, and I know the 12V units had a completely different rotor assembly, with a different number of slots. 12V units had single turn bar-type windings, instead of coils.
The AC rotor coils are concentrically wound on the rotor stack first, then the DC exciter/starter coils are wave-wound over the top of them, in the same slots. There are 26 turns of 11AWG per each of the six AC coils.
The Stator assembly consists of 6 poles/coils with 300 turns of 14AWG and 15 turns of 10AWG wire per pole. All coils are wound in series, and the diagram seems to show the stator coils in series with the DC brushes. Not 100% sure, the wiring diagram is a bit difficult to follow yet. I'll work on getting it cleaned up enough to post here.
Given that the rotor assembly has 2 complete turns per each coil at 32V, I can't just ratio my way to a 24V starting coil on the armature. There's probably going to have to be some stator coil adjustment as well...can't very well have 1.75 turns of wire without some creative commutator work...
I've ordered a few books and done some reading up on the subject, and I've rewound motors before-this is the first time doing one of these double-duty DC Exciter/Starter systems though.
How should I approach the voltage conversion here?