Dual generator setup on '75 Whitby 42

In the process of buying a '75 Whitby 42. It has two generators mounted on the FL. One seems much bigger than a normal generator and is driven by twin belts off a bigger than normal crank pulley. Owner was no help "charge the batteries". Does the small one charge the start battery and the big one the house bank? Looked at a '85 with the same setup except that the pulley for the big generator seemed to be home made.

Thanks,

Bob

Are these actually alternators attached to the engine?

1. Where do the wires go?
2. Can you post a picture?

The backup alternator is a thing. In some cases both charge both banks though diodes.

Sorry, should have said alternators. They are attached to the engine. The bigger one is driven by a dual belt pulley off the crankshaft. That crank pulley is larger than the normal crank pulley. No pictures, boat is in FL and we are in TX. Owner has no clue, says they charge the batteries, but which ones?

If the boat has refrigeration, many boats had separate alternators installed to run the compressors. Grunert was a major supplier of these types of systems. Depending on the system, they were designed to run on either 12v or 24v. I think the larger systems (separate large refrig and freezer compartments) had 24v alternators. The 12v or 24 volts produced by the alternator is converted to 110/120V DC to run the DC motor that powers the compressor. Some of the 12v alternators were setup to also be a backup to the charge batteries,as well.

The boat does have refrigerator and separate freezer, NovaCool(?). I thought that maybe this is a common setup since the two Whitbys we looked at both had the dual setup.

Still waiting on seatrial and paperwork. I guess I'll trace it out when we actually own the boat and bring her back to TX.

Bob

Attached are the pictures of the alternator and the regulator. There are no markings on the alternator or the regulator. Have not yet been able to trace the wiring.

Bob