Re: 1937 120C Current Draw

Posted by humanpotatohybrid On 2023/12/23 21:37:06

That's a fairly interesting arrangement to have a third brush AND voltage regulator. The third brush generators were often just used with a cutout relay, relying on the brush arrangement for the voltage control. In reality, the battery was very important for sinking excess voltage; however, this would also prematurely wear the battery. (In other words, this whole system wasn't very good at its job.) On the other hand, for most cars with voltage regulators, the regulator will control the entire field windings circuit. This one is like half-and-half.

EDIT: I misunderstood the diagram. The third brush powers the one field coil which connects to the other field coil which grounds through the regulator. So the regulator adjusts both field coils, limited to the amount of voltage off the third brush. When I first looked at this I thought one coil was powered with the brush and the other powered by the regulator (both coils grounded).

Bob I highly suspect the cutout relay is somehow stuck closed. If so, the generator will try to act as a motor and will draw current through both the field windings and armature windings. I would be curious to know the cause, if this is not it.