New guy with a Zenith Wincharger model 38

[bobwilson1977]

Hi all. About a week or so ago I acquired a Zenith Wincharger. It came with the original blade, the generator and tail fin. I had to fabricate a stand for it. I will freely admit this is not in my wheel house. So I am seeking some very basic advice. As it sits now if I put it all together and let it rip- and since I live near a beach and there is usually wind it is spinning pretty fast, I am getting a total of 2 volts out of it. Barely enough to dimly light a 6 volt light bulb I have attached as a load. I have cleaned the armature, cleaned the gaps between the copper sections, cleaned and inspected the brushes, confirmed that all of the field windings have continuity and tried adjusting the 3rd brush. None of that makes any difference.

I am an antique radio guy and was on my radio forum and one of the users said I had a few things going on. One was that he thought the field coil windings needed to be re-polarized. He sent me a link to a video showing how to re-flash generators. If I am understanding this correctly, does that mean briefly touching the F terminal and ground with a 6 volt battery source? I wasn't sure.

The other thing he mentioned was that this won't generate the proper voltage without a battery because since this doesn't have permanent magnets the field coils need excitement from an external source ( battery ). I also realize I will need some sort of regulator. I have on order a 6 volt cutout relay as well as a ammeter for that purpose.

ANY advice would be greatly appreciated.

[Wind Charger Mike]

The 2V you are measuring is likely from the residual magnetic field in the iron. These generators are self excited and use the residual field to initiate the field excitation. The armature output is “shunted” through the field windings to ratchet up the field current. So the residual field is probably fine and you don’t need a battery to make voltage. Have you checked the field coils for continuity? I suspect you have an open circuit or short in the field coils. A 6V generator can make over 20v open circuit easily in a good wind. A dirty commutator could also be the culprit.

[bobwilson1977]

Thanks for the response. I did check for continuity and unless I was measuring the wrong things they seemed to be ok. What I did was measure both of the leads going to the two lower brushes from those to ground and I was getting continuity. Silly question: Is the commutator the area that the brushes engage with? If so it was filthy when I first got it. I cleaned that up and also took a knife blade to clean the gunk out from the gaps between the sections. They were packed with old grease.

[Wind Charger Mike]

Yes, the copper commutator bars are what the brushes ride on and chop up the ac output of the armature into dc. If the surface is dirty or oxidized, the armature voltage generated by the residual magnetism may not be sufficient to overcome the surface impedance.
Do you know what the prop speed is? 300-400 rpm is the range needed for 6V.

[bobwilson1977]

Thanks. I will take another look at the commutator. Also- do you know if new brushes can be found for these? The old ones are made by AC Delco which makes me think they were common brushes for automotive generators. I am not certain of the RPM. I live on the coast and when I tested it out it was definitely spinning rather fast.

[Wind Charger Mike]

You can bench test it by rigging up a hand drill to the nut on the generator hub. You’ll feel the increased torque once it starts self exciting.

[Wind Charger Mike]

I’ve not found a source for the exact brushes but I haven’t looked that hard either. I’ll modify something close or rob from another generator.

[bobwilson1977]

So here is an update. I got this to work. But what I find is that it takes a considerable amount of wind to get it to generate power. I live near the coast and there is often a 10-15MPH breeze. The windmill seems to need to spin rather fast and this translates to maybe around 20% of the time where its creating electrical power. Does that sound normal? Were these meant more for people who lived in fairly windy areas?

I did find that brushes for Ford Model A's will fit this so I have new ones on order. So that might improve performance.

[Wind Charger Mike]

I attached a plot of 6V Wincharger model 39 wind tunnel test results that was performed by U of Michigan in 1938. If your prop and gen are original and unaltered you should reach 6v with a 8mph wind…as indicated on plot. You can see the air brake starts to kick in around 20mph and the output curve rolls over.

[bobwilson1977]

Greatly appreciated. Seeing this makes me think mine isn't putting out enough juice. So far I have done the following: confirmed the fields are good. Reflashed the coils, they have good strong magnetism. Checked all of the leads on the armature and commutator. Cleaned all commutator sections and spaces between. Adjusted the 3rd brush to max output. So it "should" work. The only remaining thing are the brushes. One person who was observing me the work on this the other day thought the brushes looked pretty worn out. So it could be there is not enough spring pressure to hold them firmly against the commutator. I'll try those. But if that doesn't work then I'm not sure what else could be happening here. These are super basic things so there's not much to go wrong.