Generator not charging, 1929 Hupmobile 8 cylinder FIXED!!

[dalef62]

I have a 1929 Hupmobile 2 brush generator(correction it is a 3 brush generator)that refuses to charge.  I have checked the fuses and the brushes look good.  It was charging good a year ago and then when I went to get it out last year it was not charging.  

I put a test light on the cutout on the battery side and I have power.  I also replaced the cutout last year thinking it was the cutout, but no change.  I took the cover off the cutout and closed the points and no change.  Everything looks in order as far as the brushes, armature, wiring, etc.  How can I test the generator on the car?

Do I need to flash the generator, if so how on a two brush generator?  

Edited September 16 by dalef62 (see edit history)

[Bloo]

This is a 2-brush generator with only a cutout? If so, I don't understand what keeps it from burning up. What is the field terminal connected to? I think we are going to need to see a wiring diagram or something.

 

Flashing is or can be necessary on just about any generator. If this were a normal third brush system with a cutout, closing the cutout points should have flashed it.

 

 

[dalef62]

11 minutes ago, Bloo said:

This is a 2-brush generator with only a cutout? If so, I don't understand what keeps it from burning up. What is the field terminal connected to? I think we are going to need to see a wiring diagram or something.

 

Flashing is or can be necessary on just about any generator. If this were a normal third brush system with a cutout, closing the cutout points should have flashed it.

 

 

I am pretty sure there is only 2 brushes.  It has run like the for as long as I remember, 1970?  It never did get run very much though.  If it only has 2 brushes, what kind of setup should it have?  

I will look to see if I have a wiring diagram.

Thanks!

[Bloo]

A 2-brush generator needs 3 things, current regulation, voltage regulation, and a cutout. Usually it's 3 relays in a box. It also needs a second wire/post coming out of the generator so the voltage regulator and current regulator can control charging rate via the field coils.

 

Some 3-brush generators have a second wire too. This is for a voltage regulator as seen on mid 30s Buick, Pontiac, Chrysler products, and some others. A system like this would typically have 2 relays in a box, cutout and voltage regulator. Current regulation is still by third brush. Hupmobile did this for about a year around 1914 or 1915, but I would really not expect it in 1929.

 

Finally a "third brush and a cutout" system was very popular in the late 20s and early 30s. This is by far the most common thing to see on a 1929-ish American car. There is only a cutout (one relay). Current is regulated by the third brush. There is no voltage regulation at all. It is not ideal. Some makes have kludges like thermal switches to make it a little better. There is only one post on the generator, and it connects to the cutout.

 

A peculiarity of a third brush generator is that if it is run with no battery connected the field windings will burn up. Some makes have a fuse. Is this a Delco generator? Those may have a little resistor inside that sometimes burns up in a valiant attempt to protect the field windings.

 

When you figure out what you have I (or others here) can probably tell you what to do next. If you can't find a diagram, some pictures might help. Good luck.

 

Edited May 8 by Bloo (see edit history)

[dalef62]

I believe I read it has a Autolite generator and I did see a wiring diagram and it on had one wire coming out of it, as does my generator.  I will try and get conformation on that information as soon as I can.

Thanks for your help Bloo

[Oldtech]

I am betting that it is a regular 3rd brush generator.  My old Auto lite manual has no 2 brush one wire combo. 

[dalef62]

Ok, it helps to have a little light on the subject.  It is a 3 brush generator with a cutout.  It is an Autolite.  And yes the fuse is a piece of aluminum rod and it has continuity.  Dad worked at Alcoa.   😂 

Edited May 11 by dalef62 (see edit history)

[ArticiferTom]

Hope not having fuse took out field coils .

[dalef62]

13 minutes ago, ArticiferTom said:

Hope not having fuse took out field coils .

That fuse has been there forever...

[bob staehle]

If the bare wire on the gen terminal is touching the mounting screw, no charge

[Bloo]

There is probably damage. I hope not, but if the cutout didn't pull in, and it ran, it definitely tried to burn out the field coils. Maybe you got lucky. I hope so.

 

On a third brush system, the third brush is partway between one brush that is at battery voltage, maybe 6 or 8 or a little more as it is unregulated, and the other brush that is grounded. As such the field runs on part of the available voltage. Lets say 80 percent to pull a number out of the air. If the battery is at 8 volts, the field is at 6.4 volts. The more the battery voltage rises, the more the field voltage rises. The battery voltage moves slowly as it charges and battery is the only thing keeping the voltage under control.

 

If a battery cable falls off, or a cutout fails to pull in or something like that, the generator voltage just runs away with no battery to hold it back (voltage is unreguated). So if it gets to 40 volts, or more, the field that was meant to run on about 6.4 volts (or so) is now running on 80 percent of 40 volts (or maybe more). That lets the smoke out pretty quickly.

 

I think you'll probably have to take it off of there and have a look inside. It doesn't look easy to get off, does it? To test further on the car we would have to figure out how it is wired internally and see if the field could be disconnected somehow at both ends without taking the generator off. I kind of doubt it. If you could, you would want to check the field for ohms (and compare to some book that has specs for your generator), and to make sure there is no continuity to ground.

 

Note that one end would be connected to ground (or possibly hot) in normal operation. It would need to be disconnected for any testing.

 

Edited May 11 by Bloo (see edit history)

[Fordy]

It's toasted. Pull and get it repaired - there is no shortcut in this situation. To "motor" test it, it needs to come out anyway so may as well go the whole distance - And loose that slug of Al which caused the issue in the first place and replace with the correct fuse,

Steve

Edited May 11 by Fordy
typo (see edit history)

[37_Roadmaster_C]

You have easy access to a very basic test. Remove the "fuse". now one end of the field coils are isolated. Next check for continuity from the fuse clip to ground. If there is none, you have an open coil. Do this test with the battery disconnected!

[dalef62]

On 5/12/2024 at 11:18 PM, 37_Roadmaster_C said:

You have easy access to a very basic test. Remove the "fuse". now one end of the field coils are isolated. Next check for continuity from the fuse clip to ground. If there is none, you have an open coil. Do this test with the battery disconnected!

I tested the field coils and they are not open.  Tested with an ohm meter.

[Bloo]

Which way are they connected? One end to the third brush and the other end grounded? Or one end to the third brush and the other to the output post?

 

There's really not anything to keep it from charging, well except a bad armature, but even then I would bet on it doing SOMETHING. Did it throw solder?

 

It just about has to be brushes not making connection, or something not connected inside. On the main brushes, one is grounded and the other goes to the output post. The field connects between the third brush (at one end) and either ground or hot (at the other end), whichever main brush (hot or ground) is furthest from the third brush.

 

[Fordy]

Resistance of the coils? internal short could be the culprit - if under 3 ohms then that's not good.

[dalef62]

Ok, I got back to the Hupmobile today.  The Aluminum slug is out, battery is out and I was checking things with an ohm meter. 

 

First thing I tested was the fuse holder, I have continuity through the fuse holder?  It should be open, the fuse is not there...

 

Next fuse holder to ground, continuity...

 

Next generator post on cut out to ground, continuity.

 

Next armature commutators to ground, continuity. 

 

Everything I touched in the generator went to ground!  

I see no lead thrown around, nothing smell burnt, nothing looks burnt...

I started to take the generator off and need assistance, how do I keep the timing chain where it should be?  I have the shaft off from generator to water pump/distributor.  I was going to take the rear brush plate off but I couldn't get the shaft connector off the back of generator.

Help...

[dalef62]

[Fordy]

Pull the brushes and take the readings again as that is where the readings to ground may be coming from. All the internal resistance is so low it will read a short on most meters and with the brushes in you do have a path to ground as it is still a complete circuit. The armature if it shows no shorts to ground off the commutator bars may still have internal shorts between windings which will only show up with a "growler" test. The third bush to ground will give you the field windings. One of the main brushes will be grounded and the other not - this should be the only grounded brush holder. Make sure the leads to the fields and brush holders are not contacting anything.

Good luck

Steve

[dalef62]

Ok, I finally got around to removing the generator from the hupmobile.  It is now laying on the floor.

What are some of the easy test I can do to figure this thing out.  How do you motor a 3 brush generator?  Test for bad fields?  Test for bad windings?  Where should I start????

 

[Bloo]

2 hours ago, dalef62 said:

How do you motor a 3 brush generator?

Good question. I never seem to get around to that test. You only have one wire coming out, right? You probably just use jumper cables or something and connect your 6v battery to the case and that wire. Use the polarity of the car (in other words positive to the case if it's a positive ground car). Actually I would wait and see what the others say about this before trying it.

 

2 hours ago, dalef62 said:

Test for bad fields?  Test for bad windings? 

To test for a bad field, you have to disconnect both ends of it. You might or might not be able to do this without taking the generator apart. Probably it has to be apart. One end of the field is connected to the third brush normally. That is the brush that is out of line with the other two. The other end is connected to either 1) ground or 2) the "hot" main brush and the wire coming out.

 

With the field (stationary windings) disconnected, get a 12v car battery, a clipcord, and a 12V test light, one of the old style ones with an actual incandescent bulb in it. Connect one battery post to one end of the winding. Connect the other battery post to the test light. Probe the second end of the winding with the light. Should light. Did it light? Good. Now probe the case. The light should *NOT* light. Polarity doesn't matter, just don't forget to polarize the generator when it is back on the car. If it passes this test, call it good for now.

 

battery post >> wire >> one end of field    (and)   other end of field >> test light with bulb >> other battery post   lights

 

battery post >> wire >> one end of field    (and)   generator housing >> test light with bulb >> other battery post   does not light

 

DIsclaimer: You are checking for leakage or shorts to ground. A real auto electric tech who rebuilds starters and generators would use more voltage than a car battery can provide. This test is sort of bogus, but is a quick thing you can do when you don't have professional equipment handy. I did it that way for decades and I don't recall ever being wrong. Your mileage may vary.

 

And then there is the armature, which can be sort of tested if it is out of the generator. The best you can really do is the second test like above. Also inspect to see that no commutator segments have become unsoldered due to overheating.

 

battery post >> wire >> armature shaft    (and)   each and every single commutator segment >> test light with bulb >> other battery post   should not light

 

There is a potential gotcha.  The test above only checks for shorts to ground. A pro would also use a "growler" to check for shorts between windings. It is possible a bad armature could still "pass" if there were a short between windings.

 

Other stuff:

 

Sand/polish that black stuff off the commutator, preferably not with emery. You might need to have that machined, but I don't think I would have it machined unless you are changing the brushes, and I would not change them unless they are fairly used up. You only get so many machinings, and the generator would have to break in all over again. On the other hand, if the brushes are worn out, machine the armature and start fresh. 

 

Generators (but not starters) need their commutators undercut. Check to see that the "mica" or whatever it is between the commutator segments is at a lower level than the copper segments. Fine if so. If the "mica" is up level with the copper, you will have to scrape some out from between the segments. A broken hacksaw blade works for some generators, but on others the gap between segments is too narrow. That should give you an idea what kind of tool you need.

 

Check your bearings (and or bushings) for wear and replace if necessary. There are probably felt oil wicks. If so, they are the sort of wool felt used in machine tools. They're not going to be photogenic, but make sure they can absorb oil. If not, and no new felt is available, sometimes you can soak them in MEK and poke at them. They often come clean enough to carry oil. You may need to make gaskets tor the oil cavities.

 

Edited September 10 by Bloo (see edit history)

[Oldtech]

What Bloo Says. By the look of the commutator in the picture I would turn it.  If the brushes are still good just take a bit of fine emery and wrap it around the commutator with the brushes in place and turn it to smooth off the brushes. They don't have to be perfect. 

[dalef62]

Had the generator all apart today, cleaned things up and did some testing and everything seems to be in order.  I want to hook it up in a test stand and see if it produces anything.  Might get time tomorrow night.

Thanks for all the help and information, it is very much appreciated!

[dalef62]

Was able to motor the generator last night, negative to single wire, positive to generator case.  That test was good.

Tried to test operation of generator with a electric motor and a belt around the gear but could only get minimal voltage (.25).  Maybe I wasn't doing it right, or the electric motor wasn't turning fast enough.

[Bloo]

It takes quite a bit of speed. 3rd brush generators work by powering the field from that third brush. It's a percentage of the output voltage. If one main brush is at 8 volts for instance, and the other is at ground, the 3rd brush is partway in-between and will be some part of that voltage, according to it's position.

 

Lets say the 3rd brush has 80% of the generator voltage, just pulling numbers out of my... err... hat... for an example to show how it works (not real world numbers for any particular generator).

 

6 volts on the output would be 6 x 0.8 = 4.8V .

7 volts on the output would be 7 x 0.8 = 5.6V .

8 volts on the output would be 8 x 0.8 = 6.4V

 

As you can see, the more it charges, the higher the field voltage gets and the harder it tries to charge. Never run a third brush generator on the engine without the battery connected. The field will probably burn up. The only thing holding the voltage down is the battery. 20 or 30 volts on the output would be 16 or 24 volts on a field designed to run on about 5 or 6 volts (in this example). If you ever have to run one on an engine with no battery, ground the output solidly. 80% of 0V is still 0V and it will never be able to get started charging.

 

Be careful spinning the generator real fast. If you do, be sure you are able to rapidly quit as the voltage will try to run away as illustrated above.

 

My gut feeling is if you tested it and cleaned it up and everything seems to be in order, and it motors, it will probably work now.

 

Your cutout should pull in at whatever voltage the manual says, but it is fairly low. It takes a pretty refined bench power supply to check it for the correct value, but a quick check can be done by just connecting a 6V battery to see if it pulls in.

 

With cutout disconnected from generator, hook one battery post to the cutout terminal that the generator would normally connect to. Hook the other battery terminal to ground. Use the polarity the car uses. The cutout should pull in. If it pulls in, then disconnect it and drag a points file between the points ONCE to make sure the points will conduct. Don't overdo it or try to make the points look new. One scrape is usually good, and then it should work.

 

Edited September 13 by Bloo (see edit history)

[dalef62]

Today I was able to get the generator installed on the Hupmobile and success!  Seems to be in time and the generator is changing again.  Not exactly sure what the actual problem was as I saw nothing glaringly wrong.  I tore it completely apart, cleaned armature, checked brushes, wires, fields, etc.  One thing that may have been the no charge culprit was a bare area on the wire going to the cutout???

Anyhow, it is working properly again and I want to thank Bloo, Oldtech, Fordy and all others that offered tech information and assistance!  I was greatly appreciated.  The knowledge on this forum is outstanding and should be commended!!

Thank You!!

[dalef62]

I will be at Hershey Green field spaces GBC 7-8, stop in and say hello!