Starter But No Generator

[TonyAus]

Suggestions required. Today the generator function on my 1925 roadster's starter/generator suddenly went out to lunch. The starter still works fine. I checked to field fuse, which is OK and all the connections are tight. The Mechanic's Instruction Manual and the Book of Information do not provide specific troubleshooting advice on the starter/generator unit and accordingly are not very helpful. My next port of call will probably be the cutout in the starter switch. However, as it is a bit of a pain to pull out I have decided to seek the advice of those knowledgeable on the subject before delving into the depths. Any ideas - this must have happened to someone else in the past?

Thanks in anticipation

Tony

[cahartley]

Tony, that box isn't as hard to remove as you think........I thought the same thing.......

The wires are (or SHOULD be) long enough to pull the box into the car where you can disconnect the wires.

Check the cutout points condition and also power it up on a battery charger to see if, indeed, the cutout is at least switching.

If the wires aren't long enough disconnect them at the other end and replace them.

There's no way in hell anyone could make the connections from the engine side of the floor boards......... :mad:

The wires could probably stand replacing anyway.

Edited December 7, 2013 by cahartley (see edit history)

[TonyAus]

Thanks

Great minds think alike - I have just been down taking a second look at the starter switch and have come to the same conclusion. There should be enough slack in the wires to pull the switch right forward. Actually, I rewired the car when it was reassembled about four years ago so the wiring is as good as new. At that time I made the connections from the engine side so it can be done - just a real pain!

The more I think about it, the more the cutout appears to be a likely culprit - possibly a dirty core contact rather than the cutout points themselves. However, I have been wrong in the past more time than I would like to admit.

Keep the suggestions coming.

[Guest DodgeKCL]

The Reverse Current Cut Out (RCCO) was the most troublesome part of the old electrical systems. If they stuck closed after turning off the key and putting the car away,the battery would drain to zero in time. And sometimes cause a wiring fire in the process. (That's why its' pretty well mandatory to install a batttery disconnect switch.) Because of my background ability,I've pulled out the guts of the cutout in all my vehicles over the years and installed a 50 amp. stud mounted silicon diode to take the place of the relay and points. The average current of these old systems is around 20 amps so the diode is never stressed. I do not get that 'flash' in my headlights and dash lights when the cutout switches the generator off and on the line. Nor can any current flow back into my generator from my battery. The cutout MUST have some current,usually about 3 amps, flowing backwards for some seconds to 'kill' the magnetic pull of the bobbin and have the cutout's spring take over and release the cutout points. Also because of arcing, while trying to connect and disconnect the generator's current, the points fry and go high resistance which just makes things worse. I highly reccomend this update. You cannot tell it's been done because the RCCO cover and mounting is still used. I've had this mod now for 30 years and no failures. The only time my ammeter can show a 'discharge' is when the engine is not running and I turn on a load like the ignition. The moment the engine starts I never again show a discharge. I think this mod,and keeping my batteries constantly charged when not in use, has allowed me to get up to 12 years out a 6 volt battery,10 years on the last one.

Edited December 9, 2013 by DodgeKCL (see edit history)

[2251DB]

I discarded my reverse current cut out for the same reason ,I also use the diode method for current cut out

The dodge generator only has a low output so any diode which has a higher rating is suitable, the larger size will dissipate the generated heat easier

Cled Davies in VICTORIA has ready made units available for these vehicles.

[MikeC5]

Any suggestions on where to obtain the diode in U.S.?

[TonyAus]

Thanks to all. After a 10KM run this morning my charging has been miraculously restored. I can only take it the problem was a stuck cut out which was freed by vibration. The vibration is another problem which I intend to address in the near future. As it is not now broke, I will not fix it. However, as the motor has to come out I will take a hard look at the cut out then when it is more easily accessible.

Mike

I understand that Myers do an exchange starter switch fitted with a diode.

Cheers

Tony

[platt-deutsch]

Hook a DC voltmeter to the Heavy brass terminal on the Starter/Generator and read the voltage to ground.. If its 14 volts or more at a fast idle the generator is putting out. If the ammeter don't show charging then I would suspect the cutout relay.

[Guest DodgeKCL]

This is what they look like. The stud is usually 1/4" 20 thread which is common North American. Very common in surplus stores that sell electronics. But can be purchased new in an electronics trade supply store. Used in high current rectivication like power supplies. If you get one that has a rating over 40 amps. the generator/battery combo in our old cars can't blow it. If you buy new the counter staff will most likely know what you want. If you buy surplus surprisingly you can find most diode/transistor/integrated cct. numbers on line now. (Amazing!) The specs will tell you current carrying ability as one of the major specs in the list. They are all silicon now. No germanium left these days except for signal detection in radio. If you take the time and trouble to do this mod, you will never have RCCO problems again. It is because of diodes that alternators have no cutouts. Current can't flow back through a diode.

[MikeC5]

Thanks very much DodgeKCL. There is a supplier here that offers starter boxes with this update but I'm sure I can do this myself.

[RAH]

Tony, All good responses here but there is one more thing to check. The 'thrid brush'. That is the one that is adjustable on the bottom of the unit. It may be worn down or the spring broken or not enough tension. As suggested here, attach a voltmeter to the main output terminal and compare the voltage with the engine off and then with engine running. It should show an increase. Then reach under and pull the bottom brush loose to see if there is any difference in output voltage with the brush seated or released. Also try adding a bit of finger pressure while running to see if there is any difference in conditions. As was also suggested here a rebuild of the starter switch with diode works well. One caviat, however. The polarity of, and mounting considerations of that diode are critical. Those high current diodes that are stud mounted have either cathode or anode to the stud and in both cases must be isolated from the base mounting plate or ground. Also remember you are dealing with a 'Positive Ground' system. Suffice it to say this is not generally a job for the electrically challanged. Good Luck and Keep 'em Dodgin' Rodger "Dodger"

[MikeC5]

I just did this mod but haven't tested it yet. I used a 70 amp max rms diode with stud as cathode. I used the coil holding bracket as a heat sink (removed the coil/points). I do prefer whenever possible to keep things original but the risk of points sticking and frying the generator is not a risk I care to take. Researching it gave me the impression this failure mode is not that uncommon.

[72caddy]

Dug up this older topic as I seem to be suffering from the no-generation issue and have already had one starter generator mysteriously die completely. I would like to do this conversion but I am definitely 'electrically challenged'. Does anyone have a step by step instruction for how to install the diode into the existing starter box?

My car is a 1919 touring.

TIA

Richard

[MikeC5]

I recently discovered that the generator portion of the S/G isn't working (starter could not crank enough).  I did recently disconnect battery and remove the starter switch (installed new floorboards).  I'm sure it was correctly reinstalled though.  I had also (over a year ago) replaced the points/cut out with a hefty diode, wired for positive ground.  So I don't think the problem is the there.  Could this be a polarity issue as in, I needed to polarize the generator when I put things back together?

 

A few other clues: the starter operates but is rather weak.  It will crank the engine a partial revolution, then stop.  If I release starter switch and then re-apply, it will do the same again.  When car engine is started & warmed up, the ammeter reads a slight discharge (large discharge with headlights on). Voltage measured at battery with car running is no greater than when car is off which tells me no charge is reaching battery.  I am also confused by the voltage reading taken between output terminal on generator and ground; roughly 2 volts.  Does that number even make sense?  I would think it could be no lower than battery voltage and I did have the battery freshly charged, measuring 12.6 volts at terminals....

[cahartley]

First things first.

The starter/gen is self polarizing.

The first time you hit the starter it polarizes automatically.

Check the ground, check the ground and check the ground.

Take a look at the two uppermost brushes as they are the ones that count for starter operation.

The starter COULD have a dead winding, or more, but the fact it always starts to turn again leads me to think not.

Mine was acting the same way until I got PROPER, ie; COPPER bearing brushes, 

I wouldn't fiddle with the third brush yet if it was generating normally until you get the starting function figured out.

[MikeC5]

Thanks CA. I will clean the grounding lug and I did re-tighten the connections on the starter switch already.  Where did you get your brushes?  Mine appear to be OK as far as wear but it isn't obvious what material they are. 

[cahartley]

The brushes should be a dullish gray.

I forgot to mention one thing.

Remove the brush cover strap and try turning the engine again.

CAREFULLY feel for heated brushes.

I got brushes from startergenrebuilder who posted in my thread there >>> http://forums.aaca.org/topic/236403-does-anyone-have-a-servicable-north-east-model-g-startergenerator/

I think Meyers' Early Dodge also has them.

 

After checking your profile I see your Dodge is also a '25.......

Out of curiosity does the head on your engine have primer cups?

Edited July 8, 2015 by cahartley (see edit history)

[MikeC5]

No primer cups Craig but I can't be sure the head is the original either.  I noticed while perusing in Myers starter/generator section that they sell switch box grounding straps.  Apparently the one on my car was lost long ago and I was unaware there was such a critter.  Why does the box need to be grounded?

[cahartley]

I believe it NEEDS to be grounded in order for the solenoid to close to complete the circuit for charging.

 

I asked about the head on yours because it was noted by a member in another thread my '25 shouldn't have primer cups.

Mine is #A131422.

Depending on what model year and the time of year changes were made you never know what happened during transitions....... 

[72caddy]

Interesting thread. I need to see if I have a switch box grounding strap as well. Never heard of it. Love this forum!

[MikeC5]

My car is S/N A323967 so primer cups should not be there I guess.  Does anyone know what resistance you would expect measured across the field windings?  I mean with generator output cable disconnected and then measuring across output terminal and ground stud. 

[cahartley]

Mine is A131422.

Neither the Dodge Brothers bible nor the North East Instruction Bulletin give resistance information so can't help you with this.......

 

As an aside I just noticed, while reading the North East Bulletin, the bottom brush (generator output) is a carbon brush.

Only the top two brushes for starting are copper bearing.

 

Anyway there are a lot of diagnostic things you can try which are outlined in the North East Bulletin.

If you like I can scan the pertinent pages later.

[MikeC5]

Craig, that would be great.  I think I bought a copy of that bulletin from Romar but am not able to locate it.  The other thing I'm wondering is how do you go about replacing the brush springs?  Must the whole unit be pulled apart (remove armature) in order to do this?  My springs are not broken but I was going to go ahead and get new ones for a little piece of mind.

[MikeC5]

Update: I removed the brushes and they looked OK.  Not sure what they're made of but the two main brushes definitely feel heavier than the thinner 3rd brush (so I'm guessing that one is at least carbon).  I cleaned up the commutator a bit with some fine sandpaper, checked the mica, and fingernail test shows it to be below contact surfaces.  Cleaned the ground lug, put it all back together and now it works!  Starter cranks faster and it is charging (and responds to movement of adjusting 3rd brush).  Still, the brush springs are rusty and I'd like to put new ones in.

By the way, with this image from Dykes auto encyclopedia (attached) I was at least able to measure the resistances for the positive and negative main brush circuits and the 3rd brush circuit between the brush connection and the fuse (field circuit).  0.6 ohms for mains and 1.8 ohms for 3rd brush circuit.  Also, the left side (when viewed from driver seat) of fuse holder should have continuity to ground.  While I don't know what the recommended values for these resistances are, the generator was putting out a little over 14v so presumably, they are close to what they should be. 

[cahartley]

YAY....... 

 

Once I started scanning I figured I might as go all the way so IF the nearly 18 meg PDF of the 1925 North East Equipment booklet attaches anyone who wants it can have it......

 

The PDF won't attach so I'll host it.

 

Get it there >>>http://andersonofrosholt.com/mypics/1925_North_East _Equipment.pdf

[MikeC5]

Thanks Craig.  I guess I spoke too soon...  I took it for a ride and as soon as the engine started to warm up it went back to slight discharge when running (without headlights).  With lights on it was on discharge side 6 - 8 amps.  Argggg !

[cahartley]

That COULD be a third brush issue.

The booklet offers some things you can do.

Hope one of them does the trick for you........ 

[MikeC5]

An update on my generator; I installed new brushes and brush springs, sanded the commutator, checked mica, cleaned things up, oiled the rear bearing (which seemed fine).  Put it all back together and...  it does the same thing.  I'm not surprised really since the brushes and springs I replaced didn't really look that bad. I also sprung for a new battery.  So it starts great.

 

I did some more testing with a volt meter on the generator output terminal.  After start from cold the output is up to around 16 V (idle) and over the next few minutes it drops down slowly to around 14.  When I put the lights on it drops to around 13.5 V.  After idling for 15 minutes or so, I blip the throttle a few times and it drops down to roughly 2 V.  Turned off the lights and it stays at around 2 and slowly drops to about 1 V.  I shut the car off, wait a minute or 2 and re-start.  It's charging again to 14 V (no lights) and 13.5 with lights.  Run for several minutes, blip throttle and same thing happens again. 

 

I was able to repeat the sequence again before quitting for the night.  Pretty strange eh?  The throttle blipping was to simulate driving.  I'm starting to wonder if it isn't some armature mechanical issue that only happens at higher RPM.  I guess I could let it idle for a half hour and see what happens.  Any ideas?

 

I should also mention that I have upgraded the starter box to use a large diode instead of the cut-out points.

[ArticiferTom]

You may want to look at thermal issue . Works cold opens hot ,get non- contact  lazer thermal tool and test theory .

[Pete K.]

Hi Mike, I wish I could offer something other than checking the connections at relay box, (now diode box). My '25 Dodge, #388850, still has the stupid old coil relay. I have to update this. I checked the ground strap and find it is about a foot long, attached to the upper left corner stud,( as viewed from under the hood, our passenger side) and that stud also has a little "Z" shaped strap which is fastened to the slotted round head screw in the base cover of relay box. The trailing end of the "Ground strap" goes down to a bolt on the bell housing. This cable is also insulated, probably so it can't short out another stud on the back of the relay box.

  P.S. no priming cups on cyl. head either.

[MikeC5]

Thanks Tom & Pete.  I will try the IR thermometer on the connections.  I'll check the grounding of the box too.

[GaryP65]

Can some one explain the brushes to me? I see a lot of talk about them and have no idea what they are or do. I am severely electrically challenged. I have posted on another thread about this but having no luck. I have a good battery, my switch works (added test lamp to S/G and it lit when I hit the button).

Its a late 25 12v pos ground sedan. 

[MikeC5]

Brushes basically allow electrical contact to be maintained between something spinning around to something stationary. In the case of a starter motor, the part that spins is called an armature. It has insulated copper wire wound around a shaped rotor with each end of the wire terminating at what is called a commutator. The commutators are spaced at equal intervals around the armature such that at any given time as the armature rotates the two brushes will be in contact with each end of one of the wire loop on the armature (there are several separate loops/commutators). The brushes carry current from the battery and energize the wire. A coiled wire with a current applied becomes an electromagnet. Remember opposites attract; like poles of magnet repel each other. In addition, there are coils of wire strategically placed and shaped in the generator case close to, but not touching the armature. When battery voltage is applied to these, a magnetic field is created (another electromagnet). The motor is designed so that the electromagnet created by the armature wire coils attact/repel the 'field' coil magnets with the result that the force makes the armature turn (since it is confined by bearings). As it turns, an adjacent pair of commutators make contact with the brushes and the process continues until the current is stopped. I'm sure there are some web sites with gee wiz graphics that may help explain but in a nutshell the brushes allow a rotating electromagnet to react to a stationary one.

Edited October 12, 2015 by MikeC5 (see edit history)

[GaryP65]

Mike, nice work. Very visual.

My issue now is, how do I get it to work? Now that I pulled the collar off and found the useless spring (noted on another thread), is that my sole fix? I have a mechanics manual. If I do the tests described and depending on the results, where do I go from here? See attached photo

[MikeC5]

Did you try pulling back on the brush spring arm? The spring may still be working.

[GaryP65]

Yes. It has no tension

[MikeC5]

That is a problem. If you can get someone brave enough to hold the brush down with finger pressure while you try the jumpers, it should work. Be careful...

[JACK M]

That is a problem. If you can get someone brave enough to hold the brush down with finger pressure while you try the jumpers, it should work. Be careful...

 

Use a dowel.

[GaryP65]

Hey,

I seemed to have missed a lot of response just using my phone. Now that I'm on my computer, I see some good stuff!. Maybe I'll ask the wife to hold the brush down!

 

YAY....... 

 

Once I started scanning I figured I might as go all the way so IF the nearly 18 meg PDF of the 1925 North East Equipment booklet attaches anyone who wants it can have it......

 

The PDF won't attach so I'll host it.

 

Get it there >>>http://andersonofrosholt.com/mypics/1925_North_East _Equipment.pdf

 

cahartley, I clicked your link and it tells me the page no longer exist but a site with a 59 chevy. 

[cahartley]

^ I JUST switched my website platform so that link no longer works.

You can get at AT my site (had you clicked the home page button you'd have seen my other cars).

You can get it there now....... >>> http://www.andersonofrosholt.com/just-pics/