Generator charges, then it doesn't.

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Model T Ford Forum: Forum 2014: Generator charges, then it doesn't.
Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, May 29, 2014 - 05:52 pm:

The area of my greatest incompetence is electrics, so I'll ask for a heads-up on what to look for before I go to work on this problem. The generator on my touring worked, then didn't. I cleaned the commutator. The generator worked, then didn't. Again I cleaned the commutator. Again, the generator worked, then didn't. Now even a thorough cleaning doesn't get it charging. Maybe the cleaning was doing something, or maybe this was a case of post hoc ergo propter hoc. Any suggestions?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR on Thursday, May 29, 2014 - 06:06 pm:

Do you have one of John Regan's voltage regulators on it? If not, I'd advise getting one.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Andy Loso St Joseph, MN on Thursday, May 29, 2014 - 06:10 pm:

Cutout or voltage regulator? Probably needs more than just a cleaning. I rebuild them, come on up and we can do it together. They require some special tools to do a total overhaul. Do you have the manual, it basically tells you what you need to do, for the most part. Feel free to call or email if you want help.

alosoatq.com/320-293-1953


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Thursday, May 29, 2014 - 06:11 pm:

I can't speak to generators, but all the times I've encountered erratic charging on my Mopar alternators the cause has been worn out brushes or weak brush springs.

Chapters XXXVI and XXXIX in the service manual cover generator and charging system troubles.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Thursday, May 29, 2014 - 06:34 pm:

What's the condition of the brushes and springs. Perhaps during cleaning, you moved the brushes. If they don't move freely or the springs are too weak to keep pressure on the brushes, they loose contact. How the brush pigtail is oriented and attached to the brush holder can also affect the contact pressure.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Brian Eliason on Thursday, May 29, 2014 - 06:39 pm:

Steve,
You may need to undercut the mica insulation in the commutator. If the mica between the bars is flush with the tops, it can result in the brushes smearing the mica onto the contact surface. Voila; no charging! If you don't have easy access to an undercutter, it can be done by hand with careful application of a piece of a fine tooth hacksaw blade. The trick is to find a blade that is no wider than the space between the bars so you aren't removing much copper. You only need to go deep enough that the brushes won't touch the mica, then remove any burs left on the edges of the copper bars so they don't dig into the brushes. The pictures are from a generator that would not charge. You can see the smearing of the mica before it was turned and undercut. If your gen won't charge after cleaning the comm, you might clean the face of the brushes in case they have a layer of mica on them as well. Good luck! BrianBefore undercuttingAfter undercutting


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, May 29, 2014 - 08:27 pm:

I didn't move the brushes for cleaning, so it's not that. But I also haven't undercut the mica or checked to be sure all the springs are tight. I have the Regan VR, but I don't want to put it on until I have the generator operating reliably. I'll get this. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Thursday, May 29, 2014 - 08:53 pm:

Steve:

Commutator bars have to be cleaned up..... I use a strip of sandpaper backed with a wood wedge to clean bars while generator is running on the engine..... charging rate re-established.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Thursday, May 29, 2014 - 09:20 pm:

Steve,

You might want to check out this site :-) :-) :-) :-)

http://www.dauntlessgeezer.com/DG80.html

The author makes a strong case about buying and reading the books before taking a screwdriver to task...

I've used screen capture and highlighted the book you apparently should read as it talks about setting brushes and cleaning comm's...if its good enough for that dauntless geezer guy, it is usually good info :-):-):-)



(just couldn't resist :-) )


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, May 29, 2014 - 10:03 pm:

Bob, I did that and it worked until it didn't. :-)

George, I've seen that page and I did take that guy's advice and look at the book. Just wondered what would be the first things people here would suggest to check.
:-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By michael grady on Thursday, May 29, 2014 - 10:09 pm:

The first thing I'd check would be this forum. Seems you've done that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Thursday, May 29, 2014 - 10:14 pm:

ahhhh....ok then....first place I'd look then...brush spring tension...you fiddle, it works...run it a bit, doesn't. Brush just may be riding up somewhere but a thou or so and the fiddle then makes contact....for a while.

Someone else can comment on how much, but I 'think' there should be some noticeable tension on the brush when seated.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Eyssen - Abilene TX on Thursday, May 29, 2014 - 10:48 pm:

Steve: I had a similar problem of late. I did not see in these posts that you tried to run generator like a motor. I had one that ran fine after adjusting the 4 screws on the back to not spin, and then dropping the third brush to motor. Put back on car and would not charge----after about several days of off and on, finally took it to a guru who got it to gen. Apparently the curvature of the brushes were just enough that it would motor with 6 volts, but not gen on its own when on the car. Now it gens like crazy. Check your brush curvature a see if this helps. Regards, Tim


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Thursday, May 29, 2014 - 11:01 pm:

Steve:

You are absolutely correct not to install the VR to this generator. Installing a new VR to a questionable generator results in a questionable VR. VR is NOT a cure for a sick generator. VR is a great addition to a good electrical system on your T. It adds life to generator, battery, and lights but adds only to repair costs if installed to a sick system. Take Andy up on his offer. Working along side someone who has done it is a great way to learn.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, May 29, 2014 - 11:02 pm:

Going to be busy with other stuff for the next week. Maybe after that I can take the generator off and dig into it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Thursday, May 29, 2014 - 11:30 pm:

You certainly have the capabilities to re-build it Steve. I've done a few and I can tell you this: if it hasn't been off and at least cleaned in 20 or more years it needs to be done and it usually makes a hell of a difference. Loads of junk builds up inside. I totally agree with undercutting the mica. It can be done with a piece of hack saw blade and doesn't need much removal. Just get it below the copper. Something is disconnecting in your unit either through heat or vibration. Check or replace the springs, brushes and bearings. Not a hard job. You've done harder stuff.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Todd on Friday, May 30, 2014 - 12:05 am:

When using a piece of hacksaw blade to undercut the mica, use a used fine tooth one and grind the sides down so that it's more or less flat and just the same width as the mica.
If you're unsure about the cut-out working, use a 40 amp or so diode in it's place temporarily.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Gruber- Spanaway, Wash. on Friday, May 30, 2014 - 12:41 am:

Brushes might be sticking in their holders.
I've had this happen and can make it work erratically.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George Clipner-Los Angeles on Friday, May 30, 2014 - 01:45 am:

Yeah, my dad had the same thing with his generator.
Rather thin rebuild and wanting to go to 12v. he just got an alternator instead. He would occasionally drag the pointed end of an Ice pick across the mica worked for about five trips only and then he had to do it again.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Friday, May 30, 2014 - 09:59 am:

Brian
I agree with your comments about undercutting and commutator finishing, but the commutator photos you posted should not be interpreted by anyone seeing that as an armature that should be reused after the commutator has been finished.
The armature depicted in your photos has been severely overheated (most likely by a "run away" generator not connected to an appropriate current sink), most, if not all, of the solder has been slung out of the segment to winding slot connections, the fiber insulators are burnt and armature has been so hot the wood winding wire retainers in the lamination are badly burnt.
Anyone rebuilding a generator should NOT try to reuse an armature in this condition.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Friday, May 30, 2014 - 10:18 am:

This discussion is a good example of why I love this forum. It has a mixture of humor, good suggestions from personal experience, and advice from real pros. Well done gentlemen, and thanks to all.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, May 30, 2014 - 10:37 am:

Are you sure the generator is not charging? Put a voltmeter from the output to ground on the generator side of the cutout and see if it is putting out a charge. If it is charging, the problem is elsewhere.

Loose connections anywhere between the generator and the battery can cause irradic output. Dirty contacts in the cutout or if a diode, a burnt out diode, can cause the problem.

If you have a voltage regulator, it will show a high charge right after you start the engine and then when the battery is fully charged, it will drop off to almost 0 charge. But if you have a voltage regulator and it is running and you turn on the lights, it will still show around 0 charge. If it shows a large discharge with the lights on, your generator is not working.

A couple of most common problems with the generator is dirty commutator. The other is worn out brushes. as the brushes wear, they will finally get to the point where the spring will not push them against the commutator. Then the generator will stop charging. This is especially common when the commutator has been turned down numerous times so that the brushes must be pushed down farther to make contact.

Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Brian Eliason on Friday, May 30, 2014 - 11:41 am:

Ron, I agree that it would be foolish to run an armature in that overall condition. In this case I guess I'm an adventurous fool. It is charging now, but I'm sure it could fail any moment. Thanks for bringing that up. Brian


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Friday, May 30, 2014 - 12:48 pm:

I'll add one thing to Norman's third paragraph. We drive our cars faster and longer than they typically were when they were new...also typically very little night driving. There is no need to run the generator beyond about 4A full output for the generator to quickly recover the battery from a start. If you do this, you'll see three things: your generator will last longer, your (fiber) timing gear will last longer, and you will see some discharge on the ammeter when burning the headlights. Even for a few hours, it shouldn't make a dent in the output of the battery. So you may in fact see a discharge on your ammeter with the lights on and still have a functioning generator...I think the key is defining "large discharge".


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