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Technical Need step by step charging system diagnosing procedure

Discussion in 'Traditional Hot Rods' started by chiro, Apr 25, 2021.

  1. chiro
    Joined: Jun 23, 2008
    Posts: 937

    chiro
    ALLIANCE MEMBER

    Hi all,
    Yes...I've done a search. Admittedly, electrical issues are not my strong suit. Issue is no charging on my 59AB flatty in my AV8 '30 coupe with a 12 volt generator and system. Here's the background:
    Began having charging issues since 2019. No issues before that. Two terminals on my generator; Armature and Field. Ammeter started showing NOTHING. No charge, no discharge. Came to realize the gauge took a shit. Deleted ammeter and went to a voltmeter instead. Reading at voltmeter was consistent at just over 12 volts while driving. Had the coupe out at night and the voltmeter was reading under 10 volts with the lights on. Not good.
    Brought the regulator and generator to a reputable rebuilder (they do all the local firehouse stuff so you know they're good). Generator bench tested great. Voltage regulator no good. They got me a new regulator and matched it to generator and flashed it.
    Installed and same issues. Voltmeter reads just over 12 volts when running at speed. Mostly voltmeter shows just over 12 volts when just cruising. Took the car to the rebuilders shop. He put meter on the generator when car was running and it checked out good. Said to check the wiring for resistance with digital ohm meter. Now, voltmeter just reads the same voltage that the battery reads when the car is not running. Voltmeter does not move at all from that voltage while engine is running.
    I checked all the terminal ends and all the grounds on the car. Everything looks good.
    Guy also said to run a test lead from the housing of the generator to the Neg. Batt. terminal. Did that with no change. I have a battery cut off switch at the negative terminal. Some on here have said that if the battery is taken out of system, the VR will need to be reflashed but I have never had that be an issue with a generator vehicle EVER.
    Anybody have a step by step procedure for diagnosing this system?
    How does one TEST a voltage regulator anyway? Like I said, electrical stuff is not my strong suit, but I want to learn so...
    Thanks,
    Andy
     
    Last edited: Jun 23, 2021
  2. 325w
    Joined: Feb 18, 2008
    Posts: 5,608

    325w
    ALLIANCE MEMBER

    Volt meter is reading the voltage of the system. When you turn your lights on the generator is still putting out 13 volts. But it’s not showing on the voltmeter. The headlight circuit is the problem. You have a really bad ground in my opinion. Go it and check the grounds in all the running lights. This is what I would do for a start. Headlights pull lots of voltage when something is not ground right. I use star washers on all grounds. If you have a ground on powder coat fix it right.
     
  3. While taking connections for lights apart, use dielectric grease on connectors during reassembly.
     
    hotrodharry2 likes this.
  4. G-son
    Joined: Dec 19, 2012
    Posts: 794

    G-son
    Member
    from Sweden

    Just over 13V is a bit low, thats about the voltage you use for charging backup batteries that are on charge 24/7, high enough to charge the batteries eventually but low enough to not kill them by the constant charging - the charging is quite slow and that's just fine in those systems.
    In a car where you use a lot of current to start the engine and then want to get the battery back to full relatively fast you use a higher voltage for faster charging. Something more around 14V.

    As for checking resistance, ordinary meters are not sensitive enough to measure the low resistance we usually have issues with in electrical systems. But set them for measuring voltage instead and keep the current running through the wiring you can easily measure the voltage drop you get across any place where there's resistance.
     

  5. Assuming the generator and regulator are good as per the rebuild shop, perform these checks in this order...

    1. Make sure the voltmeter is connected properly. They don't connect the same as an ammeter, the two wires that were connected to the ammeter should both be installed on the + terminal of the voltmeter and the other terminal should go to ground. I will note here that an ammeter is a better choice for monitoring the charging system when using a generator.
    2. Unless your regulator is mounted directly to the generator case, check/install a wire from the generator case to the voltage regulator base/case. With the vehicle running and a load on the charging system and using the 10 or 20 volt range on your meter, check between the generator case and the regulator base. If you read more than .1 volt, you have a poor connection between them and this needs to be corrected. I'll note that generators need about 1500 motor rpm to reach full output.
    3. Still having issues, then check the individual wires for the charging system. Using the same meter setting and under load, check between the ends of each wire. If any readings are above .2 volt or so that is showing a poor connection and/or a damaged or too-small wire. Correct any problems found.

    If after all this you still aren't showing proper output, connect a temporary jumper between the 'arm' and 'field' terminals on the generator (again, with the motor running) and if output then goes up to 14+ volts you have a bad regulator. Quality on new generator voltage regulators these days are crap, don't be surprised if it's bad.
     
    pprather and jaracer like this.
  6. jaracer
    Joined: Oct 4, 2008
    Posts: 1,107

    jaracer
    Member

    Ditto on the quality of today's voltage regulators. I find they crap out at about 5 years. The problem I am seeing is that the cut-out relay just won't close like it is supposed to. I've tried adjusting the relay with little luck. If I can get it to close, it will stay closed until you shut the car off. On a restart, it simply won't close. However, the cut-out relay doesn't sound like it is this gentleman's problem. He really needs a good automotive electrician who is familiar with generators. Preferably someone that can operate a VAT 28.
     
  7. jaracer
    Joined: Oct 4, 2008
    Posts: 1,107

    jaracer
    Member

    What is the voltage at the BAT terminal on the regulator with the engine at 1500 rpm? It should be close to 14 volts. If it isn't, the voltage regulator portion of your regulator needs to be adjusted. (your voltage regulator has three portions, cut-out relay, voltage regulator, current regulator) If it is, then you have problems with the vehicle wiring. You would have to start voltage drop testing each feed wire and ground to find the problem.

    I should point out that you need a good, fully charged battery for the above test to be accurate. If the open circuit voltage at the battery isn't 12.6 volts or above, then the voltage at the BAT terminal won't go up to 14. The old generator test equipment such as a VAT28 had the ability to simulate a fully charged battery so that you could check the voltage regulator setting.
     
  8. TRENDZ
    Joined: Oct 16, 2018
    Posts: 310

    TRENDZ

    Could you give the details of your “ammeter delete”? Are the two wires now connected to each-other?
     
  9. chiro
    Joined: Jun 23, 2008
    Posts: 937

    chiro
    ALLIANCE MEMBER

    ^^^Yes.

    Thanks everyone for the suggestions. Keep them coming. You guys are a wealth of knowledge and have been very helpful in the past when I've had difficult problems with this project.

    Blew my back out yesterday working on the Bad Bitch so I'm arm chair hot rodding today. Lol. Fixed a turn signal switch problem, oil change on the flatty and new tires put on yesterday. Add that to cardiac rehab Friday and a 6 1/2 hour walk around Carlisle on Thursday and my broken body yelled "uncle" loud and clear. I'll get to the suggested fixes later this week hopefully.
    Andy
     
  10. Take care of yourself Andy, the car will be there when you are doing better.
     
    chiro likes this.
  11. Truck64
    Joined: Oct 18, 2015
    Posts: 4,751

    Truck64
    Member
    from Ioway

    No, and no. First thing to keep in mind, it isn't the voltage regulator that ever needs "flashing" or polarization.

    The generator is what gets polarized. Ordinarily it holds residual magnetism from the time of manufacture. Or it's supposed to anyway.

    Disconnecting the battery, or the regulator, or even swapping out the generator doesn't require polarization It won't hurt anything to polarize or "flash" a generator - provided it is done correctly. But it only takes a second to ruin a voltage regulator when it is done incorrectly.

    You need the shop manual, or period troubleshooting docs. There were different systems used, and they have different connections and test procedures. An ammeter capable of measuring 30+ amps is part of the kit, most people don't have these. Analog voltmeters are required for some of the tests as a digital VOM will just display gibberish.

    For all that though, you want to make sure that the grounds, cables, and connections are clean, tight and low resistance. Just a few hundredths of an ohm excess will cripple current output of any charging system. Voltage charge readings are only part of the story, but you'll see close to 15 volts or higher in correctly operating generator systems.

    Don't f&@k with the voltage regulator adjustment, particularly to try and work around corroded, high resistance grounds and wiring. The VR needs to be at the same ground potential as the battery and generator. A "voltage drop test" is your friend here.
     
    46international and chiro like this.
  12. Mr48chev
    Joined: Dec 28, 2007
    Posts: 29,563

    Mr48chev
    ALLIANCE MEMBER

    Steve hit on one generator absolute in post 7. They normally will not put out a decent charge until the engine rpm hits around 1500 and normally don't put out much of anything at an idle. If you are testing with the engine at an idle of around 6oo rpm that is probably why you aren't showing any voltage while testing.
    The other thing that he mentioned (check connections) is a good one as pretty paint on engines, brackets and accessories serves as a great insulator when it comes to electron flow.
     
  13. chiro
    Joined: Jun 23, 2008
    Posts: 937

    chiro
    ALLIANCE MEMBER

    All paint on all ground connections has been sanded off to shiny metal to ensure good ground contact. I made sure of that when wiring the car. All testing has been done with engine at high idle, at least 1500 RPM. I think that I may be getting a false sense of what's going on since I took the ammeter out of the system when it took a shit and replaced it with a voltmeter. I know the voltmeter will read volts only in the system and as long as it's reading at least 12 volts the system should be good. I'm certain that the headlight circuit has bad grounds because when I initially wired the car and turned on the lights they were quite dim, yellow almost. At the time I unbolted the headlight stands on the vintage and ancient Guide headlights and made the metal shiny at the attachment points on the frame horns and the lights were better. I think I need to revisit that spot and the ground connections inside the buckets.
    Also, I'm going to add an ammeter back into the charging circuit in the car to see what that tells me. I have several laying around in various boxes in the garage. I may even have one that matches the rest of the gauges in the dash. Point of interest; the ammeter that failed was a NEW Stewart Warner gauge. Not a vintage gauge. Probably made in China. New stuff sucks. There is no quality manufacturing anymore since it all went overseas.
    Also, as of this morning my back is still screwed up pretty badly so it's only arm chair hot rodding at this point. Once i'm good enough to bend over without screaming in pain I'll get out there and give it a go. Probably not till next week owing to how this has gone in the past.
    Andy
     
    Last edited: Apr 26, 2021
  14. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,274

    sunbeam
    Member

    Remove the cover from the regulator you will see three sets of points the one next to the BAT terminal is the reverse current cutout as you increase the RPM you should see the points on the cutout close. If they do not close the system is not charging. They will only close when the generator voltage is more than the battery voltage. You can full field the generator but to do that you need to know what generator you have.
     
  15. I would start by removing the cut out/off switch at the battery. In my experience, they can be a major source of problems.
    I gave up on generators LONG ago. One wire alternator for me. Never a problem, except hearing how lazy I am for going that way.

    Ben
     
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  16. Truck64
    Joined: Oct 18, 2015
    Posts: 4,751

    Truck64
    Member
    from Ioway

    It could be something as simple as the armature brushes are sticking in the holders. They need to present a solid contact patch against the armature. The brush holders are spring loaded, sometimes as they wear the brushes hang up and don't take up the clearance like they should. Spool the engine up to around 2000 RPM with the headlights on HI beam & heater fan running and measure the voltage directly at the battery posts. It will sag a little but should be 14.x volts, the charging system is always tested under load.

    Generator charging systems are similar to contact point ignition and drum brake systems in the sense they work fine when setup and adjusted properly, but there is all kinds of arcane lore and minutiae & BS that nobody remembers anymore, and truth be told not all that many guys had a very good handle on some of that stuff back then, either.

    People want to drive their cars, not wrench on them by the side of the road. I enjoy (usually) building and maintaining obsolete systems, but alternators don't need periodic routine maintenance.
     
    firstinsteele likes this.
  17. chiro
    Joined: Jun 23, 2008
    Posts: 937

    chiro
    ALLIANCE MEMBER

    ^^^Agree with you completely. I'm pretty good with maintenance on this obsolete period correct build. I took me a LONG time to complete it and years of scrounging period correct parts and refurbishing them. Hell, I collected parts for almost three years before i even started fabricating and then it was another four years before the car even moved under it's own power. Another year until it was roadworthy but I was still working so the build happened mostly after work and on weekends when the kids weren't around. Then I decided to make it a COUPE and sold the sedan body and went through that changeover for mostly a year. It was a good switch. The car is much tighter and much more enjoyable. I do enjoy the problem solving. I have been involved with ancient vehicles for over 45 years. My first was a straight 8 '40 Oldsmobile coupe when I was 14 years old. That was my daily when I was in High school. Not many others since then but a couple generator cars for sure. My '55.1 Chevy 1/2 ton with 12 volt generator has been absolutely problem free the entire time I've owned it for the last 15 years and the genie was a used unit when I converted to 12 volts so I know this should be simple really. In fact, when I built the A, I used the same wiring harness that I used for the truck because I was familiar with it and it has been trouble free for so long. I just adapted it to the A. It was not hard to do and has worked out pretty well.
    Andy
     
    Last edited: Apr 28, 2021
    Truck64 likes this.
  18. Truck64
    Joined: Oct 18, 2015
    Posts: 4,751

    Truck64
    Member
    from Ioway

    Those "obsolete" systems are a lot more rugged and reliable than they are given credit for today. I used to spend a lot of time poking and rattling around in very remote high desert and intermountain areas in Arizona and Utah, national forest, bureau of land management, that type of thing. Can't get enough of it, once it gets in yer bones it doesn't go away.

    Nobody told me this was a completely crazy fool thing to do, which is probably just as well as it wouldn't have made any difference.

    Never had any trouble and preventive maintenance at that time - on the generator, points, brakes and such was minimal at best. I didn't know better. Not only original brakes, I'm pretty sure it was original brake fluid. If it started and ran, stopped, that seemed to be good enough. It is true had something broke in some of those places I'd have been right and proper fooked. Need to get back out there and do it again, got the old war wagon all tuned up and ready to go. I'd like to see Route 66, it's on the bucket list.
     
  19. chiro
    Joined: Jun 23, 2008
    Posts: 937

    chiro
    ALLIANCE MEMBER

    Okay guys,
    Part of the problem MAY be that the wiring harness I used on the build was for a '54 Chevy 1/2 ton. I had experience with this harness on the truck build and it hasn't given me a lick of trouble at all on the truck for over 12 years so I thought, "Why not?". It adapted really well to the hot rod application. As such I used a 12 volt voltage regulator for a '58 Chevy with the flathead generator in this harness. When I went to have the generator checked out by the rebuilder, he asked that I bring the VR so he could "match" them up. MAYBE (I don't know), but MAYBE I need to use a VR that's specific to the generator for a flathead???? Can anybody tell me if that could be the issue. Also, I'm not sure of the year of the generator for the flatty. A very knowledgable parts guy told me that my gennie is a cobbled together unit. It has features of several different years. I can tell you that it has a fan mount pulley on the front of it and both terminals are mounted on the BACK of the unit if that helps. Still scratching my head.
    Thx.
    Andy
     
  20. jetnow1
    Joined: Jan 30, 2008
    Posts: 1,829

    jetnow1
    ALLIANCE MEMBER
    from CT
    1. A-D Truckers

    Hope your back feels better soon, I bet you will solve this as soon as you are able to work on it. Let us know what yoiu find.
     
  21. Truck64
    Joined: Oct 18, 2015
    Posts: 4,751

    Truck64
    Member
    from Ioway

    Yeah, you will need to make sure the VR and generator get along well together. I don't know the particulars on that setup, but in later years it would have been "No F'ing Way"; because of the way the field coils are grounded, GM and everybody else used a type "A" system and Ford known as type "B".

    The idea of bringing both regulator and generator in together to the motor shop is a good one. He can test for proper generator voltage and current output, cutout, and the rest of it.
     
  22. chiro
    Joined: Jun 23, 2008
    Posts: 937

    chiro
    ALLIANCE MEMBER

    Update. I polarized the generator by doing the "flashy" thing between the BATT and FIELD terminals at the voltage regulator. Took it for a looong drive and it's now charging. Gets up to 13 volts as needed at speed, then settles in at just over 12 volts according to gauge in car. Apparently the rebuilder was incorrect when he told me it had already been polarized OR it just needed to be polarized once installed in the car. Either way, all is good now. Thanks guys.
    Andy
     
  23. Lloyd's paint & glass
    Joined: Nov 16, 2019
    Posts: 4,861

    Lloyd's paint & glass
    ALLIANCE MEMBER

    I've had a couple that i had to polarize constantly. But I've also pulled the cover off of the regulator and filed the points, and cleaned them with a dollar, just like ignition points, and fixed my charging issues.
     
    Budget36 likes this.
  24. chiro
    Joined: Jun 23, 2008
    Posts: 937

    chiro
    ALLIANCE MEMBER

    Update on this thread. Car was charging great and seemingly running better too. Took for several long drives, including a 3 hour cruise (hmmm…that sounds familiar). Got in the other day and no charge. No change in ammeter and nothing above 12 volts at voltmeter. Figured bad VR so I replaced it. I polarized again just for kicks and nothing. Took for a drive and checked voltage again after returning at battery. Before going out battery read at 12.2 volts with engine off. After returning, it read 12 volts so I’m definately not charging. Pulled genie and VR today and bringing both to a local rebuilder to have them checked out. This is driving me batty.
    Andy
     

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