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Voltage Regulator Adjustments??? Bad Generator???

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lesingepsycho

Jedi Warrior
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Hello everybody,

Background: I spent yesterday replacing a bad water pump on my mothers '68 Midget. She's keeping everything stock on her car and so has a dynamo/gnerator and external voltage regulator. After putting the SU's that I rebuilt this winter on, I was able to get the car to where it idles at about 1000RPM or less, but when it is idling that low, the red ignition light comes on indicating that the car isn't being charged. (I learned the hard way to take that little red light seriously!)

My question: Is this something that can be adjusted in the voltage regulator so that the battery recieves a charge when idling or is this a sign of a weak generator? If it is a weak generator, is it worth while to be rebuilt or is it better off to buy new?

Thanks in advance /ubbthreads/images/graemlins/cheers.gif

JACK
 
Supposedly if you follow the procedure in most Haynes manuals or similar you can adjust the regulator to cut in a little lower. I, however, have never been able to adjust these. I'm not patient enough. The last time I just gave up and bought a new control box from VB.

If you want to test the generator yourself, you can start with this procedure from AutoBooks by Kenneth Ball:
1) Make sure the belt isn't loose.
2) Make sure everything electrical on the car is turned off.
3) Remove the two wires from the generator and use a short length of wire with clips or lugs to join the two terminals together.
4) Start the engine and allow the engine to idle.
5) Use a volt meter to measure the voltage between the joined generator terminals and chassis ground.
6) Bring the RPM up to 1000 RPM or so and watch the volt meter. The reading should increase but not exceed 20 volts.
Indications:
A) If the reading is only about 1 volt, the field windings may be at fault.
B) If the reading is about 5 volts, the armature may be at fault.
 
If you determine it is a bad generator -- I upgraded mine with an alternator (72 Camaro) for less than $40. Fabricating the bracket was a bear but I now have more juice / more reliable for less $$. Since the alt includes a regulator -- was able to get rid of the older (questionable) voltage regulator.

Also -- upgraded headlamps to halogen and I feel much safer.

Geo
 
Hi Jack, I think your obsevations are typical of most generator equipped cars. If the light goes out and stays out at road speeds and is up to starting on a daily basis I do not think you have a problem at all.--FWIW---Keoke
 
Thanks guys,

I would love to put an alternator on there and be done with it but it is my mother's car and she wants to keep it stock.

I figured the light coming on was typical... now. But I don't figure it was typical when the car came off the assembly line which means something must not be working to its full potential. If it were my car I wouldn't worry about it but since I'm not going to be driving it (read: not there when it breaks down) but I will be the person who gets called when my Mom is stranded on the side of the road or in a parking lot somewhere... you know what I mean? There's no way for ME to really know if it will be up to starting on a daily basis until something happens.

Anyways, thanks for the tips everyone. Next time I head over to her house I'll be going armed with my multimeter and see if I can't get something figured out. That wasn't my goal when I was there the other day so I didn't have my electrical diagnostic tools. Wanted to do the research and get everyone's opinions before I set off on a wild goose chase.

Thanks again /ubbthreads/images/graemlins/cheers.gif

JACK
 
[ QUOTE ]
Supposedly if you follow the procedure in most Haynes manuals or similar you can adjust the regulator to cut in a little lower. I, however, have never been able to adjust these. I'm not patient enough. The last time I just gave up and bought a new control box from VB.


[/ QUOTE ]

I'll second these comments! I spent hours on multiple occasions trying to get the control box on my TR4 set correctly after blindly (and stupidly) turning adjustment screws. My initial problem was just the opposite. I thought that my system was receiving too much current during at speed conditions.

If you plan to try to adjust the control box, you'll need access to a high quality moving coil voltmeter. I don't think you'll be able to set it properly with a digital voltmeter. I have detailed instructions that I'd be happy to e-mail to you if you'd like.

BTW... I ended up buying a new control box as well. /ubbthreads/images/graemlins/smile.gif
 
Kurtis, I've often wondered why the instructions said to use an analog meter. I'd always assumed that it was because that's all that was available when these cars were built. Did you find that you had any better luck with an analog meter?

Jack, I'd check out the control box and generator regardless of what the long term solution is. Yes, LBCs tend to have the ignition light flicker but it usually happens closer to 600 RPM, not 1000. That said, perhaps you could reach a compromise with your mom and get away with putting a slightly larger pulley on the generator. It would look stock to all but the purist but would give you effectively higher generator RPM at idle.

Good luck. Let us know what you find out.
 
[ QUOTE ]
Kurtis, I've often wondered why the instructions said to use an analog meter. I'd always assumed that it was because that's all that was available when these cars were built. Did you find that you had any better luck with an analog meter?


[/ QUOTE ]

First of all, I'm somewhat electrically challenged. To me, electricity is just a lot of sparks and magic. However, my understanding is that you will not get a steady reading with a digital voltmeter because of the way the control box actually regulates the voltage (by cutting it in and out?). I did indeed notice that it was nearly impossible to even get a reading on my digital voltmeter under most circumstances. The display kept jumping all over the place. My understanding is that an analog meter will help steady the reading by "averaging" it. I had a cheap analog meter that I used, but the settings given in the instructions demanded more accuracy than my analog meter was capable of reporting.

Does that make any since? In civil engineering, we had a choice between a circuits class and thermodynamics as a required engineering elective. I chose thermo. /ubbthreads/images/graemlins/smile.gif
 
I'm a mechanical engineer. I survived thermo... thought I'd aced every test only to get a B or B- on every one. I was forced to take one EE course from which I did learn a lot and which gave me the courage to dabble in electrical/electronics a bit.

Your comments make perfect sense to me. In fact, I hadn't thought about the relays opening/buzzing the way they do until you mentioned it. For your future reference, if you're measuring the output of the voltage stabilizer for gauges the same comments apply. You can't use a digital meter on that output either as it bounces too much. The bouncing is "fast" on most new units and can be downright slow on old ones.

Thanks for the info.
 
[ QUOTE ]
I'm a mechanical engineer. I survived thermo... thought I'd aced every test only to get a B or B- on every one. I was forced to take one EE course from which I did learn a lot and which gave me the courage to dabble in electrical/electronics a bit.

[/ QUOTE ]

I was wishing I'd taken the circuits class when I saw the question breakdown on the EIT exam. Over half of it was EE related crap, and no pure civil! Fortunately my dad is an EE. I had him give be a few crash night courses in circuits. It must have worked, because I passed it.
 
When I took the EIT I was sucking wind on the EE portion. At that point in history all the questions seemed to be about 3-phase power and industrial controls. The only course I'd had was on circuits and semiconductors. I made a lot of educated guesses and a lot of random choices on that portion of the test.
 
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