Headlights oscillating

Page 1 of 2  
This just started.... or at least I just noticed it. With the headlights on dim and engine warmed up and idling, the brightness cycles from normal to slightly dim. Cycle time is around a second. When I rev
the engine slightly, they return to normal steady brightness.
When running with or without lights, the ammeter is just right of center, slightly charging, in the normal position.
I don't suspect a connection -- within the last 2 months, I removed and cleaned all the battery connections, including regulator and other parts when I was fixing a grounding issue.
Battery cranks start just fine. No other indications of failing battery.
Thanks folks,
Snuffy
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Snuffy "Hub Cap" McKinney wrote:

Some times one diode goes bad(opens or short)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

anyway) 12 pole 3 phase devive, and is geares about 2:1 from the crank, so at 500RPM idle would be turning about 1000RPM, making about 60Hz power (if my math is anywhere close to correct) so any cycling would be in the 1/60th second range -a very high frequency flicker, not a surge with a 1 second period.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@snyder.on.ca wrote:

There are many things one would not believe until one sees one in person.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

is NOT possible. The surge every second or so is a bad alternator - but not a bad diode.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 04 Aug 2015 18:38:18 -0500, Snuffy "Hub Cap" McKinney

It wouldn't be something silly like a loose belt by chance? I've heard of belts getting shiny and slick also. Does the heater fan do anything unusual?
--
Using Opera's mail client: http://www.opera.com/mail/

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 04 Aug 2015 19:11:55 -0500, "Dean Hoffman"

a month or so, and the unsteady lights at idle will go away when the alternator is replaced. How many miles are on this beasty, and how old?? Is it the old Aeroscare?
I had the same problem on my '89 - replaced the regulator - no joy. Replaced the alternator - problem fixed.. I managed to pick up a good recently replaced rebuild at the wreckers for $30 (about 20 years ago)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yep, the same one. About 140K miles. Is that something that can be checked out before installing a new one? They ain't cheap.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 8/4/2015 10:59 PM, Snuffy "Hub Cap" McKinney wrote:

In my part of the world, some Advance Auto Parts And Battery have alternator testers. Some even have a man who knows how to do the test.
--
.
Christopher A. Young
learn more about Jesus
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 4 Aug 2015 19:59:27 -0700, "Snuffy \"Hub Cap\" McKinney"

still "surge". A good analog voltmeter connected to the output of the alternator will show if the voltage is fluctuating.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

OK, will check it tonight. Yesterday while idling during the day, I noticed the ammeter oscillating. If I kicked the gas and released it, the oscillation stopped. Will check the belt also.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 4 Aug 2015 16:38:18 -0700, "Snuffy \"Hub Cap\" McKinney"

Could be worn out/sticking brushes in the alternator.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
In alt.home.repair, on Tue, 4 Aug 2015 16:38:18 -0700, "Snuffy \"Hub

Do you have a tachometer? Does the RPM oscillate?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

from normal to slightly dim. Cycle time is around a second. When I rev the engine slightly, they return to normal steady brightness.

parts when I was fixing a grounding issue.

RPM is steady. Oscillating lights happens at slow idle. If I increase idle speed just a little with accelerator, lights are steady.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
In alt.home.repair, on Wed, 5 Aug 2015 10:05:16 -0700, "Snuffy \"Hub

Even at steady RPM, the reguator relay goes in and out, but I really don't know at what rates. IIRC a generator needs a regulator with 3 relays, and an alternator needs 2 relays.
One of the two limits how much current goes to the field winding, but is that only for generators?
Do you have a wife with another car. I always wanted a wife with a pickup truck, but I coudlnt' find one. What's the worst that can happen, youll break down onthe way to work adn she'll have to pick you up and take you to work and the car will sit there until you can get a new alternator. Can you get one right away and replace it wherever the car dies, or would you have to be towed?
What's the voltage of the alternator, while the lights oscillate. While they say 13.6 is what it should put out, and maybe lightbulbs are designed for that voltage, really anything over 12 6 should charge the battery a little. Or say over 12.7. You said your ammeter shows slight charging. If the alternator will to completely fail, you could drive more than a day I'll bet if you have a fully charged battery. Old cars start easily and cars don't need too much current to run.
I once drove from NYC to Chicago to Indianposlis to the Pa. Turnpike near Pittsburgh. When I left NY, maybe by the time I got to Ohio or earlier, the headlights were dim, but as I usually do, I igonred the problem. The rest of the car ran well and most of my driving was in the day time.**. I drove to Chicago and around there for 2 or 3 days, Indy for a couple day, and just as I got to the big gas station near the entirance to the Pa. Turnpike (after a trip of 1400+ miles.) the car stalled and woudn't start. I opened the hood and the fan belt that drove the alternatas literally hanging on by a thread. Of course a fanbelt thread is thicker than sewing thread, maybe half a millimeter.
But the belt was no longer tight enugh to drive the alternator and I had been running on the battery for at least a couple hundred miles, and that was in the dark and again I'd noticed that the headlights weren't very bright. But the road had been well marked and I coudl follow the car in front of me, etc. . IIRC, I had a fan belt in my trunk, that I had taken from a junk yard car like mine, and I put that on, and after I got some food I got the gas station guy to come the 100 feet to my car with his portable jumping thing, and I'm not even sure he charged me, but he started me and I started driving east and charging the battery. And that was the end of the story.
Now I was in my 20's and people our age don't live like this, but otoh, if I were just drivign around town, and I had someone to come and get me, even the number of a taxi-company. I'd still do it that way. Because you don't yet know that the alternator is bad or that you'll *have* to replace it before the car fails permanently for some other reason.
In the old days the oil light would flicker on and off at idle and that was normal, even though it's a lot more imporant that a few little light bulbs.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
After serious thinking micky wrote :

I'm not sure but to my long memory Alternators have had solidstate regulators and no relays since they were invented. :-Z
--
John G Sydney.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
In alt.home.repair, on Thu, 06 Aug 2015 16:26:00 +1000, John G

You're definitely wrong about that. Atlternators made their first showing in large numbers maybe in 1965 or about then and all of them had relay-based regulators, with two of them, for several years. Then some had relay-less regulators within the alternators, but they made cars with both styles for a while.
I guess I was forgetting sold-state regulators and assuming no matter what year his car is, he had relays. My mistake. (I don't know if they ever made external soldi-state regulators.)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
In alt.home.repair, on Thu, 06 Aug 2015 16:26:00 +1000, John G

Maybe you were thinking about the diodes in the alternator**. If they had had to depend on diode tubes, whether glass or metal, instead of semi-conductor diodes, I don't think alternators would have been possible.
**For the youngun's here, if there are any, generatos had a commutator and generated DC current. Alternators had two rings for the two brushes, no commutator, and generated alternating current, hence the name, and used diodes to turn it into DC.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Alternators became standard in the early sixties, and Ford and GM were still using electromechanical regulators on their alternator systems up to 1978-79. Mazda still used some as late as at least 1981 and Toyota untill 1986. Chrysler used then till about 1979.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

There are no relays in toda's regulators. They are all electronic. Some regulate the feild with a PWM, others just switch resistance like the old relat type.
Generators needed to control maximum current as well as maximum voltage, AND disconnect from the battery when not charging(cutout) so the generator didn't "motor" and draw all the power out of the battery

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.