Fluctuating/Bouncing Amp Gauge

[avgwarhawk]

Did a search of the forums without much luck. Going to check my manual and also what all here may know/experienced.  My amp gauge in my 54 Buick will from time to time bounce up and down. Not wildly.  But for several miles it will bounce up and down. Other times it steady in the middle. The system is charging the battery and testing shows a good charge.  What are the possible causes of a bouncing amp gauge needle?  As a side note, the battery is known good. 

Edited April 14 by avgwarhawk (see edit history)

[EmTee]

Sticky (i.e., dirty) regulator contact?  Worn generator brushes/sticky brush holder?  I'd probably start by by carefully running a contact file through the regulator contacts once or twice, followed by a piece of paper or thin cardboard soaked with contact cleaner.  If it persists I'd try to get a look at the generator brushes, maybe with a dental mirror & flashlight; otherwise remove and inspect.

[avgwarhawk]

Will do. May be a bit until I get to it.  I'll keep you posted. 

[Bloo]

Mechanical regulators regulate by bouncing or vibrating the points. The bouncing can be slower than normal due to excessive resistance in the wiring, sometimes leading to more noticeable flickering in the lights. If it is not objectionable, I wouldn't worry about it too much. Maybe clean all the connections. Keep an eye out for a degraded crimp getting hot. I would also do the things @EmTee mentioned.

[NailheadBob]

Once you have check above suggestions and if still have issue,

 

Another item when checking is the nuts holding the wire harness connections on back side of amp gauge if maybe vibration has worked them a little loose?

 

Bob

Edited April 14 by NailheadBob
update (see edit history)

[avgwarhawk]

2 hours ago, NailheadBob said:

Once you have check above suggestions and if still have issue,

 

Another item when checking is the nuts holding the wire harness connections on back side of amp gauge if maybe vibration has worked them a little loose?

 

Bob

I'll take a look. Always best to check the entire system.  I can say it's not let me down in the 13 years I have owned this Buick. 

[avgwarhawk]

5 hours ago, Bloo said:

Mechanical regulators regulate by bouncing or vibrating the points. The bouncing can be slower than normal due to excessive resistance in the wiring, sometimes leading to more noticeable flickering in the lights. If it is not objectionable, I wouldn't worry about it too much. Maybe clean all the connections. Keep an eye out for a degraded crimp getting hot. I would also do the things @EmTee mentioned.

No flickering of lights.  Cleaning all connections can never be a bad thing. 

[Bloo]

When the battery charges to almost normal system voltage, the voltage regulator points open and drop the charge rate way back to something that works out to a trickle charge if the battery is full. But, with the generator cut back, the system voltage drops a little, points close, generator comes back on high, instantly gets to system voltage, points open, cuts back, BZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ.... ad infinitum until the battery gets so full it doesn't drop below system voltage with only a trickle charge.

 

Edited April 14 by Bloo (see edit history)

[KAD36]

Was going through spare regulators in the garage the other day because somehow I own 5 yet only have 1 car, but one of them has similar problem. It’s an NOS Delco PN1118839E, which appears to be a 30 amp unit but not sure what E signifies.  Have had it awhile, swapped it in and ammeter bounces about 1/4 inch all around 0, voltage at battery fluctuates 13.3-14.8, independent of idle speed and electrical load.  Ran points file over contacts 1 stroke then thin cardboard with cleaner between them - no luck. Maybe bad ground? Stuck the old aftermarket one back in for now and it’s pretty solid, typical slight jitters around 0, 14.7 at battery.  
 

I’d like to get it right because it has the screw adjusters on it, vs the newer tab type which if anyone has ever tried are a PITA to adjust and my finding is the temperature compensation for charging especially at hot isn’t very consistent.

Curious what you find out.

[EmTee]

7 minutes ago, KAD36 said:

I’d like to get it right because it has the screw adjusters on it...

Maybe that's the issue (adjustment).  I think both gap and spring tension are important and maybe the shop manual has values and procedure?  I'll bet @Bloo has some thoughts on that.

[KAD36]

22 minutes ago, EmTee said:

Maybe that's the issue (adjustment).  I think both gap and spring tension are important

Yes sir they are. I do have the Delco publication for regulator specifications and adjustment procedures.  Perhaps the voltage or cutout relays needed a tweak?  It’s just one of those things that should take 20 minutes and 4 hours later you’re way into it more than expected, pretty soon the #2 yellow pencil is out, paper and parts and tools everywhere ….stopped way short of that before it absorbed my day 🤪

[Bloo]

Service manuals do usually have the air gap and points gaps, and I used to just set troublesome ones up from scratch. I usually don't tell people to do that, as you have to set the voltage afterward, and it is a pain, and there is really no reason for it to be way off unless someone has been randomly bending stuff in there. Another gotcha is that an aftermarket regulator or newer regulator may not use the same air gap and points gap. Responding too slow like you describe is usually because of extra resistance in the wiring somewhere, but since another regulator cures it, the trouble must be inside that one regulator. If I were working on it, I would look it over real good by following the electrical paths through it, maybe you find a corroded rivet or two somewhere that needs soldering to be electrically sound. I'd also check the air gap, points gap, etc. I'd also make sure it is grounded to the car well.

 

[KAD36]

1 hour ago, Bloo said:

Responding too slow like you describe is usually because of extra resistance in the wiring somewhere,

Good insight, had not thought of it in a “response” context.  Would you lean toward the voltage or current control lagging?

 

I have set troublesome ones up sorta almost from scratch, that’s why my preference is the screw adjusters.  Had a helluva time over and under adjusting the bending tab newer ones for an improvement disproportionate to the time spent putzing with it.  I’ve not gotten any newer ones that work as well as the dried up original that came off the car.

 

Whats the typical high end regulated voltage when cold?  I fiddled with tabs on a newer one to get some level of charge and about 13.8 volts hot (because at 200 deg engine it was not charging when a load was on - but would charge as it cooled off - I think the temp compensation was off as compared to the original) After adjusting it for hot operation it ran up to 16.7 volts cold and I was hesitant to turn any lights on.

 

Apologize for the hijack Chris. 

Edited Sunday at 12:04 AM by KAD36 (see edit history)

[Bloo]

 

9 minutes ago, KAD36 said:

Good insight, had not thought of it in a “response” context.  You think the voltage or current control would be lagging?

Voltage, but the resistance could be in any of the circuits (I think). Current regulation is hardly ever seen doing anything unless the battery is half dead, so your chances of seeing it are slim. Usually flickering is a voltage regulation relay bouncing at a noticeable speed for whatever reason.

[KAD36]

Got it.  Thanks!