Slant Six Forum :: Pegged amp gage has me stumped

For most of your measurements, I agree with the comments about too much voltage drop... but that particular measurement (#A) worries me. I'm assuming you mean "alt power lug to battery ground", yes?

(Are your meters calibrated to each other?)

If "engine off" means "key off", then there shouldn't be ANY current flowing, so battery V should exactly equal alternator output V.

Remember that the total (charging output) circuit is only this: Positive battery terminal - bulkhead connector - ammeter terminal - (guts of meter) - ammeter terminal - bulkhead - alternator post. I would clean ALL of those connections and then try again, though admittedly the bulkhead is the most likely to be corroded after 40 years of zero maintenance.

It's kind of amazing that you're not frying other things and blowing bulbs when the voltage spikes, actually

When testing was conducted yesterday, both meters used same ground point,

Still not clear on just how voltage regulator controls output of alternator. I have a duel field alternator with one field grounded. I do get that the non field terminal reads ignition circuit's voltage, and tells alternator to step up, or reduce output. I need to look up on web to see how this all works. I rather not be a plug and play guy, but rather understand the physics of the thing.

Yup, green kill switch on both of my old cars. I donâ€™t trust them where they often reside in Man Cave under dwellingâ€™s living spaceâ€¦ That is, rather, the basement. LOL Also they provide a real quick way to kill the juice if something starts to smoke.

Digital VOMs mean we worry over a couple of tenths of a volt... mechanics of 40 years ago were AT BEST concerned with 1/2 volt increments.

Where's the big Mopar show in Maine this Saturday?

I think that despite some excellent troubleshooting you are chasing ghosts here.

... the symptom never appeared during testing, which means we never actually saw a reading that was directly attributable to the pegged amp gauge issue.

Check and recheck all the connections for cleanliness and tightness. Then change the VR today and start the car every day this week. If the symptom doesn't re-appear, then the chances are the regulator is to blame.

This is a system with only three "moving parts" (besides a myriad of connections) Voltage Regulator. Alternator. Battery.

After thinking about this as a â€˜three componentâ€™ problem, and the way the problem manifests as if a switch was turned on and off, making problem come and go instantaneously,

Again, this is totally off the wall, but you could throw a 4700uf @ 25vdc cap between the sensing terminal of the regulator and ground... just to see if the situation changed.

Author:	Jeb [ Sun Sep 04, 2011 4:24 pm ]
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I would definitely check that bulkhead connector. My duster had all sorts of weird electrical problems, I was only able to find the cause after the bulkhead connector melted one cold rainy december night. Left me in the MIDDLE of the road on the back side of nowhere with a car that was virtually dead. I would recommend carrying some road flares also. I'm glad I had some in the trunk that night.

Author:	wjajr [ Sun Sep 04, 2011 5:39 pm ]
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Eric, Quote: For most of your measurements, I agree with the comments about too much voltage drop... but that particular measurement (#A) worries me. I'm assuming you mean "alt power lug to battery ground", yes? That is correct. Quote: (Are your meters calibrated to each other?) After checking there is a 0.07 volt difference between the two VOMs. VOM used yesterday to monitor battery terminal voltage read 12.95V tonight, VOM used to monitor alternator power lug to battery negative terminal read 12.88 V tonight when measuring voltage across battery terminals at same time; for a difference between instruments of 0.07 volts. When testing was conducted yesterday, both meters used same ground point, engine side of green kill switch, just because I could easily attach a jumper at that point to reach into cockpit. There is no voltage drop between battery side of green switch, and engine block side of switch, so it electrically the same. Key off: No voltage drop between battery plus terminal and block, head, voltage regulator case, spark control, and alternator case. All reading = 12.95 volts Quote: If "engine off" means "key off", then there shouldn't be ANY current flowing, so battery V should exactly equal alternator output V. It is when same VOM is used to test each device. Quote: Remember that the total (charging output) circuit is only this: Positive battery terminal - bulkhead connector - ammeter terminal - (guts of meter) - ammeter terminal - bulkhead - alternator post. I would clean ALL of those connections and then try again, though admittedly the bulkhead is the most likely to be corroded after 40 years of zero maintenance. New bulkhead connector and brass connectors three years and or 10,000 miles ago Each connector treated with contact enhancement fluid from Radio Shack. Two months ago there was less than a tenth of a volt drop through same circuit described above. At that time I looked for a voltage drop, found a lot at the green switch engine side connection to block ground cable clamp. The rest was a parallel resistance path from tapping high side of ceramic ballast resistor to power electric choke and coil, the same point that feed voltage regulator. This story can be found here. Quote: It's kind of amazing that you're not frying other things and blowing bulbs when the voltage spikes, actually I agree something should have popped. Everything is turned off such as radio, interior lights. The head lights, and electric choke which are now controlled by relays. The brake and back-up lights, as well as all gages are still working. Tomorrow I shall check for voltage drop at bulkhead connector, reinstall old mechanical voltage regulator, and run that for a few days. Still not clear on just how voltage regulator controls output of alternator. I have a duel field alternator with one field grounded. I do get that the non field terminal reads ignition circuit's voltage, and tells alternator to step up, or reduce output. I need to look up on web to see how this all works. I rather not be a plug and play guy, but rather understand the physics of the thing. Yup, green kill switch on both of my old cars. I donâ€™t trust them where they often reside in Man Cave under dwellingâ€™s living spaceâ€¦ That is, rather, the basement. LOL Also they provide a real quick way to kill the juice if something starts to smoke.

Author:	mpgFanatic [ Sun Sep 04, 2011 7:20 pm ]
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Quote: When testing was conducted yesterday, both meters used same ground point, Excellent-- having a common ground reference is really the only way to know that you're comparing apples to apples. Quote: Still not clear on just how voltage regulator controls output of alternator. I have a duel field alternator with one field grounded. I do get that the non field terminal reads ignition circuit's voltage, and tells alternator to step up, or reduce output. I need to look up on web to see how this all works. I rather not be a plug and play guy, but rather understand the physics of the thing. Actually, I think you've got the idea pretty well. The only other notion to keep in mind is understanding where each device "sees" its reference. An external regulator can measure from a point near where the rest of the car is actually using the power. The modern technique of using a one-wire alternator (with an internal regulator) doesn't have that advantage. Speaking of which, one of the more intriguing reads I've come across is this one from a hot rodder who is quite fond of the Chevy electrical system's method of "remote sensing". (Chrysler senses in a similar remote fashion, though not using a big huge obvious splice as a power distribution point.) In particular, I was interested by the system's ability to utilize a much smaller wire diameter (than the Delco engineers would have wanted) without causing undue problems, thus saving weight and cost of copper. A clever way of engineering it to pass the bean counters' demands. Quote: Yup, green kill switch on both of my old cars. I donâ€™t trust them where they often reside in Man Cave under dwellingâ€™s living spaceâ€¦ That is, rather, the basement. LOL Also they provide a real quick way to kill the juice if something starts to smoke. If the engine is sitting still, yes. If it's running, suddenly removing an alternator load could cause problems. Attaching a bright red "stop" switch to the ignition coil wiring has always seemed like a very appropriate idea, for anyone who enjoys tinkering with the hood up... it's been on my to-do list for a long time. - Erik

Author:	Slanted Opinion [ Mon Sep 05, 2011 3:48 am ]
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I think that despite some excellent troubleshooting you are chasing ghosts here. I say that because: 1- You've taken an excellent set of measurements. 2- The symptom never occurred while you were taking these measurements. There are some concerns about the voltage drops... BUT the old girl may have had those drops the day it rolled off the showroom floor. Let's face it, our A-bodied cars had reliable, but not very efficient, electrical systems. Digital VOMs mean we worry over a couple of tenths of a volt... mechanics of 40 years ago were AT BEST concerned with 1/2 volt increments. And STILL... the symptom never appeared during testing, which means we never actually saw a reading that was directly attributable to the pegged amp gauge issue. Check and recheck all the connections for cleanliness and tightness. Then change the VR today and start the car every day this week. If the symptom doesn't re-appear, then the chances are the regulator is to blame. Where's the big Mopar show in Maine this Saturday? - Mac

Author:	wjajr [ Mon Sep 05, 2011 6:21 am ]
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Quote: Digital VOMs mean we worry over a couple of tenths of a volt... mechanics of 40 years ago were AT BEST concerned with 1/2 volt increments. I agree, also I have the same beef with digital speedometers, and clocks; too precise requiring too much brain power to convert to old school analog. â€“ nearest five minutes or Mph is good enough. A swinging needle is by far much easer to glean information from than a bunch of rolling digitsâ€™ for these applacations. For now Iâ€™m going to transplant the old regulator back into the belly of the beast, and keep an eye on things where I just had all this stuff apart a few months ago. Quote: Where's the big Mopar show in Maine this Saturday? Darlings Chrysler on Western Ave., Augusta. Take Rts. 17 & 202 exit off of I-95, head west or to Winthropâ€”canâ€™t recall signage, the show is less than a mile from exit on north side of street. I attended last yearâ€™s show, it was very well run, judges knew their stuff, and the quantity and diversity of cars was excellent. I think if you poke around on Darlingâ€™s web site you can find photos from last year. Iâ€™ll be there with a minimum of one car.

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Author:	mpgFanatic [ Sun Sep 04, 2011 3:56 pm ]
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Author:	mpgFanatic [ Mon Sep 05, 2011 6:54 am ]
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Quote: I think that despite some excellent troubleshooting you are chasing ghosts here. ... the symptom never appeared during testing, which means we never actually saw a reading that was directly attributable to the pegged amp gauge issue. How else does one search for an elusive, intermittent problem? Even if you don't find the direct attribution, you may stumble across a reading that tells you where to look for your ghosts. Yes, mechanics used to be concerned with maybe 1/2 Volt. That is exactly the suggestion someone already made about a drop over the wiring system. No one has insinuated anything about microscopic increments in voltage, with the one exception of verifying that two meters share a calibration. Quote: Check and recheck all the connections for cleanliness and tightness. Then change the VR today and start the car every day this week. If the symptom doesn't re-appear, then the chances are the regulator is to blame. I don't understand why you're chastising all our efforts, then blithely presenting exactly the same conclusion. Well, in a way, I guess that makes one more agreeing diagnosis. - Erik

Author:	Slanted Opinion [ Mon Sep 05, 2011 8:18 am ]
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My sincere apologies if you felt I was chastising your efforts. That was not my intent. Your testing procedures are good, and your thought process is good. What I'm doing is trying to resolve the issue using the KISS method. This is a system with only three "moving parts" (besides a myriad of connections) Voltage Regulator. Alternator. Battery. Sometimes, when you have an incredibly simple system with an mysterious, intermittent problem, the best route to troubleshooting (esp. if you have a deadline, which he does) is to just replace the part and see if the intermittent goes away. It seems like he has already done the "check connections" steps... that leaves one of the three "moving parts", all of which are relatively inexpensive. The voltage drops are interesting, perhaps notable. At the same time, this Dart may run fine for the next 25 years with those voltage drops in place. Think of it this way... if you were paying a garage $80 an hour to troubleshoot this problem, wouldn't you want them to try the most obvious solution first? - Mac

Author:	wjajr [ Mon Sep 05, 2011 2:31 pm ]
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Slanted Opinion: Quote: This is a system with only three "moving parts" (besides a myriad of connections) Voltage Regulator. Alternator. Battery. I had these very three components to an automotive electrical rebuild place to be tested a few months ago. Both regulators were within speck, alternator good, battery was getting plated up, so I purchased a new one. After thinking about this as a â€˜three componentâ€™ problem, and the way the problem manifests as if a switch was turned on and off, making problem come and go instantaneously, it seams reasonable to discount batteryâ€™s contribution as it would either be working correctly, or not working as designed. Alternator could be shorting internally, but with high current flow coming & going, and it having no internal control, I would think it also would be working as designed, or not. Lastly the brain or regulator that controls the output & reads system voltage, the only device capable of switching on & off instantly output of alternator stands a greater chance of malfunctioning in such a way as to cause spikes of current flow. As for connections, I donâ€™t think that any of them are capable of being competent one moment, than incompetent the next as none of them move, generally this spike condition occurs when car is stationary with little vibration to disturb any of these connections. If this problem occurred, say after a General Lee type stream jump, that previous thought would be moot, because a crash landing would introduce some unexpected conditions not in the minds of the designersâ€¦ So as soon as this is posted, the old unit is going back in. Bill

Author:	mpgFanatic [ Mon Sep 05, 2011 4:35 pm ]
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Quote: After thinking about this as a â€˜three componentâ€™ problem, and the way the problem manifests as if a switch was turned on and off, making problem come and go instantaneously, The way you describe that makes me realize there are ignition switch contacts that are part of the circuit to the IGN terminal of the regulator. Food for thought. - Erik

Author:	KBB_of_TMC [ Wed Sep 07, 2011 11:07 am ]
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When I had intermittent charging problems, I finally ran some wires from under the hood to the passenger compartment so I could montor points when the problem occurred. I eventually tracked my problems down to a flaky regulator. I might suggest that you simultaneously monitor the alt's BAT and + battery post. Simple automotive analog voltmeters can had cheaply from Harbor Freight; you don't need great accuracy. If the ammeter goes to +peg and both voltages remain sane or fall, perhaps there's a big intermittent short on the battery side of the ammeter - perhaps inside the starter solenoid or wiring? If both voltage goes very high, you know that it's not a big load causing it and the system is trying to overcharge. If one goes high and the other falls, you know you've got an open in the path. Best of luck.

Author:	Slanted Opinion [ Thu Sep 08, 2011 4:46 am ]
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One of the most vexing things in troubleshooting is having a new part that is defective. It is rare, but it does happen. When it does your mind refuses to believe it, despite what your eyes observe. As a side note... and thinking totally out of the box here... what if a "spike" is coming down the line and throwing the electronic regulator into a tizzy? You've got relays, etc, in this system. Do they have diodes across the coil to absorb the spike generated when they go from energized to de-energized? Again, this is totally off the wall, but you could throw a 4700uf @ 25vdc cap between the sensing terminal of the regulator and ground... just to see if the situation changed. - Mac

Author:	wjajr [ Thu Sep 08, 2011 7:40 am ]
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Mac, Quote: Again, this is totally off the wall, but you could throw a 4700uf @ 25vdc cap between the sensing terminal of the regulator and ground... just to see if the situation changed. I guess I donâ€™t grasp what you are getting at. Do you mean adding a condenser on ground side of relay coil that is powered up when key is on, and not powered when key is off? I have five relays: two that operate convertible top which are intermittent service when dash switch is activated its power taped from fuse block; same for headlight high & low beam relays, activated only when headlight switch is pulled, and lights power from power lug on alternator. This leaves relay powering electric choke, and future o2 sensor which is activated when ignition key is in on position powered by tapping into circuit at high side of Ignition Ballast; this tap shares a common point in circuit with voltage regulator battery terminal. No diodes are employed that I know of. Relays are just simple Bosh 85 86 / 30 87 type. Is there a switched power point less sensitive to voltage regulator, to power choke relay, other than at Ballast Resistor? Bill

Author:	bigslant6fan [ Thu Sep 08, 2011 12:14 pm ]
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Maybe the armature in the alternator is the problem,We all know if the green wire from the regulator-alt. terminal shorts to ground, it will over charge. Maybe the winding is shorted near were the green wire is connected. Maybe the brush holder or insulator is loose or bad. I HAVE seen this problem happen on the blue wire side,and burned up the wiring. EDIT: Disregard the above info,it only applies to the 70-up charging system.

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Author:	wjajr [ Thu Sep 08, 2011 1:37 pm ]
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After several starts with old mechanical regulator, there has been no gage pinning. I have tried starting with a lightly discharged battery & fully charged battery, and gage reacts normally. So at the moment, the discarded new VR 128 or VR1001--- which ever one I have--- took a power. And, I bet it has to do with the malfunctioning (loose) â€œFieldâ€ post. At some point I shall conduct an autopsy on that device and see just what happened internally around the â€œfieldâ€ terminal.