James_Douglas Posted May 23, 2007 Report Share Posted May 23, 2007 Has anyone actually ever had their AMP meter go bad ? I don't mean just stopped working, but start giving erroneous readings ? I re-build my 6 volt alternator with new rectifier, voltage regulator, and brush assemblies. The car is still showing charging problems. Specifically, it seems to take a lot of RPM to get the thing to self energize and then with everything on it just shows directly in the middle of the gauge. No charge, no discharge. When I turn on everything you can see the lights come up when you rev the engine. However, every now and then I can kill the engine with everything on at idle. I don't know what else it could be. It is possible that the alternator windings may be going south, so today I will take the thing in to a shop and have it checked. That said, I am starting to suspect the AMP gauge. James Quote Link to comment Share on other sites More sharing options...
TodFitch Posted May 23, 2007 Report Share Posted May 23, 2007 Does that car use a shunt on the ammeter circuit? I had a couple of newer (60s and 80s) Chrysler products where the ammeter itself was on a shunt circuit so only a portion of the current went through the gauge. This allowed them to use a small wire size to and from the dash and put in a less expensive gauge that did not have to carry a lot of current. On the 82 TC3 the problem was that the connections between the wiring harness and the flex circuit on the back of the dash assembly oxidized raising the resistance of the circuit through the ammeter. Basically when that happened the ammeter would read zero all the time. Cleaning the contacts between the harness and the flex circuit would get the gauge to work again. At least for a while. It was a bad design. At the very least they could have plated the contacts to keep them from oxidizing. Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted May 23, 2007 Report Share Posted May 23, 2007 In checking your amp guage..with the car NOT running, and things like the headlights, blower motor etc on...does the guage indicate a discharge? If so is this a steady reading without fluxiation? If so then the problem may well be in the charging circuit only...check for a good ground on your alternator, clean field connection and if a one wire unit...then maybe have to remove and carry to Auto Zone for testing on the bench...your having to rev it up before anyindication indicates a one wire setup without a tickler... Quote Link to comment Share on other sites More sharing options...
homebrewer Posted May 23, 2007 Report Share Posted May 23, 2007 Tim, I have a one wire 100amp alternator on the350SBC in my 48 P15 and I have the same problem as far as the amp guage showing zero, and no increase in voltage checked at the batt. with a volt meter. If I goose it, the meter shows a charge and the voltage meter reads charging voltage. Once it shows on the amp meter it will run fine all day until I turn it off, then the whole process starts over. Do all one wire alternators operate this way? What is a tickler? And if I add one will it solve my problem? Or should I suspect a bad alternator. Quote Link to comment Share on other sites More sharing options...
De Soto Frank Posted May 23, 2007 Report Share Posted May 23, 2007 James, To the best of my knowledge, all six-volt MoPar in-dash Ammeters are inductive, essentially a brass or copper buss-bar with a terminal stud at each end. The EMF produced by current flowing through said buss acts on the tail-end of the ammeter needle, causing it to deflect appropriately. As long as the pointer pivots aren't binding, and the connections at the studs and buss-bar are tight, these are pretty bullet proof. About the only way to kill one is to try to pull starter current through it. Since a few other six-volt alternator guys have had experiences similar to yours, I wonder if the GM one-wire unit is up to the additional current-load requirements of the six-volt system ? If these things are cooking diodes, perhaps better heat-sinking is needed ? ???? Quote Link to comment Share on other sites More sharing options...
martybose Posted May 23, 2007 Report Share Posted May 23, 2007 Tim, I have a one wire 100amp alternator on the350SBC in my 48 P15 and I have the same problem as far as the amp guage showing zero, and no increase in voltage checked at the batt. with a volt meter. If I goose it, the meter shows a charge and the voltage meter reads charging voltage. Once it shows on the amp meter it will run fine all day until I turn it off, then the whole process starts over. Do all one wire alternators operate this way? What is a tickler? And if I add one will it solve my problem? Or should I suspect a bad alternator. Most alternators that are one wire units are set up so that when the engine is first started you have to reach some RPM above a fast idle before they will start charging. You can get a gizmo from the 5th Avenue Garage that adds a diode-equipped exciter wire to the alternator, then it charges as soon as the engine fires. That said, mine doesn't charge until I've warmed it up for a minute or so and am willing to rev it a little, and it only takes maybe 30 seconds before the current comes down to a "normal" level, so I don't worry about it. Marty Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted May 23, 2007 Report Share Posted May 23, 2007 Tim, I have a one wire 100amp alternator on the350SBC in my 48 P15 and I have the same problem as far as the amp guage showing zero, and no increase in voltage checked at the batt. with a volt meter. If I goose it, the meter shows a charge and the voltage meter reads charging voltage. Once it shows on the amp meter it will run fine all day until I turn it off, then the whole process starts over. Do all one wire alternators operate this way? What is a tickler? And if I add one will it solve my problem? Or should I suspect a bad alternator. I would suspect in your case that the aternator ouput is tied directly back to the battery intself bypassing the ingnition switch and the the amp gauge. Reason for this is that output SHOULD be an 8 gauge wire for 100 amp alt output. They are hooked up this way so as to prevent battery drain should their be an interal fialure in the regulator. These can be connected to output via sense from the ignition but I did not copy any links to this, internet search on "Installing 1 wire GM Alternator" should get you the answer..it is just a two wire pigtail you splice in....I sent this to Don c. one time..he may have earmarked in adn willpsot this link......My alternator of choice will always be the Chrysler dual field with electronic regulator is the reason I did not save this info for myself. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted May 23, 2007 Author Report Share Posted May 23, 2007 Ok, I took it for a drive and here are the symptoms... Engine off, ignition on and all electrical items on and I get a deep discharge on the needle. Say 30 AMPS. After starting it and revving it it up to have it self excite...with everything off but the ignition I get a slight charge at idle. I run it around for about 20 minutes and I get a charge of say 20 AMPS that decreases with time. So I assume it is charging the battery from my multiple starts and having everything previously on. Like I said, after about 15 minutes at road speed it is back down to a slight charge. Now, if I am motoring down the block and I pull over to the side of the road and I turn on everything I get a deep discharge of about 30 AMPS. However, if I take off, the AMP gauge only goes back to about center or a very slight charge. I take this to indicate that the battery is still providing most of the current to run the devices. I should see a 30 AMP positive flow on the AMP gauge. If I pull the battery cable with the engine running at say 1500 RPM with everything on it kills the engine. Still sounds like the alternator to me, unless something has changed in the wiring or the AMP meter while I had the dash out last week for the trans swap wiring. Hummmmmm.... James Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted May 23, 2007 Report Share Posted May 23, 2007 http://mightymo.org/Proj_OneWire.html#Wire%20to%20vehicle http://www.311s.org/tech/electrical/singlewire.html Couple places to get you going..this will show you how to hook itup through the amp gauge/ign sw and use of idiot light if you like... For those that have erractic gauge action on the 1 wire when truning off and on certain loads...please check grounds..be sure you alternator has clean good ground independent of the accessories it is driving... Quote Link to comment Share on other sites More sharing options...
Lou Earle Posted May 23, 2007 Report Share Posted May 23, 2007 what size is your pulley- a large pulley will necessitate a huge rpm surge to energizes the alternator 6 or 12 volt I had this happen on my Chevy powered plym. Change to smaller pulley and also the diode or whatever can be malfunctioning your generator shop can check that but I suspect large pulley Lou Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted May 23, 2007 Author Report Share Posted May 23, 2007 what size is your pulley- a large pulley will necessitate a huge rpm surge to energizes the alternator 6 or 12 volt I had this happen on my Chevy powered plym. Change to smaller pulley and also the diode or whatever can be malfunctioning your generator shop can check that but I suspect large pulley Lou Lou, I have a 2.5 inch pulley. And it was working ok with this pulley so that can not be it. James Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted May 23, 2007 Author Report Share Posted May 23, 2007 http://mightymo.org/Proj_OneWire.html#Wire%20to%20vehiclehttp://www.311s.org/tech/electrical/singlewire.html Couple places to get you going..this will show you how to hook itup through the amp gauge/ign sw and use of idiot light if you like... For those that have erractic gauge action on the 1 wire when truning off and on certain loads...please check grounds..be sure you alternator has clean good ground independent of the accessories it is driving... Tim, The grounds are very very good on this car. In addition to the normal body to engine ground...I even have a #8 wire going from the ground lug on the alternator to clean metal spot on the dash. I will keep hunting. I am off to the alternator shop for them to test my re-build unit. Be back in a couple of hours and will report... Best, James Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted May 23, 2007 Report Share Posted May 23, 2007 Here is how my system works with a twelve volt conversion using a mid 80's GM alternator. Cold start the amp gauge stays at the neutral position even while cranking the engine, As soon as the engine fires the amp gauge stays neutral until around 1200 RPM's. At that speed the alternator excites and kicks in and the amp gauge shows a high charge until the battery is re-charged. Then the amp gauge shows a slight charge. If I turn on the headlights the amp gauge moves very slightly to the charging side. When my electric radiator fan kicks on the amp gauge moves to a heavy charge around 15 amps and stays there until the cooling fan shuts down indicating the engine temperature has dropped below the electronic thermostat setting. These conditions repeate until I turn the engine off. Upon restart this cycle repeats. Before I installed low amperage LED brake lights I could see a slight (quick blip) discharge on the amp gauge each time I hit the brake pedal. I no longer see that with the LED lights. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted May 24, 2007 Author Report Share Posted May 24, 2007 Don, What do you get on the gauge when: 1. Everything on, IGN on, Engine Off. 2. Everything on, Engine Running, at idle. 3. Everything on Engine at 1500 RPM. When engine is off but everything is on, Radio, lights, heater fan, rad fan, spot light, map light, inside (three of them) lights, and brake. Basically everything but the wipers. My AMP gauge gets buried deep past the -35 amp side. I am wondering if I damaged the AMP gauge when I had it out when I took the dash out. Thanks, James Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted May 24, 2007 Report Share Posted May 24, 2007 The indication of a slight charge is normal for an alternator..this is the main advantage the system has over the generator..ability to generate higher current at lower RPM..the basic alternator should have up to 8 amps out at idle.. Don..I see you have not pulled the small plug out of your alternator and run it to 12 volts supply from the ignition so as to charge immediately...the 1200 RPM kick in is not bad once you get used to it... Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted May 27, 2007 Report Share Posted May 27, 2007 Don,What do you get on the gauge when: 1. Everything on, IGN on, Engine Off. 2. Everything on, Engine Running, at idle. 3. Everything on Engine at 1500 RPM. When engine is off but everything is on, Radio, lights, heater fan, rad fan, spot light, map light, inside (three of them) lights, and brake. Basically everything but the wipers. My AMP gauge gets buried deep past the -35 amp side. I am wondering if I damaged the AMP gauge when I had it out when I took the dash out. Thanks, James James; I am away from my car until the 8th of June. But I believe (if my memory brain cells are any good) that I do not get a full discharge with everything energised and the engine not running. With the engine running and everything energised I show a charge around mid way on the amp gauge. However remember I am running 12 volts and my amp readings will be halved compared to a 6 volt application. Don..I see you have not pulled the small plug out of your alternator and run it to 12 volts supply from the ignition so as to charge immediately...the 1200 RPM kick in is not bad once you get used to it... Tim; You are correct I have not made that change. I am used to goosing the alternator to excite it (did I say that right) Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted May 27, 2007 Report Share Posted May 27, 2007 James, I do not know the amount of accessories you are running...and to damage the meter..as long as that sucker returns to "zero" the item should not be damaged, in reality the buss bar that induces the reading is quite heavy...you can use a millohm meter and read your meter shunt and equate that with lenght of wire per the wire resistance scale found on many web sites and split your current reading. I intend to parallel another stock meter with mine for same effect with the second one out of sight behind the dash. If you have access to a good meter and shunt you can read the true draw/charge rate. Most hand held meters only are good to 2 Amp and with even better ones limited to 20AMP...an inductive clip on with a 1 millivolt output per amp will allow good reading on a hand held meter way in the hundreds of amps..or either a good Amprobe brand clipon that is AC/DC these are accuratel enough..an AC repairman should have one if you know someone in the business..as this is a must tool for charging units to the RLA. Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted May 27, 2007 Report Share Posted May 27, 2007 a good Amprobe brand clipon that is AC/DC these are accuratel enough.. Tim; I have a clamp on digital approbe that I have not had out of the toolbox for a couple of years. I will check my charg/discharge rate with it when I return home. I should be able to check it right at the battery cable as collectively everything starts and ends there. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted May 28, 2007 Author Report Share Posted May 28, 2007 Tim, The really odd thing is having everything on and not having the AMP gauge show hardly any positive flow. By every thing I mean: 1. Headlights, tail, brake, turn 2. Spot Light 3. Duel heaters (2 motors) 4. Wipers 5. Map light 6. Interior Lights (3) 7. AM transmitter & XM receiver 8. Electric Radiator fan. 9. Engine coil. With all this stuff on, I should see a pretty good positive swing of the needle on the AMP gauge. All I get is a a slight, say 1/6 to 1/8" defection to the right of the needle. The very odd thing is that when I first start up the car with only the coil running, I get a deflection of about 15 to 20 AMP like it is charged the battery back up. This lasts like 10 minutes like it should then slowly drops to zero. This is driving me nuts. I have a high end fluke tester with their best DC clamp that is good to DC 400 AMPs. When I check the current at the output of the alternator is reads something like 30 APMs with everything on. I can not get it around the wire in the dash as it is too tight. The bottom line is that the Fluke readings do not match with the AMP meter. I have a NOS AMP meter on the way. I will stick it in when it arrives and see what, if any, difference it makes. James Quote Link to comment Share on other sites More sharing options...
TodFitch Posted May 28, 2007 Report Share Posted May 28, 2007 If I am reading this right: 1) You showed a negative 30 or so amps on the dash gauge with the engine off and all the lights and accessories on. 2) With the engine on and the alternator tickled so it is working you show zero (or close to it) with all the lights and accessories on but you show 30 amps at the alternator with your Fluke meter. This sounds right to me. At least on all the cars I have ever had the loads are on the alternator/generator side of the dash gauge. So the 30 amps the being produced by the alternator and used by the lights and accessories simply is not being run through the dash ammeter. Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted May 28, 2007 Report Share Posted May 28, 2007 James; What reading do you get with the clamp on connected to the battery cable? Try that with the same test controls ie everything on engine running and engine off. I would think you would get a more actual reading from the battery cable. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted May 28, 2007 Author Report Share Posted May 28, 2007 Tod, I agree. The question is HOW ? I don't understand how the current can be flowing to all the accessories and not show up on the gauge. I know I am missing something, probable that 1/2 of my brain I killed in College. James Quote Link to comment Share on other sites More sharing options...
TodFitch Posted May 28, 2007 Report Share Posted May 28, 2007 I've attached a vastly simplified wiring diagram that excludes fuses, switches, starting circuit, etc. Basically the 30 amps that your alternator is putting out is going into the junction on the right side of the ammeter on the diagram. And all of it is going out to the lights, accessories, etc. So none of it is going to the battery. DonC suggested that you measure on the battery cable as being more a more suitable place to check the ammeter. That is sound because the ammeter only shows the current on the leg to the battery. The exception to this is the starting circuit. To put large enough cables and beefy enough ammeter to show the starting current is not feasible. So the high current portions of the starting circuit are on the battery side of the ammeter. Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted May 28, 2007 Report Share Posted May 28, 2007 I am thinking like I said in the beginning of this thread...it has been connected directly to the battery being a one wire and he is by passing the amp gauge..only a portion of his current is flowing through the gauge.. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted May 29, 2007 Author Report Share Posted May 29, 2007 I am thinking like I said in the beginning of this thread...it has been connected directly to the battery being a one wire and he is by passing the amp gauge..only a portion of his current is flowing through the gauge.. Tim, This NOT correct. I have the one wire connect directly to the original black wire that used to attach to the BAT terminal on the original voltage regulator. The other end of that wire goes directly to the AMP meter. Tod & Don, While running I attached my Fluke tester with the DC clamp on the single wire coming off of the alternator. With everything (no wipers, brake or turn on) on I showed about 27 AMP's. I then switched the clamp to check both sides of the mail battery cables and it showed about the same. The dash AMP gauge was showing a very slight a positive charge. I shut the thing down for 5 minutes and left all accessories on. I then shut them off and started the car. The dash gauge showed a 20 AMP positive charge as did the alternator and the 2 battery cables. I am starting to wonder if something is cross-wired and acting to "push back" some current flow but doing so without overheating or shorting.... James Quote Link to comment Share on other sites More sharing options...
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