BYPASS the AMMETER? (1969 A12)

Electrical & Ignition

  1. RJRENTON

    RJRENTON FBBO Gold Member FBBO Gold Member

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    The panel mounter ammeter, sometimes labeled ALTERNATOR, is an instrument that measures quantitatively, the amount of energy the system is producing (charging) or consuming (discharging) by having the system's energy flow through the device. The foregoing statement above is naive and incorrect. The alternator produces power both voltage and current to supply thr vehicle's needs. If the system's rnergy requirements exceed the demand of the alternator, the balance of the energy will be supplied by the battery.
    The deficiencies of the Mopar bulkhead connections is well documented, but to abandon the origional ammeter (or alternator labeled indtrument) for the sake of a voltmeter, is, in my opinion, not worthwhile to consider. Perhaps, the owner should consider up grading the wiring and the connections to and from the existing ammeter, including the connections to the actual device, to eliminate any potential connection abnormalities and corrosion that may be present.
    The ongoing issues of system voltage vs system amperage measurement methods is a personal decision. Voltage measurement indicates that the system's alternator and battery are functioning and are "healthy" but NOT how much energy is being consumed or produced by the alternator and/or battery.
    If the owner has added addition energy consuming devices, albeit cooling fans, auxiliary lighting or sound systems, these addition loads must be taken into account in what the alternator must supply and how much additional current must be taken into account that will pass thru the bulkhead connectors and ammeter (alternator instrument). Unless these addition loads are accounted for, a parallel, relay controlled, individually protected circuits must be considered, sourced at the heavy duty battery connection at the starter motor, not at the output stud of the alternator. Just my opinion of course.
    BOB RENTON
     
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    • Mike67

      Mike67 FBBO Gold Member FBBO Gold Member

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      Simple question, do you want all of your cars load running through that 50 year old gauge? Take into consideration that amperage and resistance are directly proportionate. Resistance is raised by corrosion, thermal expansion, oxidation and tension of the connectors/terminations. If you feel every termination is sound and does not exhibit any of those characteristics go for it...I doubt it though being 50+yo.
      A voltmeter will tell you if your charging system is working simply by watching how fa/low your battery discharges.
      Me, I'm playing it safe and running a voltmeter.
       
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      • 72RoadrunnerGTX

        72RoadrunnerGTX FBBO Gold Member FBBO Gold Member

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        All the vehicle loads don’t run through the ammeter normally, only the battery charge/discharge current. I have no problem running these 50-year ammeters with correctly maintained connections, insulators, wiring, and a correctly sized alternator. I would never power up a 50-year car without going through all wiring/connections related to the charging system, including the close inspection of the ammeter connections and insulators. By-passing the bulkhead connectors in the charging system is a must. A voltmeter provides no more information than a simple idiot light.
         
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        • 72RoadrunnerGTX

          72RoadrunnerGTX FBBO Gold Member FBBO Gold Member

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          This opinion is incorrect, on a vehicle equipped with a battery ammeter, all vehicle loads must be on the alternator side of the ammeter or it defeats the purpose of the battery ammeter, as are all existing factory loads. If additional loads are added, the alternator output capacity needs to be increased and corresponding wire up-sizing for total vehicle loads. No additional loads should be added to the battery side (starter stud).
           
          Last edited: Jul 21, 2020
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          • 440+6

            440+6 FBBO Gold Member FBBO Gold Member

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            This whole ammeter thing is nothing but Mass histeria started by who knows who, I've never heard of a Mopar burning down to the ground because of it. And because you guys saw one picture somewhere or somebody told you all of a sudden it's dangerous, that's ridiculous you should all just play it safe and leave your car at home and not even drive it
             
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            • Nacho-RT74

              Nacho-RT74 FBBO Gold Member FBBO Gold Member

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              Don’t drive on a device with a tank full of a flamable product which needs to be ignited to be moved, and working in parallel to an electrical system what could make it explode anytime! THAT’S DANGEROUS!

              please comeback to the chariots with horses! Is safer!

              a 15k or maybe 45K Volts device is sat side by side to the gas line on engine!
               
              Last edited: Jul 22, 2020
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              • Nacho-RT74

                Nacho-RT74 FBBO Gold Member FBBO Gold Member

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                well, you are running on a 50 years car where everybody pays attention to every aspect of the car when fixing/restoring BUT electrical. Everybody refresh engines, brakes, suspension, but... ELECTRICAL?

                so, yes! I run a 50 YO ammeter because i paid attention on all the aspects on the car including electricals!

                if your brake pads get worn you replace them... right?

                if a terminal gets corroed... replace it! (Or restore )

                is just about the same!!!!!

                most of our cars are still runnin on factory electrical systems! THEY MUST BE GOOD AND STILL FAITHFULL even still with all abuses from owners along the years!
                 
                Last edited: Jul 22, 2020
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                • WM23M9

                  WM23M9 FBBO Gold Member FBBO Gold Member

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                  Wow.. Looking at the diagrams, it looks like a LOT of the dash wiring, acessory lights etc come from the AMMETER? Also seeing now that these giagrams are NOT 100% accurate to all cars, the colors etc on mine (69 A12) are closer to a DART.
                  Does anyone have those "Stacked" connectors from the fuse box? They look OEM, but have no clue now. There WERE areound 5 PINK or YELLOW additional light wires attatched to fuse block. Ive seen this on many 67-73 Chryslers. But there is NO infinite wisdom on where they go to or from... Dunno what I'll do with the Ammeter. I saw from someone, replacing a factory 55 AMP alternator with a 70-90 amp replacement can FRY things as well.. Mopar Wiring.. lol
                   
                • beanhead

                  beanhead Well-Known Member

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                  Call http://www.delmarwire.com/ and tell him what you need. I've gotten those fuse block terminals and other goodies from him in the past. The terminals are OEM. Many of those 'mystery wires' are not shown on the main wiring diagrams that are common on mymopar.com, they are on the "instrument panel accessory" diagram page and must be downloaded as the full set (if available.)
                  Here's the 1968 diagram for example-
                  upload_2020-7-22_8-13-51.png
                   
                  Last edited: Jul 22, 2020
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                  • RJRENTON

                    RJRENTON FBBO Gold Member FBBO Gold Member

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                    Sir,
                    Are you an electrical engineer? Your premise is totally incorrect....there is no such device as a "battery ammeter". An ammeter simply measures current flow either from the source or to the source, via an internal shunt or an external shunt. The shunt provides a fixed resistance, when current flows thru this fixed resistance, a voltage drop occurs. This voltage drop measured across the shunt, is in milli-volts which is calibrated to display amperage on the display flowing either positive, charging or negative, indicating discharging.
                    IF, you look at the source connection of the "fusable link" all of the systems current flows thru this connection EXCEPT for the starter motor's armature current, which includes starter motor solenoid and starter relay. If additional accessory devices are sourced at the alternator's output stud, the dash mounted alternator gauge (ammeter) will not realize this additional load, so how would the operator know if adequate current is being supplied to these accessories? Answer....you do not.
                    The second question is why not source for the additional accessories at the battery connection at the starter motor? Please state your reason(s). The additional loads imposed on the system by these accessories, will be visualized as the required current, will appear as additional load the alternator will need to supply thru the battery charging circuit. If the system is operating normally, a volt meter (gauge) will read the nominal 14.5 volts. Only, if the alternator cannot supply the necessary current the system needs, will the system voltage drop, indicating the current being supplied is coming from the battery.
                    FYI....I am a Registered Electrical Engineer....
                    BOB RENTON
                     
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                    • super-bee_ski

                      super-bee_ski FBBO Gold Member FBBO Gold Member

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                      Thank you for the info.
                      I'll refrain, as did many others on this forum.
                      Not getting pissy with anyone...not my style.
                      But, there is a defect in the design and many have had their cars melt down unbeknownst to them as it typically happens when you are not with the car.
                      Again, take a POLL...
                      99.999 % on this Forum and other Forums have accomplished the MOD.
                      In my life I practice "Better to be safe than sorry"
                      Thanks for your opinions and I can also express mine.

                      :thumbsup:
                       
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                      • super-bee_ski

                        super-bee_ski FBBO Gold Member FBBO Gold Member

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                        Hilarious Nacho-RT74...I LOVE your Style!
                        Great comeback!

                        :thumbsup:
                         
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                        • 72RoadrunnerGTX

                          72RoadrunnerGTX FBBO Gold Member FBBO Gold Member

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                          That is not the purpose of the ammeter used in Chrysler products of the time. It is there to provide real time info on the charge/discharge state of the battery only, nothing else. Ammeters used for this purpose are commonly referred to as “battery ammeters” in the automotive industry. If it’s discharging while running, the loads are exceeding the alternator output at that time. It will not, should not, gauge or register any operating loads. Again, on a vehicle running a factory style ammeter, not a volt meter conversion, any loads added to the battery side of the ammeter will register as a charge current and can/will exceed the design limits of the ammeter and related circuit conductors/connections.

                          Your description of the inner workings of the Chrysler specific ammeter is inaccurate as well.

                          I’m not going to get into a pissing match with you, I was raised by an EE, am a certified master automotive tech for 45+ years, including a good portion of that time at Chrysler dealers.


                          From another thread here a while back; Ok, time to go back to school, jump ahead to 12:10 for the answer to today's question.
                           
                          Last edited: Jul 22, 2020
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                          • Nacho-RT74

                            Nacho-RT74 FBBO Gold Member FBBO Gold Member

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                            NO... everything doesn't come from ammeter, but from ALTERNATOR

                            ammeter doesn feed... batt and alt do... the correct is get everything feeded from alt and get an alt able to do it

                            false... in average, everything is the same. Some differences about equipment, but all Mopars work the same and use to be color coded the same

                            no, you can get a 500 amps alternator, and you won't fry anything. Amperage is requested by the car, not given for free by the alt. If your car requirements is 50 amps, a 500 amps alt will feed just 50 amps with an ammeter right on center, neither charge or discharge. If your alt just gives 30 amps, the rest 20 amps will be given by the batt to source all the 50 amps... then you get discharge.

                            you feed your 100-150 amps starter motor with the same batt you feed a .5 watts bulb on cluster or 21 watts bulb dome light and you don't burn anything.

                            read and learn ;) try to understand the system
                             
                            Last edited: Jul 22, 2020
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                            • Nacho-RT74

                              Nacho-RT74 FBBO Gold Member FBBO Gold Member

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                              Bob, we are agree on what an ammeter is ( internal or external shunt ) HOWEVER on the way the ammeter is disposed on the cars system ( not just Mopars but any other brand back in the days ), the ammeter will measure just what comes and go from/to batt. So it is esentially a Battery ammeter. If you disconect the battery with engine running, and supposing it won't stall because alternator is enough and is safe for the system, you will miss the ammeter reading, because ammeter won't read the loads from/to batt.

                              aside this, you CAN'T get a discharge from a system where is not somekind of accumulator. The alternator is not an accumulator, so...

                              The car ammeters are from - to 0 then to +... a regular ammeter doesn't read negative mesurements, because just reads one sense.

                              and about why not source accesories from batt?

                              easy, because alternator will feed that load throught the ammeter, and will be read as a charge which is not, but is sourcing that accesory load. That's an unnecesary stress to all the system. If you source from alt, and alt is enough to source, the ammeter reading will be zero/center.
                               
                              Last edited: Jul 22, 2020
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                              • Nacho-RT74

                                Nacho-RT74 FBBO Gold Member FBBO Gold Member

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                                Poll based on ppl with knowledgement, or based on what they think is correct without know what they talk about, but just repeating what they read without understand how it works ?

                                :lol:

                                90% of that 80% ( is not 99.99% is a bit less, maybe closer to 80% LOL ) doesn't know how the charging system works or even what it means the ammeter readings.
                                 
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                                • WM23M9

                                  WM23M9 FBBO Gold Member FBBO Gold Member

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                                  Wow, I studied auto electeonics at a local Community College back in 2004, it got super hard to follow with today's cars.. OBD2 etc. Its not hard to understand, some students had no clue! I quit working on em when all the sensors became too much.
                                  I'm curious to as if the AMMETER in the dash of a "Rallye Guage Cluster" is a problem iyself? Prone to failure of its compoments used to make the guage itself? Or if accessories are THE PROBLEM? I've personally never seen or had wiring melt or burn when I drove a 67-74 Chrysler, but I have had many with the "C16 BLK" wire from Alt to Guage melted either when I got the car, or as in this case, its been melted for years. Wasn't there once a "Lights On Warning" buzzer that was also a SAFETY RELAY? People got irritated with, and just yanked the pigtail to silence that buzzing? Which maybe led to OVERHEATING of the dash harness? This is where Ive never found the "Cause" of why lights etc stopped working! So when I was a kid, had to wire in a switch to have tail lights or dash lights (73 Challenger). I have this NEW "M&H" harness all installed in the dash, been studying these INNACURATELY coded wires that appear to more closely resemble that of a 69 DART!
                                  Wondering also since the A12s were so few, if they at Chrysler never copied the Actual wiring for a "Six Pack" no ashtray, map light or other accessories? In these books, they don't apply to a certain car, looks more like "Your Car may be a MIX of these Diagrams" situation now.
                                  Hell, I'm wondering if I should even put the guage cluster back in now! LoL
                                  Thanks!! A bunch! IMG_159543965972F.jpg
                                   
                                • Nacho-RT74

                                  Nacho-RT74 FBBO Gold Member FBBO Gold Member

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                                  @WM23M9

                                  just read the link I posted from dodgecharger.com. Is a crude english thread, I know, it was written by me looong time ago, where my english was worst than now LOL ( now is just a bit better ), but it got diagrams I made about how it works and the reason of the melting failures. And even better, how to solve it still keeping the ammeter and being safe
                                   
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                                  • WM23M9

                                    WM23M9 FBBO Gold Member FBBO Gold Member

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                                    New DIMMER switch, Circuit board and voltage limiter, this is it now. Would you trust it? Has anyone else replaced this much and had SUCCESS? 15954441065036091865030786846780.jpg
                                    I may be the first?
                                     
                                  • WM23M9

                                    WM23M9 FBBO Gold Member FBBO Gold Member

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                                    Ah! Very good.
                                    Yeah, mine has improved also over 50 years.. lol
                                     
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