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Ammeter/Alternator issue

FY1TopBanana

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The OP’s original question, as I understand, will the ammeter have to be by-passed if an alternator with a higher output capacity is swapped into place of the original spec. alternator with new reproduction wiring and all stock vehicle loads? Nothing about a complete redesign of the original charging system to modern specifications. Alternators don’t “push” anything, if the stock vehicle loads are not changing, there will be NO additional current flow anywhere. If any added loads remain on the alternator side of the ammeter, as originally designed, the ammeter current (battery charging/discharging) is not impacted whatsoever under normal operating conditions.

There is added potential charging current with a higher capacity alternator, as such, the conductors/connections should be sized appropriately for this added potential. Ammeters do not have to be by-passed under these stated conditions. Yes, the original 12ga conductors and Packard bulkhead terminals, and later Molex terminations proved to be under-rated in this circuit, even for the original spec. alternator. We were dealing with overheated bulkhead terminals at the dealers when these cars were relatively new.

Alternators don't push anything? EMF = electromotive force or why is a charge voltage 13.7 - 14.1 for a 12 v battery?
"Electromotive Force is the amount of energy delivered per unit electric charge by a power source such as a generator or a battery (abbreviated E or EMF). As the generator or battery works on the electric charge being transported within itself, energy is changed from one form to another. The device's positive terminal becomes positively charged, while the negative terminal becomes negatively charged. The Electromotive Force is the work done on a unit of electric charge, or the energy gained per unit of electric charge. It is abbreviated E in the international metric system, but it is also known as EMF.
 

Challenger RTA

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Alternators don't push anything? EMF = electromotive force or why is a charge voltage 13.7 - 14.1 for a 12 v battery?
"Electromotive Force is the amount of energy delivered per unit electric charge by a power source such as a generator or a battery (abbreviated E or EMF). As the generator or battery works on the electric charge being transported within itself, energy is changed from one form to another. The device's positive terminal becomes positively charged, while the negative terminal becomes negatively charged. The Electromotive Force is the work done on a unit of electric charge, or the energy gained per unit of electric charge. It is abbreviated E in the international metric system, but it is also known as EMF.
Off hand Is it about 680,000 coulombs per electron.I need to refresh on that!
 
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FY1TopBanana

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I've worked at the milli- and mega-joules end of the technology.
After USAF electronics did spacecraft electrics early career. (Some are still flying!)
So Mopar rewires are for fun..right?
 

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Challenger RTA

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So, after reading up a little bit on an alternator pushing more than around 60 amps, you should bypass the ammeter. // YES NO MAYBE // Is that because it will "fry" the ammeter, fry the wiring, connections inadequate, or will it just peg the meter to the C and keep it there?YES NO AND MAYBE!// Does anyone make an ammeter that looks like the original that will register what an 85 amp alternator puts out? NO! not that I know of.// What gauge wire for an 85 amp output alternator is suitable? I've seen 10 gauge being recommended. I am not running anything demanding a higher load than what was stock (no EFI, electric fuel pump, stereo amp, etc.).That depends on how long of a run. look at the chart // I bought a new under hood wiring kit (from Year One) and looking at the wires coming off the alternator, dang they look thin, which causes me concern after my research here on this site. Your concerns have merit!// I'm real close to initial start up, so I am making sure I don't have a CarBQ. Even if temporary run a 10 or 8ga to the starter + post for piece of mind.

wire-selection-chart.png
 

72RoadRunnerGTX

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Alternators don't push anything? EMF = electromotive force or why is a charge voltage 13.7 - 14.1 for a 12 v battery?
"Electromotive Force is the amount of energy delivered per unit electric charge by a power source such as a generator or a battery (abbreviated E or EMF). As the generator or battery works on the electric charge being transported within itself, energy is changed from one form to another. The device's positive terminal becomes positively charged, while the negative terminal becomes negatively charged. The Electromotive Force is the work done on a unit of electric charge, or the energy gained per unit of electric charge. It is abbreviated E in the international metric system, but it is also known as EMF.
WTF, EMF? Did you not read the OP’s interpretation of “alternator pushing more than around 60 amps” as related to swapping an alternator? Point is, if the voltage (V) and the load (R) remain unchanged, then the resulting current (I) also remains unchanged.

There are some questions on these forums don’t require a full electrical theory dissertation as an answer.
 

Challenger RTA

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Electrical theory dose matter. AC and DC travel through conductors differently. Great minds think alike! Don't blow a fuse!
 

Juan Veldez

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Okay, this got WAY above my pay grade. In addition to what was noted from my first post, let me add that I have brand new wiring from Year One for the front, rear, and under hood areas. I did not purchase new under dash wiring as I thought it looked relatively good. But it is 50 years old now, so maybe that was a bad decision. I'd prefer not to drop another $700 purchasing the new under dash wiring kit, but at the time, there was an undetermined wait time and I would like to finish the car in a month if possible. If cleaning up the connections under the dash with a wire brush and using dielectric grease still leaves the car venerable, then I will wait for the new harness, especially if the new harness comes with upgraded or at least new wiring and connections that spares me from aggravation down the road (no pun intended). If the new wiring kit is nothing more that a duplication of factory original, seems like I still need to modify the setup as a number of you have noted. I know Year One is supposed to be the exclusive provider of the wiring kits, but I believe someone else provides them also - who is that, anyone know?
 

Challenger RTA

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You ask :What gauge wire for an 85 amp output alternator is suitable? Where are you getting that ? The round back is about 45 amps the square back is is 60 amps. correct me if wrong. or are you going for some other upgrade? I think the early 80s pickup, some had 100 amp alt with a stack of shunts.
 
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FY1TopBanana

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WRT the OP --what is the point of the bigger alternator? Not here to argue GTX, only pointing out that the problem a bigger alternator raises has nothing to do with the existing loads remaining unchanged. In the OP case, when they do change as when the battery, asking for charge, results in max output that the equation you point out changes. How much amperage do you want to push through the 12 ga wiring and bulkhead connectors?

In reality we want bigger alternators for bigger loads, and to speed battery charge recovery. That requires a re-thinking of the electric system in a 50 year old car. Only point I'm making. I have a dual Flexalite 3800 cfm cooling fan than can draw 40amps itself - 8 ga home run to fan pwm from the rear battery bus. Mega-cap audio guys like 200 amp alternators as do hydraulic hopper cars. I've wired all types.
 

Challenger RTA

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Okay, this got WAY above my pay grade. In addition to what was noted from my first post, let me add that I have brand new wiring from Year One for the front, rear, and under hood areas. I did not purchase new under dash wiring as I thought it looked relatively good. But it is 50 years old now, so maybe that was a bad decision. I'd prefer not to drop another $700 purchasing the new under dash wiring kit, but at the time, there was an undetermined wait time and I would like to finish the car in a month if possible. If cleaning up the connections under the dash with a wire brush and using dielectric grease still leaves the car venerable, then I will wait for the new harness, especially if the new harness comes with upgraded or at least new wiring and connections that spares me from aggravation down the road (no pun intended). If the new wiring kit is nothing more that a duplication of factory original, seems like I still need to modify the setup as a number of you have noted. I know Year One is supposed to be the exclusive provider of the wiring kits, but I believe someone else provides them also - who is that, anyone know?
The battery and charging circuit is the problem along with the connections. The under dash harness should be fine.just inspect the end for burnt ends or hardness. Both ends all ends! plug for headlight sw, foot dimmer sw, connection on heater.
 
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Juan Veldez

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You ask :What gauge wire for an 85 amp output alternator is suitable? Where are you getting that ? The round back is about 45 amps the square back is is 60 amps. correct me if wrong. or are you going for some other upgrade? I think the early 80s pickup, some had 100 amp alt with a stack of shunts.
This is the alternator installed. Looks like the square back. My concern comes from previous posts about electrical problems others have noted. I probably misunderstood that an alternator that has an increased output from stock can cause a problem by itself. Maybe it was actually due to installing more items from stock that had bigger draws. I'm just trying to do the right thing and not have any electrical problems. I've continually taken 3 steps forward and one step back re-building this car and would prefer that stop now. I really do appreciate everyone's responses - thank you.20220321_123428.jpg
 

FY1TopBanana

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Juan V that Powermaster should have come with a dyno card in the box that shows idle and max output. May be able to id it externally otherwise if you didn't buy it originally.
No worries about the 3 forward and one back progress. That's the Mopar hobby. If we wanted easy we would have gone oval or bowtie.
When Mopars go one step forward and 3 back, been there, you wonder sometimes..
 

Juan Veldez

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Juan V that Powermaster should have come with a dyno card in the box that shows idle and max output. May be able to id it externally otherwise if you didn't buy it originally.
No worries about the 3 forward and one back progress. That's the Mopar hobby. If we wanted easy we would have gone oval or bowtie.
When Mopars go one step forward and 3 back, been there, you wonder sometimes..
I purchased it. The "Proof of Performance" numbers are: 73 Idle / 85 Cruise / 114 Top End.
 

Challenger RTA

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There is a cover for the alt stud get one or find it. Remember the stud is always hot when the battery is hooked up. A short with a wrench or other will destroy the wiring.

Mopar 1964-74 Alternator Hot Wire Insulator​


Mopar 1964-74 Alternator Hot Wire Insulator.jpg
 
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Juan Veldez

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There is a cover for the alt stud get one or find it. Remember the stud is always hot when the battery is hooked up. A short with a wrench or other will destroy the wiring.
I'm looking for those rubber sleeves (or whatever they are called) for my high torque mini starter connections also as I hear it can short out to the block due to proximity. All these "little" things, ugh.
 

FY1TopBanana

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Awesome output. 6 ga charge wire with an inline maxi-fuse (100A) to your start relay batt terminal is my recommendation. I would also do the recommended ammeter bypass, and if you are bringing higher amp loads some distribution and fuse protection strategy.
 

Challenger RTA

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Awesome output. 6 ga charge wire with an inline maxi-fuse (100A) to your start relay batt terminal is my recommendation. I would also do the recommended ammeter bypass, and if you are bringing higher amp loads some distribution and fuse protection strategy.
I agree! And that brings around an other round of issues.
 
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Challenger RTA

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Now for the rest of the story. there a few ways to bypass the ammeter. considering that there is a 6 or 8ga wire to charge the battery. 1,I think the simplest way to bypass is to just move one of the wires over to the other amp gauge stud. The only thing in my opinion is that the current from the alternator is not fused.A fuse-able link right on the alternator. that would resolve that issue. 2,An other way to do it would be remove one wire from the ammeter. Heat tape over or use to feed an acc,other fuse box a voltage gauge. The problem with removing one wire is the is no connection to feed the battery side if there is no charging bypass. 3,This is what I did. An other opinion would be to connect to the starter relay with a fuse-able link or other to feed the alt balk head connector.Cut R6 from splice one and feed to the acc side of fuse box. Then there are two 20-25 amp circuits. I also cut headlight circuit from splice one and fused through fuse box. The only thing that is not fused yet the wiper motor from splice 3. Might piggy back on acc side fuse box or do an inline fuse,or add a small fuse box using one of the disconnected ammeter wires. I can't do that I cut them they were in bad shape! Keep in mind. If in good condition the disconnected ammeter wires can be used to feed other fused circuits. This is What I did or will do and feel comfortable with.your choice if you do it or not. Document fusing and keep in glove box for reference.

20210519_111909.jpg
 
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