Ammeter General Questions

[Bullitt-]

I cannot really leave Y (Dark Blue) as is because the new alternator has no field brushes--it's a 1-wire alternator.

Sure you can...just leave wires off the alternator connection (cause there's no place to plug it), you could even remove the regulator, but leave the ignition wiring as-is.

[jforest1]

Okay, so I went through all the wiring last night to confirm the diagram against reality.  Here's the new one:


Tonight, I'll be putting in the fusible links and testing the Ammeter bypass (represented above W and and emboldened wire reroutes) out with the old 3-wire alternator.

Assuming everything is copesetic, I'll move on to the alternator upgrade (from 3-wire 60amp to 1-wire 200amp).  So the question remains what I do with X/Y coming off the 3-wire alternator field brushes.

Sure you can...just leave wires off the alternator connection (cause there's no place to plug it), you could even remove the regulator, but leave the ignition wiring as-is.

Perhaps I'm misunderstanding what the purpose of connecting the field brushes to the to the carb solenoid, electronic ignition control, fuses, and ignition ballast is...

What is the purpose of the field brush wires going through those other systems?  Is it providing them with power or does the wire serve some other function?   I have semi-educated guesses, but don't know.

JF

[Bullitt-]

Perhaps I'm misunderstanding what the purpose of connecting the field brushes to the to the carb solenoid, electronic ignition control, fuses, and ignition ballast is...

What is the purpose of the field brush wires going through those other systems?  Is it providing them with power or does the wire serve some other function?   I have semi-educated guesses, but don't know.

JF

I believe that the explanation is the Blue wire Y is just + power supply to all of the above mentioned while it is the Green wire X that actually regulates the OE alternator. We know this from the test procedure for alternators is to disconnect the Green wire & jump from the terminal on the alt. to ground to fully energize.       Clear as Mud? 

[jforest1]

I believe that the explanation is the Blue wire Y is just + power supply to all of the above mentioned while it is the Green wire X that actually regulates the OE alternator. We know this from the test procedure for alternators is to disconnect the Green wire & jump from the terminal on the alt. to ground to fully energize.       Clear as Mud?

Hmmm...sort of. 

Modern automotive alternators have a voltage regulator built into them. The voltage regulator operates by modulating the small field current in order to produce a constant voltage at the stator output. The field current is much smaller than the output current of the alternator; for example, a 70 A alternator may need only 2 A of field current. The field current is supplied to the rotor windings by slip rings and brushes. The low current and relatively smooth slip rings ensure greater reliability and longer life than that obtained by a DC generator with its commutator and higher current being passed through its brushes.

...

The field windings are initially supplied via the ignition switch and charge warning light, which is why the light is on when the ignition is on but the engine is not running. Once the engine is running and the alternator is generating, a diode feeds the field current from the alternator main output, thus equalizing the voltage across the warning light which goes off. The wire supplying the field current is often referred to as the "exciter" wire. The drawback of this arrangement is that if the warning light fails or the "exciter" wire is disconnected, no excitation current reaches the alternator field windings and so the alternator, due to low residual magnetism in the rotor, will not generate any power. However, some alternators will self-excite when the engine is revved to a certain speed. Also, some warning light circuits are equipped with a resistor in parallel with the warning light that will permit excitation current to flow even if the warning light fails. The driver should check that the warning light is on when the engine is stopped; otherwise, there might not be any indication of a failure of the alternator drive belt which normally also drives the cooling water pump.

So the blue wire is supplying the field windings with power.  This also is consistent with my experience that grounding the blue wire to the alternator body will fry it (crumbled insulative washer on the field brush).

So you are proposing the cut represented by U, yes?


JF

[Bullitt-]

Cut?....For the sake of the future  of the car I would just unplug & zip tie out of the way. 

[jforest1]

  

As in cut the electrical connection.  So does that course of action sound right -- the proposed disconnects?

I just confirmed the ammeter bypass is now functioning.   Now it's time to get the new alternator bracket into action.

JF

[Bullitt-]

 

As in cut the electrical connection.  So does that course of action sound right -- the proposed disconnects?.

JF

If I understand correctly that the 1-wire alternator your going with only needs the main feed from the alt. to the battery and nothing else then yes.

[jforest1]

As always, thank you Bullitt-.  I'll try this out once I get my alternator mounting issues sorted...

JF

[ShelbyDogg]

I have a feeling that the one wire alternator will give you problems later. Youare not getting the reference voltage off of the 12v at the switch like the voltage regulator was meant to see. The one wire alts are more for racing.  Mad Electrical should have a section on not using these. Just go back and look for it.

As far as running a voltmeter instead of the amp meter, I have it in my resto thread, but I'll paste it here. I use a volt gauge out of a late model Dodge van. The junk yard are full of them and I found enough to do all of my cars. You hook it to th HOT-INPUT terminal on the cluster 5v regulator. Each line reads 2v.

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Before it fits it will have to bet trimmed down and a hole drilled.














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[jforest1]

I have a feeling that the one wire alternator will give you problems later. Youare not getting the reference voltage off of the 12v at the switch like the voltage regulator was meant to see. The one wire alts are more for racing.  Mad Electrical should have a section on not using these. Just go back and look for it.

The switch?  Do you mean the starter relay? 

I've read all of Mad electrical articles (some twice).  I tried to order from them their book among other things but their phone number seems to be disconnected.  Anybody that has their contact info if they are still in business, please let me know!

[ShelbyDogg]

Your alternator and the voltage regulator get it's power from the blue wire that comes from the ignition switch. That is where it gets it's reference voltage from to determine how much voltage to pump out after getting past the resistance in the wiring and connectors. When you use a one wire alternator, you get a ref voltage from the battery and not from the inside where the loads are.

Did you find any articles on not using a one-wire alternator yet?