10.4V at the Alternator/choke: what does it mean?

[NukeBass]

I put on a Street Demon carburetor this weekend and in the process rerouted my fuel line (that was fun...) and finally checked the voltage on my electric choke line that was put in place by the shop that restored my car. The reason I was looking at it is because it was a (blue) wire off of the alternator and all of the instructions say don't wire it to the alternator. I checked the source and it appears to be a keyed voltage source, but only measured 10.4V and not 12V like the instructions say. Is this a normal condition off of the alternator or does it indicate other electrical problems somewhere? Will the 10.4V cause problems for the electric choke?

 

[67Dart273]

As usual........

What year make and model is this "car"

What kind of alternator do you have, IE original Mopar, or Denso conversion, what?

What "wire" is it hooked to?

Surely not the big thick output wire........................

Do you have a green field wire? WRONG one!!!

Do you have a blue wire? This "should work" but many of these cars have voltage drop problems. There was just a thread on this.

http://www.forabodiesonly.com/mopar/showthread.php?t=319318

 

[nm9stheham]

Is this 10.4v with the key in RUN but the car not running, or with car running? That will give an idea of how serious the voltage drop is. And it needs to be referenced to the battery voltage. Can you give us the operating situation in more detail and a battery voltage measurement too? In general, 10.4v at indicates some undesirable voltages drops in the wiring.

And the best way to put on the choke is to use the blue wire in the original harness that feeds to the ignition system and to the voltage regulator to activate a relay, and use the relay contacts to feed power to the choke. That will take the current load of the choke off of the switched ignition circuit and reduce any voltage drop and connector heating problems.

As above, what year & model? Is the wiring original or has it been replaced?

 

[NukeBass]

Sorry, I should have been a little more descriptive. The car is currently a 73 340, with the 340 replacing the original /6 a couple of years ago. All of the wiring in the engine compartment is new, but the bulkhead connector is the original one and the alternator is a stock style alternator (not sure brand or anything). I attached pictures of the blue wire at the alternator and at the choke. There's a primary black wire in the alternator, a green wire, and then the blue wires.

I checked the voltage with the key ON and the engine off. I didn't think to check it again once the engine started. I do know the voltage opens the choke since I had to get a battery for my voltmeter and left the key ON for about 5 minutes. It was full open by that point and I had to let it sit before I started it again.

I probably should have waited for this question because the car is back in storage now and I can't get anymore measurements for a while. I'm having a house built and a friend of my father is storing the car and they live a few hours away. I put this new carburetor on and finally remembered to check the voltage, so I got worried I was going to have to rewire the car at some point. Winter projects!

Thanks!

 

[nm9stheham]

If the voltage at the blue wire is dropping, say, 1.5 volts, then the ignition will be getting less voltage, and the voltage regulator will be commanding the alternator to put out more voltage than normal to try to compensate for the lower voltage, and the the electrical system will run at a higher than normal voltage. Plus, the heating at wherever the voltage drop is highest is fairly likely to cause an eventual failure at that point; the extra current in the choke just makes that more of a potential problem.

The drop can be anywhere in the path from the battery to the blue wire, with the blue wire's bulkhead connection, the ignition switch and its connectors, and the fusible link off of the starter relay to its bulkhead connection.