The "battery" terminal wire is
from the alternator.
I dont have the 65 Dart FSM open right now but if its 12 SAE then this will be close.
Might have been SAE 10 gage. Only the heavy duty options got 8 gage.
View attachment 1716376078
I don't think there is more the 7' from the alternator to the main splice. So maybe 4-5' in the engine bay.
30 amps is a nice round number that should cover everything on plus a few amps recharging or for brake lights.
3% Voltage drop seems to the standard.
One wire is not fully true. At some point it gets bundled in with some otehr wires but thye are not carrying much current.
The '65 cars have a ring terminal connection at the firewall. Theyt should be more secure and more copper mass, so less likely to heat up than the push ons (Packard 56/58). But they are exposed to heat and moisture. We've seen examples where they do get melted. Nothing is 100% perfect.
I don't know the temperature rating of the OEM SAE engine compartment wire. Automotive primary insulation wire is usually lower rated - fine in the rest of the car.
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Measuring max current in the alternator output wire.
Personally I would not stress the wire and terminals like that.
My interest would be in how your alternator compares to factory spec alternators. That's a test at 1250 rpm, controlling the voltage to 15 V. It can be measured at the load (carbon pile) attached to the battery, or at the alternator output. When measured at the battery, the spec excludes power going to the ignition and field.
Another useful measurement that can be done with the clamp meter is to bring the rpm to 1250, and then measure output V and current with various accessories on, such as heater fan and lights, etc. If the Voltage stays above 14 and the ammeter shows the battery isn't discharging, then the alternator is capabale of handling the car's needs.
You can also see what the alternator can produce at slow idle.
All that said, my comment earlier was about field circuit draw, not output. Its supposed to byes e 2-3 amps.