Originally Posted by Moparteacher
Originally Posted by Sniper
Originally Posted by RealWing


An alternator will never generate more current than is needed by the demands of the electrical system


This is incorrect. If you full field an alternator, like the OP apparently did, it will put out maximum output regardless of load.

What controls the output of the alternator is the regulator and in the case of this setup there is no regulator and the alternator is hard wired to provide maximum output.

I once had a regulator fail on my and full field the alternator. Blew the over pressure caps off my Optima.


The statement " An alternator will never generate more current than is needed by the demands of the electrical system" is correct.
The regulator regulates voltage, not current. Current is the product of Voltage and resistance. The misunderstanding here is semantics.

CURRENT IS THE RESULT OF (Voltage level and resistance)
Assuming the circuit resistance total (Rt) is fixed, then current will rise and fall as voltage rises and falls. Voltage goes up=current goes up. Voltage goes down=current goes down.
Now, assuming voltage if fixed, current will rise and fall as Rt falls and rises. Resistance goes down=current goes up. Resistance goes up=current goes down.
The regulator regulates the duty cycle of the field from monitoring the voltage. If voltage is low then the regulator will increase the duty cycle of the field (more on-percentage, less off-percentage). If voltage output is high then the regulator decreases the duty cycle of the field.

Regardless, the amount of current that moves is directly controlled by the resistance in the circuit and the electrical pressure ie. Voltage.
E= Electromotive Force/measured in Volts
I=Intensity/Current/measured in Amps
R=Resistance/measured in Ohms

E=IxR (Voltage = Amps times Resistance)
I=E/R (Amps =Voltage divided by resistance)
R=E/I (Resistance = Voltage divided by Amps)

Ohms Law.


What happens to a full fielded alternator?

It goes to max output regardless of load.

I do not misunderstand the semantics, I fully and completely understand the relationship between voltage, current and resistance. It's been my job since 1985.

What you fail to consider is that the regulator measures the load and controls the output of the alternator. So when an alternator is full fielded, as in the OP's test or with a failed regulator, the alternator is being told to go to maximum and it does.

Don't believe it, go full field one and see. Go measure the voltage, measure the current then come back and tell us what the real world tells us about your theoretical one.

Your discussion above is about how the charging system is supposed to work, that is NOT what we are talking about. We are talking about how the OP has set up his test.