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1 Cons are the internal regulator is sensing the output voltage at the alternator terminal, not the battery. With a one wire you just want a good low resistance connection to the battery.
3-wire (external regulator) as installed on our old muscle cars really is not any better.
2 The external regulator senses the voltage of the engine compartment wiring harness which can have a good amount of resistance to the battery.
3 Most of the newer cars and trucks use the 3-wire setup because the computer can directly monitor battery voltage and both air temperature and battery temperature and set the best alternator output voltage to maximize battery life.



1 are you really sure about that statement, and if so, please explain how the way the regulator is wired to make it different in that way.

2 i agree

3 pleas explain how a 3 wire regulator helps the computer to measure battery temperature and air temperature on a newer vehicle. i don't doubt the computer can do those things, but i doubt it's because of the 3 wires on the regulator. regardless of the type of regulator used, it will measure battery voltage, provided a properly sized cable is used on nthe 1 wire type from the battery to the alternator. besides that, the 1 wire does take the possibilty of extra resistance in the wiring harness out of the equation compared to the 3 wire setup. please explain how i'm wrong on that. i'm always willing to learn something new if you have some factual data to share.



1. Because the 1-wire alternator only has an output connection, the internal regulator has to sample the voltage at the alternator output to control the alternators output voltage. Because the alternator heats up when generating power, and has a cooling fan blowing air through the alternator to cool it, the temperature compensation of the internal regulator is not very good. Again, this is not a really big deal, you just may not get the longest life out of your battery.

3. The 3-wire alternator does not sense anything, it just has access to the field connections so the regulator can control the alternator outout. For maximum battery life, the battery needs to be charged at different rates depending on the battery voltage and the battery temperature. Our muscle car regulators have some simple temperature compensation, but it senses the air temperature as an estimate of battery temp, but th e battery will heat up as it is being charged, that us why several new cars have a thermal sensor for the battery. Another problem with the stock muscle car regulator is the battery voltage is sensed after going through a fuseable link, bulk head connectors, ammeter, and ignition switch so there can be a good difference between the ignition wiring voltage and the voltage reaching the battery terminals.

And yes, I am an electrical engineer, but I work for an aerospace company.