RESOURCES:

Since the early 1900s, the automobile has been equipped with a generator to provide power for the operation of the vehicle and to maintain the charge in the battery. They have been a some what dependable source of electrical power which would keep up with the current demands of the time. As time marched on, the demands for more electrical power steadily increased, as current day creature comforts were designed and installed on the automotive assembly line. In the mid 1960s the demands for more current was becoming so great that the automobile manufacturers switched from the traditional generator to the new alternator.

The alternator had the ability to produce more current at lower engine rpm’s as well as higher current output overall compared to the generator. Another advantage of the alternator was the fact it had brushes that ran on a smooth surface internally compared to the rough armature of the generator which could double or triple brush life.

The progression of the alternators has been from a small 35 amp output unit with an external regulator to the current day internally regulated unit with nearly unlimited output. A typical unit on a classic vehicle now is about 100 amps output and capable of nearly all its output at idle speed. Another feature that is becoming very popular  is the “one wire” unit which requires only the output wire to be attached. This is accomplished by a special internal regulator that does not require a voltage signal from the ignition switch to turn itself on or off but instead senses rotation of the rotor.

Converting from a generator to an alternator is quite simple. In some cases little or no wiring modification are required. Brackets to mount the new alternator are readily available now for the conversion from many suppliers. Lets take a look at differences of the two and how to make the conversion.

This typical generator is on a 1964 Ford. The car only has a heater and a radio so the power required was very low. The wires on the generator all go directly to the voltage regulator.

This close up of the terminals on the generator show, if you look closely, a G ( ground ) on the upper left. This wire goes to the ground terminal on the case of the regulator to tie the two together. The  F ( field ) on the upper right is the signal from the regulator that tells the generator when and how much current to produce. The remaining terminal on the end of the generator is the A ( armature ) output terminal.

The voltage regulator in the 64 Ford as well as many other model vehicles, was mounted next to the radiator for easy access. The regulator has the wires from the generator as well as one from the ignition switch (when a charging light is used in the dash) and one from the battery.

In most cases, as in this one, the case is labeled or stamped with what each terminal  does. BAT on the right is where the wire from the battery is attached. The  center FIELD terminal connects to the field terminal of the generator. The ARM terminal wire attaches to the armature terminal of the generator. 

This view of an older GM alternator shows an output terminal on the rear of the case with the main output wire and a voltage sensing jumper wire attached to the outer terminal of the regulator. This wire allows the regulator to know the voltage level of the system. The other wire attached to the inner terminal comes from the ignition switch. This wire turns the regulator on or off.

This universal one wire unit from Powermaster was installed on the 1964 Ford spoken about earlier. The engine looks different due to some clean up and painting. All the old wiring between the generator and regulator was eliminated except for the battery wire formerly attached to the BAT terminal of the regulator which was rerouted and  attached to the output post on rear of the “one wire” alternator. 

The rear view of the new alternator. Note the 2 wires on the output post. The original wire from the regulator, which was extended, was normally carrying 35 amps and now we have a 100 amp alternator. The second 10 gauge wire was added to carry the additional current.     Note:  The alternator can only put out what the wires are capable of carrying!