System polarity, and Polarizing Generators:
Question:
Some advice and tips for system polarity, and polarizing generators
Answer:
Most automobile electrical systems that use DC generators can be set up for either positive or negative ground (alternators require different internal parts). I have yet to see an advantage to changing from the original design. The starters are series wound and will always turn the same direction. Ammeters and some other gauges are polarity sensitive, and reversing polarity can damage some of them. Radios and other electronics will not work and are often ruined by reversing the polarity. The ignition coil will operate if the polarity is reversed but the spark produced is not as strong.
As for why anyone would want to change polarity, I believe you answered the question with your statement about radios and electronics. People change polarity and go to 12 volts from six so they can use modern accessories such as CD players, AM/FM radios, afler-market air conditioning and other modern conveniences.
Polarizing generators:
Polarizing the generator is done with everything connected but the engine not running. Momentarily employ a jumper from the “BATTERY” to the “ARMATURE” terminals. The generator Field terminal is grounded through the regulator when at rest, and to the hot side of the armature internally —a brief shot of DC current is all it takes to create a residual magnetic charge in the pole shoes that will be of the correct polarity and enough to create the voltage on the armature to bring the regulator into operation when the minimum speed is reached. Zapping the field terminal on a DC generator that has no external connections does nothing—zapping the field terminal on a DC generator that is connected can damage the voltage regulator.
Actually there are two types of generator and voltage regulator combinations used with DC generators, known as A and B systems. In an A circuit system, the field is grounded through the regulator. The A circuit systems are common in earlier Ford and GM vehicles. However, earlier Chrysler vehicles had a B circuit system that was grounded internally through the generator.
To polarize an A circuit system, you connect the Field, Armature, and Battery leads to the regulator and then connect the battery. Then you momentarily connect a jumper wire between the Armature terminal and the Battery terminal at the regulator.
To polarize a B circuit system, you need to connect the Field and Armature leads to the regulator. Then, just before connecting the battery lead, momentarily touch it to the Armature lead terminal.
