How does the Reg work in an alternator?
The regulator (Reg) compares the voltage on the D+ terminal with an internal reference and then controls the output voltage (by regulating the current in the rotor which acts as an electromagnet) to maintain the output voltage the same as the internal reference voltage.
What should the voltage be on an alternator?
Alternator Testing: What Is The Correct Voltage? For some alternators, it’s normal to see as low as 13 volts. For some, a constant 13.6 volts is an indication of a problem.
What causes an alternator to over charge a battery?
Measure voltage across the battery with your DMM. You should get 0.5 to 2 volts higher than base voltage. If you are getting more than 2 volts above base voltage, most likely your alternator is over-charging the battery or the battery is faulty. Other potential problems are a faulty voltage regulator or a problem in the charging system wiring.
What makes an alternator and voltage regulator stop working?
Wires and connectors are the most likely culprits when things stop working. Just as with starter problems, track down each wire, switch and connector to see where resistance is high—above 0.2 ohms across any switch or connector—and/or where voltage drop is excessive—more than 0.5 volts.
Alternator Testing: What Is The Correct Voltage? For some alternators, it’s normal to see as low as 13 volts. For some, a constant 13.6 volts is an indication of a problem.
What should the voltage of a voltage regulator be?
Voltage Regulator Test Charging voltage can vary between 13.5 and 14.8 volts, depending on ambient temperature. In a nice, 70 F (21 C) day, you can expect a voltage regulator charging your car’s battery at about 14.2 volts. And the higher the temperature, the lower the charging voltage.
Can you bypass the voltage regulator on an alternator?
On many alternators (except those with computer voltage regulation), you can bypass the voltage regulator to test whether your voltage regulator or some other component (alternator or charging circuit) is at fault.
When to use battery light to test alternator?
The other critical tool to effectively diagnose an alternator is a scan tool. On older vehicles, the battery light would turn on the alternator light when the alternator output or battery voltage dropped below a preset value. The battery light on modern vehicles, however, is controlled by data and trouble codes.