On June 6, 2025, we launched a new podcast about fixing portable generators, which you can find here:
https://auroragenerators.com/blog/podcast/fixing-portable-generators-no-power/
What Causes Generators to Stop Producing Power/Voltage?
The most common cause of portable generators failing to produce electricity is the loss of residual magnetism.
Generators work by moving electrical conductors through a magnetic field. Your generator does not have magnets. The magnetic field is created by converting some of the generator output voltage to DC and feeding it to a coil to make an electromagnet.
When a small amount of magnetism remains from the last time the generator was running, it is called residual magnetism. This little bit of magnetism is enough to produce a small amount of electricity, which is needed to create an even stronger electromagnet. As the engine turns this magnet, moving its electric field through the stator windings, your generator produces even more power.
When the residual magnetism is lost, the generator will produce no power at start-up.
Detailed Explanation of Residual Magnetism
Residual magnetism is the small amount of magnetism left in the iron core of the generator’s rotor after the generator has been shut down. This residual magnetism is crucial because it serves as the initial magnetic field required to generate electricity when the generator is started again. Without residual magnetism, the generator’s excitation system cannot kickstart the production of electricity, leading to a failure in generating power.
Residual magnetism can diminish over time due to various factors:
- Prolonged inactivity: Generators that sit idle for long periods may lose their residual magnetism.
- Connected load during shutdown: Turning off a generator while a load is still connected can cause a loss of residual magnetism.
- Running without a load: Operating a generator without any load can also reduce residual magnetism.
Preventive Measures
To maintain residual magnetism and ensure your generator continues to produce power, follow these preventive measures:
- Regular use: Regularly running your generator helps maintain its residual magnetism.
- Load management: Always disconnect the load before shutting down the generator. This prevents the residual magnetism from draining.
- Avoid running out of fuel: Ensure your generator has sufficient fuel to avoid unexpected shutdowns with a connected load.
- Apply a load: When running your generator, ensure it is operating with an appropriate load. This helps to sustain a strong magnetic field within the generator.
How to Fix It
There are a few methods of restoring a generator’s residual magnetism:
12 Volt Generator Battery Method
- Locate the voltage regulator for your generator. Unplug the two wires that connect to the generator brushes. Normally, one is red, and the other is black or white.
- Connect the black or white wire to the generator ground battery terminal.
- Plug in a light, turn on the generator breaker or switch, and start the motor.
Connect the battery +12 volts (red cable) to the red wire on the terminals you removed for three seconds.
Safety Note: Ensure you unplug the brush wires from the automatic voltage regulator, or you risk damaging the regulator. Avoid contact with the voltage regulator or other wires, as dangerous voltages may be present that can cause electric shock.
Electric Drill Method
- Plug an electric drill into the generator receptacle. If the drill is reversible, move the direction switch to the forward position.
- Start the generator.
- While depressing the trigger on the drill, spin the drill chuck in the reverse direction. This will excite the field, and the generator will now produce electricity. If spinning the chuck in one direction does not work, try spinning the chuck in the other direction, as you may have the reverse switch positioned backward.
Safety Note: Avoid getting your hand or other materials caught in the chuck. As soon as the field is excited, the generator will produce power, and the drill will turn on.
This method works because the electric motor in the drill acts as a small generator when spun backward. The magnets in the drill’s motor induce a voltage into the motor winding, which is fed back through the trigger cord and into the generator receptacle. From there, it goes into the power winding of the stator. The voltage going through the power winding creates a magnetic field, which is intensified due to the iron core of the stator laminations. The rotor intersects this magnetic field as it is spun past the power winding, thus inducing a voltage in the rotor winding. Once the current flow is present in the rotor winding, the rotor has been flashed.
Additional Troubleshooting Tips
If the above methods do not restore generator output power, consider the following steps:
- Check the Automatic Voltage Regulator (AVR): If the AVR is faulty, the generator may not produce power. Replace the AVR if necessary.
- Inspect the Exciter Field: Ensure there are no loose connections or damaged components in the Exciter Field circuit.
- Examine the Stator and Rotor Windings: Look for signs of wear, damage, or burnt windings, and replace or repair as needed.
- Test the Generator’s Capacitors: Faulty capacitors can prevent the generator from producing power. Use a multimeter to test the capacitance and replace if necessary.
- Consult a Professional: If you cannot diagnose or fix the problem, consider consulting a professional technician specializing in generator repair.
By following these steps and preventive measures, you can maintain your generator’s functionality and ensure it provides reliable power when needed.
Conclusion
Understanding the importance of residual magnetism and taking steps to maintain it can help prevent generator failures. Regular maintenance, proper shutdown procedures, and timely troubleshooting are key to ensuring your generator remains a reliable power source.
For more detailed guidance and expert assistance, please get in touch with Aurora Generators. Our team is always ready to help you with your power needs.
Please review this updated content and let me know if you have any changes or additional details you would like to include.
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