Does a Generator Slowly Lose its Residual Magnetism With Time?

Ian Mutuli
Updated on
Ian Mutuli

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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Power outages are unavoidable. Therefore, all homes need at least one power backup plan. Generators are the best option as they do the best job when it comes to lighting homes. However, generators sometimes run but don't produce electricity. So, does a generator slowly lose its residual magnetism with time? The clear and direct answer is yes; a generator does lose its residual magnetism with time. How does this happen? Let's find out about that below.

What is Residual Magnetism?

Generators work by passing electrical conductors through a magnetic field that they create themselves. Magnets, on the other hand, are not found in generators. Instead, the magnetic field is formed by converting a portion of the generator output voltage to DC and feeding it into a coil to create an electromagnet.

Generators use a phenomenon known as residual magnetism to start up. This is a small amount of magnetism that was leftover from the magnetic field created the last time the generator ran. This modest amount of residual magnetism is sufficient to generate a small amount of power.

An electromagnet is made with this minimal amount. Your generator will produce more power when the engine turns this electromagnet, moving its electric field through the stator windings. Your generator will produce no electricity at starting if residual magnetism is lost.

Why Do Generators Lose Their Residual Magnetism?

Generators may lose their magnetism in different ways. The generator will not produce any electricity when the residual magnetism is removed. This residual magnetism can be lost naturally when the generator is not in use or when the load on the generator is connected when it is turned off.

Your generator can also lose its residual magnetism if it runs without any load for too long. Again, this leads to the loss of magnetism over a while.

It can also result from long-distance transportation vibration. Again, this is true if it's a new generator.

How Can You Restore Residual Magnetism

If there is no residual magnetism, your generator will not produce power, even if you keep it running. Therefore, you will need to restore the magnetism needed to begin voltage buildup to keep using your generator as soon as possible. You can restore it by following the steps given below;

a). Using a 12-Volt Generator Battery Method

Firstly, you will need a 12-volt battery to get started. You can even use a car battery if you have a small generator. Next, locate your generator's automatic voltage regulator. Finally, disconnect the two wires that run to the generator brushes.

One is usually red, and another is black or white. To the generator ground battery terminal, connect the black or white wire. Next, connect a light, activate the generator's 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. Replace the plug after removing the wires. The generator should now be producing electricity once more.

b). Using the Electric Drill Method

Connect an electric drill to the generator outlet. Move the direction switch to the forward position if the drill is reversible. Fire up the generator. Spin the drill chuck in the other way while depressing the drill trigger.

This will excite the field, resulting in the generator producing electricity. Whether spinning the chuck in one direction fails, try spinning it in the opposite direction to see if the reverse switch is set backward.


Generators lose their residual magnetism with time. This is usually because of running it for too long without a load, shutting off a generator while it is still loaded or even when the generator is not used for a long time. However, the good news is that you can reverse this situation easily.

Image: My generator

Ian Mutuli

About the author

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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