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How long should I run my generator for monthly?

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Whether it’s for personal use or business use, if you own a generator you need to be aware of what maintenance is required to keep it running at peak performance and ensure it’s able to provide power when you need it.

Generators need to be reliable and in good working order, especially if they are to be relied upon for sudden and unexpected use. Several factors come into play when it comes to looking after your generator, throughout this article we’ll be looking at the practice of exercising your generator and how long you should run it.

Exercising your generator‘ is a term used for running the generator when it’s not needed to test it. It means starting up your generator once a week or once a month, to keep the generator well maintained, test it is working properly, and generating the power you need.

How often you need to do this depends on a few factors, such as the type of generator you own, the amount the generator is used, and the environment it’s kept in.

What you’re hoping to avoid is your generator failing to start when you need it the most and additional costs of a generator that needs further work or new parts as it’s not been looked after properly.

As a general rule, it is recommended most generators are exercised and tested between once a week to once a month to ensure it’s in good working order.

By getting the generator running for a few minutes of ‘exercise’, you’re testing all of its components, keeping the engine well lubricated, and can double-check the generator starts when it’s most needed, for example, if there’s a sudden power outage.

Exercising a Portable generator, Standby generator, or Whole house generator

If you have a house generator or are a business using standby generators for backup electricity, a weekly test is better to ensure it’s ready to generate electricity in the event of a sudden loss of power.

Portable generators that are used less often or for leisure activities, for example, can be tested monthly, the same applies to a generator that’s in regular use.

When you exercise your generator, run the generator without a power load for around 20-30 minutes. This is enough time for the generator to heat up and charge the battery if it has one.

Most generators should then be run with a load quarterly, every 3 months, for 15-20 minutes to make sure it can handle the full load when it’s required.

This will allow you to test whether the generator is producing enough power and energy to operate equipment and provide the right amount of electricity when needed.

Does a generator need to be run often?

Like with any engine you risk parts seizing and the unit failing to produce power if you don’t let the generator run occasionally.

Generator maintenance will help you to avoid the extra cost of repairs and help the generator run longer.

While you are exercising your generator, you’ll be able to perform a general maintenance check, such as doing an oil change, and charging the generator battery if it has one.

The same rules apply whether it’s a whole house generator, a portable generator, or a standby generator. They need to be exercised, especially if they are sitting unused for some time.

As we mentioned above, generators need to be run between once a week to once a month without a load, and monthly to quarterly with a load.

Some generators have an automated timer which allows you to set the time to exercise the generator.

Some companies run a test monthly, but for generators regularly required to produce power and energy, it’s worth setting this to test weekly.

Finally, the fuel source is important, especially if you’re using a timer. Generators won’t run on empty tanks, so make sure there is enough fuel in the tank to let it exercise. Electric start generators will need enough charge in the battery to start. So if you’re not manually testing, keep an eye it has everything it needs to run.

What should I do if I don’t use my generator often?

If your generator isn’t used often or it’s in storage, it’s still good maintenance to run your generator once a month or at least once a quarter.

During the test, it’s recommended you start with no load and gradually add appliances to build up to half load.

Generators that have been in storage or not used in a while should be run for at least 20 minutes before you put a significant amount of load on the engine.

Storing your generator? Empty the fuel tank

Generators put into storage should be made ready before doing so. Firstly, it’s worth checking your oil.

If you need an oil change you’ll need to let the new oil circulate in the engine before you shut it off. This will help keep the engine well lubricated during its rest, so next time you run your generator the engine runs smoothly.

If you’re doing an oil change, run the generator for a few minutes to allow the oil in the unit to heat, this makes the oil more fluid and it’s easier to empty the oil.

Lastly, if you’ve had the generator running, shut down the generator and let the engine cool, then drain the fuel tank of all old fuel.

Leaving untreated fuel in generators can cause a build-up of stale fuel and give you problems next time you try to power up your generator, so always empty the fuel tank before storing.

Is a monthly test required?

With most generators, a monthly test is required as a minimum. If your generator comes with a timer, set it to test at least monthly, and if you are manually testing it make sure you schedule a time to do so.

Your generator’s exercise cycle depends on a few factors, such as how much you use it. If it’s in regular use you may not need to exercise it so often. However, if the generator is in regular use you’ll need to make sure you are looking after it by keeping it topped up on fuel and checking the oil regularly.

If your generator isn’t used very often then other factors such as the environment the generator is sat in will come into play. If your generator is in a dusty or damp environment you’ll need to exercise it more often to clear it of contamination.

When your generator is not going to be used for some time or is going into storage, remember you’ll need to drain the fuel tank, unless you add a fuel stabiliser to the tank.


Exercising your generator is an essential process to test the generator and check it is working efficiently.

Depending on the generator type, how ofter it’s used, and the environment the generator is kept in, will depend if you need to exercise the generator monthly or weekly.

The cost of exercising a generator is minimal in comparison to what you may have to pay if you fail to do this. Yes the test requires fuel in the tank, but it keeps the battery charged, the components well lubricated, and reassurance your generator will start when you need it most.

Whether you’ve got a portable generator or standby generator, it runs on diesel or petrol, the team at Solent Power is happy to help answer your questions. Contact us today.

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Paul Phelps Solar Power Owner
Paul Phelps
Paul is the MD of Solent Power and specialises in emergency power solutions, helping to protect your facilities from power loss. Get in touch with us today to discuss the different power brands that we can offer and how they can suit your needs.
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