How Long Can You Run Your Diesel Generator?

Knowing how long your diesel generator can run is important when it comes to planning for power disruptions, maintenance and ensuring the generator is operating to its full potential.

What Affects Generator Run Time?

Generator run time depends on several factors, including the type of fuel used, the load on the engine, and other environmental factors like temperature.

Generator Size

The size of the diesel generator plays a key role in its operating time. Typically, larger generators are designed to run longer than smaller generators without needing fuel replenishment, though smaller generators can still provide several hours of continuous power under normal load conditions.

Generator Load

If your application requires more power from the generator than it can produce for extended periods of time, then it won’t be able to run as long as it would if it was under less stress and producing less power. When choosing a diesel generator for your application make sure that its output rating is sufficient for all of your needs so that it doesn’t need to work too hard or too long in order to meet those needs.

As part of our generator commissioning service, our service engineers load test the generator to ensure that it will support your load.

Prime Power vs Standby Power

A prime power generator is used to provide the primary power source for the equipment it is powering. Generators that are used for prime power are designed to run for long periods of time whereas a standby power generator is used when there is a disruption to the mains power for short periods of time.

Diesel Fuel

The quality of your diesel fuel impacts the safety and reliability of your generator. Fuel can become contaminated over time and start to degrade, and can lead to engine failure.

If you are planning to use your generator for long periods of time or want to store your diesel fuel in the optimal conditions, Shanahan Power can also supply fuel tanks.


Regular maintenance is essential in ensuring that you get the most out of your investment and maximises the lifespan of your generator. Neglecting your generator maintenance can lead to your generator failing or needing more serious repairs or replacements.

Here are our top tips for keeping the health of your generator in check in between maintenance visits:

  • Undertake a visual inspection – Problems with your generator can be uncovered with a thorough visual inspection – check parts like hoses and belts for any leaks and signs of wear. Also check your fuel, oil, and coolant levels.
  • Use high quality fluids – Your generator will run best with high quality coolant, oil, and fuel. Avoid contaminants and build-up that interfere with a generator’s performance by choosing high-quality fluids and testing the fuel regularly to ensure it is not degrading.
  • Run your generator regularly – Low usage of your generator can cause wet stacking’ or build up in the engine exhaust and air in your fuel system, leading to damage to the internal parts of your generator. It’s important to run your generator regularly for a short period of time to avoid any issues.
  • Only use Original Equipment Management (OEM) parts – OEM parts, including air filters, fuel filters and oil filters that are endorsed by the generator manufacturer can extend the life expectancy of your diesel generator and provide a predictable expense for your business.

At Shanahan Power, our Asset Care Management service guarantees that you won’t get left in the dark with regular maintenance by our service engineers, and access to our 24/7/365 Breakdown Assist facility. Contact us to find out more!