How Long Can You Run Onan Generator? (Explained)

how long can you run onan generator

You can run an Onan generator for up to 18-24 hours depending on fuel capacity, load capacity, generator type and size, fuel efficiency, fuel availability, maintenance and service, and environmental factors.

1). Fuel Capacity

This is the most critical consideration. Technically speaking, you can run your generator indefinitely. After all, it works by turning fuel into electricity. Theoretically, an Onan generator will keep running so long as it has a fuel source.

But a generator’s access to fuel is limited by the size of its tank. The larger the tank, the more fuel an Onan generator can hold and the longer it will run. When scrutinizing Onan generators in your local store, pay close attention to the number of gallons each unit can hold.

2). Load Capacity

What do you want the Onan generator to run? How many appliances will the unit operate simultaneously? This matters because the load influences fuel consumption.

The more devices the generator must accommodate, the faster it will deplete its fuel reserves and the shorter its runtime.

Eco Flow has published an equation that laypeople can use to calculate fuel consumption. It involves dividing the tank size by the generator’s kWh. The kWH is the generator’s electrical output.

They’ve given the example of a 5.4kWh generator with a 1.05-gallon tank. 1.05 gallons / 5.4kWh gives you a fuel consumption of 0.19 gallons per kWh. Knowing the fuel consumption per hour shows you how quickly the generator will deplete its fuel, which, in turn, allows you to estimate the runtime.

Don’t forget that a generator stops working once it runs out of fuel. This assumes that your generator’s output exceeds the total wattage of the appliances you want to run. If it doesn’t, you risk an overload. Use the following tips to increase the Onan generator’s runtime:

  • Limit the number of appliances running simultaneously. Stick to the most essential items.
  • Maintain the generator. Weld Power encourages consumers to service their generators semi-annually.
  • Use more efficient fuel sources.
  • Don’t overwhelm the generator. Use 50 to 80 percent of its capacity.

3). Generator Type And Size

Many people associate the generator size with the tank size. However, the variable has a bigger influence on the runtime than you think, especially when you expand the discussion to consider the generator type.

When you go generator shopping, your retailer will ask you to choose between portable and standby generators. The average portable generator promises an average runtime of six to twelve hours.

Depending on the model, you can extend that timeframe to 18 or 24 hours. However, portable generators have their limits. Running these units continuously for 24 hours is risky because of the excess heat they tend to generate.

The manual will tell you how long the unit can run before it requires maintenance. Stay within the recommended threshold to keep yourself and your family safe. Some generators will suffer permanent damage if you push them beyond their limits.

Standby generators are a different case. According to Petro Home Services, a standby generator can remain in operation for 500 hours or more. These devices can keep a small or medium-sized home afloat for weeks.

This makes sense once you realize that many factories remain operational during lengthy blackouts. The same is true for the many skyscrapers in your city. They rely on massive generators that run continuously for several weeks without stalling.

4). Fuel Efficiency

Given the choice, some laypeople will select diesel and gasoline for their generators because of their familiarity with these fuel options. But surprisingly, propane has an edge over the other two because of its superior shelf life.

If you routinely leave your generator in storage for long periods, you don’t have to worry about the unit’s propane reserves losing their potency. Gasoline and diesel don’t offer that benefit. However, don’t be so quick to elevate propane over gasoline and diesel.

On the one hand, propane burns more efficiently. On the other hand, Life-On-Route has found that propane delivers up to 15 percent less power. Keep that trade-off in mind before settling for a particular fuel option.

This is another area in which the manual’s recommendations should take precedence. If you can’t access a manual, consult a technician. They will analyze your situation before selecting the best fuel type that fits your needs.

5). Fuel Availability

Your fuel selection has a more significant impact on an Onan generator’s runtime than you think, and not simply because of its efficiency. For instance, as was noted earlier, you can keep a generator running indefinitely if it has fuel.

But there’s a limit to the amount of diesel a generator’s tank will accommodate. And once the diesel runs out, the unit will stop. This is why gasoline generators usually remain operational for 24 hours or less.

Diesel generators can run for hundreds of hours. But again, they will stop once their fuel reserves deplete. Admittedly, you can refuel a running gasoline generator. But the International Code Council warns against this practice.

Shut the Onan generator down and let it cool before adding gasoline to the tank. Otherwise, the heat from the engine will start a fire. Natural gas has an obvious advantage here. You can connect the generator directly to your home’s gas lines.

And if you have sizable propane tanks, they can keep your generator running for hundreds of hours. Refueling is less of an issue. It is a simple matter of switching gas lines. Does that mean a propane generator can run forever?

Not necessarily. Eventually, the oil in the engine will run out, and the generator will stop. As far as the availability is concerned, this report from the National Renewable Energy Laboratory has noticed that natural gas is more secure than diesel during a power outage.

You don’t have to worry about driving to a fuel station to get more natural gas. You’re more likely to run out of diesel than natural gas. On the other hand, you can lose gas pressure. Again, it’s a trade-off.

Each option has strengths and weaknesses. For instance, despite its reliability, governments will shut natural gas lines down during natural disasters to lower the risk of fires. The infrastructure in your location will determine the availability.

6). Maintenance And Service

Propane generators are more reliable in this category. Gasoline generators cannot run continuously for dozens of hours. They need a moment to cool down. But they are not unique in that regard.

Propane generators can also overheat if you run them nonstop for more than 24 hours. But you can mitigate that issue by aiming a fan at the engine. The oil is another concern. Depleting the oil in a propane generator can take 150 hours or more.

But eventually, it will run out, forcing you to add more. You can limit the instances of overheating by reducing the number and wattage of the appliances you connect to the generator at any given moment.

Pay attention to the environment. Keep the Onan generator away from extreme conditions such as rain, snow, and direct sunlight. If you typically use your generator in the wilderness (Camping), buy a canopy that protects the unit from moisture without restricting the engine’s airflow.

7). Environmental Factors

Some consumers think that environmental factors only matter where their fuel selection is concerned. After all, they can influence your access to natural gas and diesel. However, you should keep the threat generators pose to your health in mind.

Consumer Reports has noted that carbon monoxide can kill in as little as five minutes. The longer your generator runs, the higher the risk of carbon monoxide poisoning, especially when you position the unit in enclosed spaces.

Most homeowners are too smart to keep a running Onan generator inside. But sometimes they don’t have a choice. For instance, they will position the generator in a garage on a rainy night. But even if you leave the garage door open, the carbon monoxide can still drift into your home’s living quarters. For that reason, you should install CO detectors from a reputable brand.

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