Generator Care Generator Maintenance

How Many Hours Can You Run a Generator Continuously?

Whenever there is a power outage, starting a generator is the first thing that comes in most homeowners’ minds. If the situation extends more than few hours, you might begin to wonder how long you can run a generator continuously. The same dilemma will hit when camping or outdoors.

A gasoline generator can only run as long as the amount of fuel in its tank allows. If it’s a portable propane generator, you can run it safely for 12-24 hours as long as there’s no heat buildup. If it’s a heavy-duty standby generator, you have the freedom of running it for up to 500 hours when you’ve to carry out the necessary maintenance routine.

How long you can run your generator is affected by few factors I will discuss in this post. You must understand what goes on when the engine runs continuously without rest. Read along.

How Long Can You run a Generator Safely?

The best way to answer the question is to divide the topic based on the generator involved. Portable (gasoline or propane) generators and standby generators being the most common options available.

a) Portable Generator

A portable generator is the most popular and most-used generator. It’s widely versatile, allowing users to use it at home, on the road, or at a job site. At home, you can use it to run your home essentials, including the sump pump. Most portable generators are either gasoline-run or dual fuel, which can run on both gasoline and propane. So, how long can you run these types of portable generators?

Usually, a portable generator engine is built to handle not so much operation. It’s constructed primarily to provide power in emergencies and small job site power. Their operations are limited, considering they can build up heat when the engine runs continuously.

These unit engines are air-cooled, meaning with time, the engine will build up a considerable amount of heat capable of causing problems. What’s more, their small oil reservoir can hold much oil to last much longer. When you run the generator continuously, the oil will get dirty, losing its effectiveness, and it’ll need replacing.

Portable Gasoline Generator

If your generator uses gasoline only, you can only run it as far as its runtime can get you, after which you will need to shut the engine off and allow it to cool down before refueling it.

So, if you want to run your gasoline generator continuously, you only have one option; fill the gas tank with gasoline and run only the essentials to try.

If your generator has an eco-mode, you can turn it on allow the engine to run with variable speeds, thus reducing the fuel usage.

But once the fuel tank is empty, you must shut down the generator to refuel it safely, which will cut the continuousness you’re looking for.

It’s highly tempting to refuel while the engine is running, but it’s hugely dangerous as the hot engine could ignite the fuel and cause a fire hazard.

Therefore, you must avoid it entirely and shut down the engine; give it some time to cool down before refueling it.

So, how long does your generator run with the full tank full? A couple of hours or a day? Even though the generator runtime dictates how long you can run your generator, understand that you can only run it as the engine allows.

The generator engine might get too hot and cause early wear and tear problems if you run it too long. The maximum time you can run your portable gasoline generator is 12-15 hours depending on its size, type, and the amount of power drawn from it.

Open-frame generators can run for extended periods since their open design allows the engine to cool down faster when run in an open, well-ventilated, and cool area. The same can’t be said with inverter generators because of their whole body enclosure.

Check the generator’s runtime at quarter-, half-, and full-load to know how many hours you can run your generator before the next refueling.

Even though it’s not often that you will need a generator to run for so long, you must give it some time to cool down.

Portable Dual-Fuel Generator

A dual fuel generator is capable of running on gasoline or propane. That brings out a new possibility of running the unit past its average gasoline-rated runtime. The technology allows you to choose the most convenient fuel source between these two. The best part is, you get the freedom of extending the generator runtime, something you can cherish if you’re outdooring.

These generators have a fuel selector switch allowing you to switch from gasoline to propane safely. The fun part about this is, you cannot run on both without keeping the other line off. However, the generator engine has to stop when switching to the additional fuel source. That means, if you’re running the generator off gasoline, you’re limited to its runtime.

However, when running on propane, the control of the generator is on your hands. You can decide to go with the recommended LPG tank or use the biggest you can get, not recommended at all – I will tell you why.

You can even connect two propane tanks, and when one is depleted, you use a stopcock valve to switch from the almost empty tanks to the full tank and extended the runtime. Some models can even run on tri-fuel, allowing you to hook it up to your natural gas line with an unlimited supply of fuel.

Ass you can see, the control is in your hands. However, there are some factors that will still limit how long you can run a dual-fuel or tri-fuel generator with an unlimited supply of propane or natural gas, such as

  • Maintenance requirements
  • Engine heat buildup

A portable generator, be it gasoline or dual-fuel, is built to operate to a certain point and rested before starting the engine again. It cannot handle long-hour operation – if forced, the generator engine will begin to wear out faster than expected.

One thing that can cause this is oil getting dirty and requiring change. You’re supposed to run your generator for the first 20 hours of its operation life and change its engine oil. After that, you’re required to the oil after 50-60 hours of operation afterward.

That means, if you’re running the generator for the first time, you can only run it for 20 hours before shutting it down and changing its engine oil. If you already did the first oil change, the generator can run continuously for 50-60 hours until when you have to shut it off, allow it to cool down, and change the oil again.

During these extended runtimes, the generator engine builds up heat that can damage its internal parts or accelerate wear and tear. When running the generator on unlimited propane or natural gas supply, consider keeping an eye on it.

Make sure the heat buildup isn’t so high. You can use a fan to keep the engine cool as it operated – it looks ridiculous, but it can help.

b) Standby Generators

If you’re using a standby generator, then continuous operation might have never being a question for you. These units run on massive diesel tanks, huge propane tanks, or a continuous supply of natural gas flowing through a home.

And since their engines are heavy-duty, they can run well beyond 200 hours quite comfortably and not experience any problems. You can run it for few days without worrying about what would happen. However, like any other machine, it does have its limits.

So how long can you run a standby generator continuously? It all comes to the following maintenance routine after 500 hours, when you have to change the oil. You have the option of carrying on for a few hours, but that will be risking permanent damage to your generator engine.

Is it Safe to Run a Generator Continuously?

I get it; some situations call for the continuous power supply but is it essential. Can’t you stay without power for 30 minutes or so as you maintain your generator?

It’s never safe to extend a generator’s runtime to meet your needs, especially with a portable generator. These units can only handle too much stress in the engine. Extending their runtime could cause catastrophic failure and be forced to invest in another generator.

So, even though there’s a possibility of extending your dual- or tri-fuel generator’s runtime, consider using the recommended LPG tank to keep the generator well under the tested runtime.

If it’s unconditionally crucial that you keep the generator running during an outage, make sure you change the engine oil after its first 20 hours of operation and after 50-60 hours of operation afterwards. If it’s a standby generator, change the oil after the first 500 hours.

Related Questions

Can you run a generator overnight?

Yes, so long as the fuel tank has enough fuel allowing it to run overnight. However, you need to make sure it’s in a secure spot, especially camping.

Can a generator run 24 hours a day?

It depends on whether the generator runtime allows it and handling the heat buildup during this operation period. If your generator runtime is over 24 hours and it’s an open-frame model, you can run it 24 hours a day in a cold and dry spot. However, you’ll have to carry out the maintenance routine like checking the oil level after 24 hours.

Is it legal to run a generator all the time?

Running your generator isn’t an issue in most cases, especially if you’re using it for backup purposes. But if you live in a densely populated area and you try to run the generator to supplement the utility power, you might get yourself into trouble. There might be local ordinances and neighborhood rules that you might be breaking.

About the author

Sharif Gen

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