How Long Can You Run a Generator

Owning a generator is an excellent investment at home. When you need to power your home during an emergency, when in a camping site, or when you need to run your power tools, a reliable generator is essential. Primarily, this equipment is used for short-term power needs. However, during emergencies, you may have to run it for long hours because of an extended power outage. It begs the question, how long can you run a generator? The duration depends on several factors, including the type of the generator, size, and fuel source. Read on to learn more about how long you can run your generator.

Types of Generator

There are three main categories of generators, namely;

  • Portable generator
  • Inverter generator
  • Standby generator

Portable Generators

These are mobile generators that run on gasoline, propane, or diesel to generate electrical power temporarily. Portable generators will supply your power needs wherever you are. Their runtime depends on the engine size, type of fuel, fuel tank capacity, and load.

Inverter Generators

These generators are connected to an alternator that converts the power generated into a stable AC output. In normal circumstances, inverter generators are compact and lightweight to enhance their portability. You can easily fit one into you’re RV, car, or boat.

Inverter generators can either run on gasoline or propane. Don’t be surprised to find dual fuel inverter generators in the market running on either fuel source. Such inverter generators are versatile because they allow you to meet your power needs depending on the available fuel source.

Standby Generators

how long can you run a generatorIt’s a backup power solution that turns on automatically when the primary grid goes off. It has an automatic transfer switch that detects the power loss and alerts the generator to run and supply power to a building’s circuit. The sensors in this generator command the unit to stop when the main power returns.

These are bulky generators, and they are not portable. You can only use them in a residential or commercial building to serve as an emergency power backup system. In most cases, they are diesel-powered, and they are noisy units, but you can also find other models running on propane or gasoline.

More information on the types of generators

So, how long can you run a generator?

Running Portable Generator with Gasoline

how long can you run a generatorWhen running portable generators on gasoline, you will have to schedule how you will refuel them from time to time. And because you cannot refuel a portable generator when it is running, you will have to turn off the generator for about 10 minutes. One of the significant reasons generators should power off before refueling is that a running generator has hot surfaces. When these hot surfaces come into contact with spilling fuel, it can cause a fire.

Therefore, portable generators running on gasoline cannot run continuously beyond their estimated runtime. The estimated runtime for most portable generators is a maximum of about 12 hours. However, it depends on the generator’s size, the amount of power you’re drawing, and the brand of the generator. Certain brands of portable generators like Westinghouse WGen3600v have an extended runtime of about 18 hours per single tank.

If you need a portable generator that runs for long hours, it should have a big fuel tank and don’t run it on full load.

Running a Portable Generator on Propane

It is easier to extend the runtime of a generator that runs on propane. This is because you can hook up two propane gas tanks to a single line feeding the generator. You can make this possible by using a changeover regulator and stopcock valve. With dual sources of propane gas, you can allow one source to flow to the generator while the other is blocked. When it is time to change the tanks, you only have to switch by permitting the unutilized tank to flow to the generator by twisting the stopcock valve.

Replace the depleted propane tank with a new one, and you can keep changing the tanks without having to power off the generator. It will guarantee you a continuous power supply, but for how long will you run the generator?

Most portable generator brands require a maintenance service after running for 100 hours. However, the oil level in your generator may also determine whether the unit can run for that long or not. If your generator has a low oil level, it is likely to auto shut down to protect the engine and extend its life; this feature is available in modern portable generators. Most portable generators require an oil change after 150 to 200 hours of running.

Even though you can run the generator for up to 100 hours when interchanging your propane tank, you should be conscious of overheating scenarios. Portable generators can start overheating when they run for long hours, especially when the runtime goes beyond 24 hours. Overheating can, in return, damage your generator’s engine or lower its lifetime.

You can avoid overheating the engine by placing a pack of ice near the generator or having fun near the generator as it is running. Doing so will help you cool the engine as the unit is running. Even so, a generator can also overheat when you are drawing high wattage from it.

So, with good management, you can run your portable generator continuously on propane for around 150-200 hours. You should also watch out for the oil level of the generator.

Standby Generators

A standby generator allows you to power your house for continuous hours, longer than what a portable inverter generator can allow. Standby generators are for extended usage because of their efficient engines, making them use less fuel, guaranteeing an extended running time.

You can also connect a natural gas line to your standby generator or connect it to a massive 1000 –gallon propane storage container.

Standby generators have a recommended maximum runtime of about 2 to 3 weeks (approximately 500 hours) non-stop. You can extend the runtime, but doing so may compromise the wellness of the generator and may damage the wiring of your house.

It is important to note that generators should not be sued as a primary source of power regardless of how long the generator can run. It is ideal to use your generators in scenarios where you need temporary power solutions, don’t substitute it for your main grid.

Check Out this Video on How Long Can You Run a Generator

Reason Why You Should Not Use Your Generator as Main Power Source

  • Generators Have a Limited Lifespan

Regardless of your generator brand or type, it is not meant to last forever. The lifespan of a generator depends on how well you will maintain it, how long it has been in use, and the brand. Maintaining and replacing a generator after a couple of years can be expensive compared to installing and maintaining grid power.

  • You Cannot Use Generators Continuously Over Long Period

Regardless of the type of fuel you use on your generator, you are likely to stop it before refueling it. You have to power it off and give it ample time to cool before refueling. Secondly, generators require regular maintenance, just like your personal car. For instance, you have to check and top-up oil periodically, clean it and replace some accessories such as plugs. This means there are times when the generator has to be off for any maintenance to be effected.

  • Generators are More Expensive to Run Than Grid Power

It will cost you a lot more money to fuel your generator daily. With the rising fuel cost (diesel, gasoline, and propane), powering your generator every day is costly than paying for your monthly electricity bills. According to Mr. Electric, running a generator every day can cost you $52-$200 a day, depending on your fuel source. On the other hand, the average cost of daily grid power is $3.72. the difference is big.

Easy Tips for Buying a Generator that Lasts Long

how long can you run a generatorEven though standby generators can run for more extended periods than other types of generators, standby units can cost you between $2,000 and $20,000 on average. Such a cost requires one to have a big budget which is not usually the case with most homeowners. As a solution for that, here are easy tips for sourcing a long-lasting portable generator;

Consider a Diesel-Powered Generator

Diesel generators are the most fuel-efficient generators. Whether they are standby or portable generators, they have a long runtime than gasoline or propane-powered units, even when both are running on the same load.

An alternative to diesel-powered generators is a propane-powered unit. Propane as a source of fuel is more efficient than gasoline.

Consider a Generator That Has a Big Fuel Tank

One of the factors that determine the runtime of a generator is its fuel tank capacity. A generator with a small fuel tank will require periodic refueling, necessitating you to shut down the generator from time to time. A big size fuel tank means the generator will run for an extended period before you refuel it.

Check Out the Manufacturer’s Instructions

Reliable generator brands have a stipulated runtime on their product description. This means different generators will have varying runtime. Before settling for any model, check the description and settle for the one offering a long runtime. However, you should also consider the generator’s power output; while looking at the runtime, do not compromise your demands.

Get Multiple Propane Tanks

Even though running a generator on propane will not give a long extended runtime compared to running it on diesel, you can extend the runtime of a propane powered-generator. Invest in multiple propane tanks and hook two of them in a single generator and allow it to run on one tank to completion, and switch to another tank before the generator shuts down. However, this will also depend on the availability of propane gas in your state.


Once you have settled on your favorite portable generator based on the runtime it offers, your next role is to provide maintenance services. Poor maintenance can lead to the malfunctioning of a generator even when it is six months old. Regular maintenance, as per the manufacturer’s instructions, will extend the life of your generator.

What is the Lifespan of Generators?

There is a difference between the number of years you will be able to use the generator and the warranty period given by the manufacturer. Most manufacturers provide a warranty period that ranges from 2 to 3 years. During this period, the manufacturer expects the generator to serve you without any complications. And if they should arise, the manufacturer repairs or replaces the generator free of charge. The manufacturer believes that the unit will last within its warranty period without any technical problem as long as the generators are subject to normal usage.

In real-life situations, generators have a long runtime than the warranty period depending on your load. In most cases, generators can serve you for more than twenty years if you are using them for an average of 500 hours annually. However, for a generator to serve you this long, you have to ensure that you service it regularly and operate with adequate oil.

Generators that run daily for about 8 hours, 7 days a week, will have a shorter lifespan than a generator with an average of 500 hours annually.

Maintenance Tips of a Generator

For a generator to serve you efficiently, you have to follow a manufacturer’s maintenance schedule. Besides the manufacturer’s maintenance schedule, you can also conduct routine inspections, which involve checking the oil levels, the coolant, and whether the generator has some leakages. Thorough generator maintenance maintainance involves;

  • Checking battery power:

Most standby generators fail to work because of battery issues. Such generators have a sensor that requires battery power to detect when the main grid is disconnected. You will therefore have to ensure that the battery is strong and fully charged at all times to avoid any start-up hitches.

  • Conduct regular testing to check the generator’s status:

You don’t want to realize that your generator has a problem when there is an emergency. Conducting regular testing, especially when the generator has not been in use for a long time, can save you from a malfunctioning generator when you need it most.

  • Replace your generator’s filters after 500 running hours:

You should regularly replace your generator’s fuel and air filters, especially if you own a diesel-powered generator that runs frequently. Unclean fuel and air filters can lead to the malfunctioning of the generator.

Frequently Asked Questions

Is it wrong to run a generator for a long time?

This depends on the type of generator, amount of power you are drawing, and the size of the generator. Generators running on gasoline cannot run beyond their specified runtime by the manufacturer. Most portable generators running on gasoline have an average runtime from 6 to 12 hours. However, some can run for up to 18 hours non-stop.

Does a generator consume more fuel when you plug in more electronics?

Yes. A generator’s fuel consumption rate depends on how much power you are drawing from the generator. Plugging in more appliances means the generator is loaded, and it is required to supply more power which increases the engine’s speed. This explains why generators runtime is defined using the percentage of load the generator has.

How long can a propane-powered generator run continuously?

A propane-powered generator can run for as long as there is propane gas flowing into its engine. A 500-gallon tank of propane can power a generator for a week running 24 hours a day. However, to achieve this runtime, the generator should be well maintained.

Final Word

How long can you run a generator? It depends on several variables, including your type of generator, size, and fuel source. Standby generators last for long hours because they are made to run efficiently on fuel regardless of the load, especially when running on diesel. Propane-powered generators can also deliver long runtime compared to gasoline-powered units. Furthermore, you can extend the runtime of propane-powered generators by connecting two propane gas to power a generator but one at a time. However, you need to ensure the generator has adequate oil levels; otherwise, it will stop running when it is low.

Please do not use it as a substitute for your main electricity supply for the best results from your generator. Instead, only use it as a power backup plan. The primary role of this equipment is to meet your temporary power demands.

About Steve Stuart

Steve Stuart is an electrical engineer who developed interest on generators during his school years. After school, he became a generator enthusiast. This is after encountering power supply problems at the area of residence where he lived. Power would be on and off and so food would go bad and the room heater would go off especially during winter. After trying the different generator brands for several years, Steve now provides information on the available brands and products in the market today. Based on his experience, he gives the do’s and the don’ts when it comes to generator use.

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