How Long Can You Run a Generator Continuously?

Generators are great tools and have many uses – they are useful for everything from lighting up your camping trip to powering an outdoor party to keeping your home running during an emergency. Most of the time, you will need to use it for a short time, but extended power outages (especially in extreme weather) may require you to push a generator to its limits.

Which begs the question, how long can you run a generator continuously before you run into trouble?

Good question! A number of factors come into play, most import are the size of generator, the brand of generator, and finally fuel source.  Lets explore the most common situations below.

Portable Generator with Gasoline

If you’re running a portable generator on gasoline, unfortunately you will need to stop it from time to time instead of running it continuously.

With gas generators, never add fuel while the engine is running. It sounds easy to add gas, but doing so can be very dangerous and cause a massive fire.

When your generator is running it can get very hot, there is a risk that small spills or even fumes could start a small fire that quickly spreads to either the fuel tank in the generator or the tank you are using to refuel.  Dangerous! 

My best advice: turn off your generator for 5 to 10 minutes before adding more fuel.

With gasoline generators, you cannot really run it continuously beyond the standard runtime. For most gas generators that could be around 6 to 12 hours depending on the size, brand, and how much power you are drawing. Note that there are some options that run longer than others. 

The Westinghouse WGen3600v can run for 18 hours per tank – which is on the longer end of those we recommend.

Portable Generator with Propane

If you have a generator that runs on propane, you are in control of the fuel tank. That offers some additional options for keeping your generator continuously fueled.

The simplest way to extend your runtime with a propane generator is to hook up two propane tanks to a single gas line via a stopcock valve – or changeover regulator. That way, you can turn on the flow from one propane tank and leave the other closed. When it comes time to switch propane tanks, you simply twist the stopcock valve.

In this scenario, you can actually replace the depleted propane tank with a fresh tank so that you never run out of fuel.

So, assuming that you have an endless supply of propane, how long can you run your generator for?

Most portable generators require maintenance every 100 hours, but this isn’t a hard-and-fast rule. Instead, what will truly limit you is the amount of oil in your generator’s engine. This typically runs low after 150-200 hours of use, and most modern generators will automatically shut off when the oil runs low in order to protect the engine.

Keep in mind that heat build-up is also an important consideration when running your generator far beyond its runtime. Generators may build up only a marginal amount of excess heat over a 12-24-hour period, but once you go beyond a day of continuous use you risk building up engine heat that could permanently damage your generator.

If you’re running your generator in warm weather, consider packing it with ice and using a fan to try to cool the engine down as much as possible. Also keep in mind that running the generator at higher wattages will generate more heat.

So, if you manage your generator properly, you could potentially run it continuously for as long as 150-200 hours on propane.

Standby Generators

Lucky for us continuous power for longer term is possible, however a portable generator is not your best option. To run power continuously the best option is a standby generator.

These were designed for extended use.  Standby generators have efficient engines that are designed to run for longer time frames. They are also run on natural gas lines or connect to massive 500- or 1,000-gallon propane storage containers.

Do note that all standby generators do have a recommended limit. This typically averages around 2-3 weeks of non-stop power generation.

It is possible to run your standby generator for more than the recommended use. However doing so could cause permanent damage to your generator and your houses electrical wiring and appliances.

How Long Can You Run Your Generator?

To sum up, a portable gasoline generator can run continuously on a tank of gas but not longer without stopping. Typically 12-18 hours.

Using a large propane tank, you will find that your limiting factor is probably mechanical in nature (typically engine oil). For most propane generators that means around 5-8 days.

A large standby generator hooked up to a gas line can get you around 500 hours – or approximately 20-21 days.

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