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How Long Can I Leave a Generator On For?

When the power goes out or you’re operating a generator at a campsite or other mobile location, it’s important to know your generator’s limitations. Extended use of generators is less than ideal – but, then again, generators are most often needed in less than ideal conditions. How long will a generator run continuously? How long will a generator produce power? Those questions have a single answer: it depends. We’ll provide some tips and some general generator information to help you determine how long your generator will run.

Of course, we have to say, your generator’s owner’s manual or other documentation will provide standard runtime and other information specific to your generator. Extending generator use beyond manufacturers’ recommendations can cause permanent damage and possibly void any warranties or guarantees. But here are a few notes on how long generators could run.

Portable Gas-Powered Generators

The average, standard runtime of a gas-powered generator is somewhere between 10 and 13 hours. The real runtime of gas-powered generators is dependent on the size of the gas tank – it will run until the gas is gone. It’s important to note that you should never add gasoline to a generator while it is running. The engines can get so hot that the smallest spill – or even fumes – could ignite a fire and make your power outage a lot worse!

With gas-powered generators, you’ll have to hit the power switch between fill-ups. You could, however, theoretically stop the generator to add gas and start the generator again. Gas-powered generators are designed for shorter-term use; you should use them for short periods of time to keep your refrigerators and freezers cold and shut them off while you’re away from your home or even while you’re sleeping.

The longest runtime for gas-powered generators is about 18 hours, although that will depend on your power usage and the type, brand, and size of your portable generator.

Portable Propane Generators

Propane generators offer the advantage of fuel tank control. That still might mean that you have to turn the generator off and replace a spent propane tank. But, with a stopcock valve or changeover regulator, you can attach two fuel tanks to the generator and turn the valve to the full tank when one is spent. Managing your changeovers and tank replacements can significantly extend the potential runtime of your propane generator. 

But even an endless supply of propane won’t keep your generator from stopping eventually. Generally speaking, generators should be serviced every 100 hours or so. What will actually stop your generator from running is a low oil supply inside the engine. Most modern propane generators automatically shut off when the oil is low to prevent engine damage or malfunction. That means your propane generator will be limited to a maximum (definitely not manufacturer-recommended) 150 to 200 hours of runtime.

Another thing that could stop your propane generator is an engine overheat. Especially if you’re running your generator in hot weather (not to mention the heat generated by the engine itself), consider packing your generator’s engine with ice and/or running a fan to keep it cool. Excessive engine heat from extended use of a generator can ruin the engine!

Standby Generators: The Big Daddies of Power

If you need a generator that can run for long periods of time, you really need to consider a standby generator. These generators are equipped with fuel lines and connected to massive propane or other fuel tanks. Designed with efficient engines for extended use, standby generators can get you through even major disasters and long periods without reliable power. Your standby generator’s runtime will be determined on the type, brand, size, power usage, and the size of your fuel tank.

Even monster standby generators have recommended use limitations. For most standby generators, that’s about 500 hours – right around three weeks. Standby generators can be run beyond their recommended runtime, but doing so could damage not only your generator but also your house’s electrical system.

Shop Generators with the Pros

At Northside Power, we know generators! We don’t just try to make a quick sale – our team of pros will listen to what you and your family need out of a generator and help you pick the perfect one. Contact us or come by for a visit crank up your home, camping, hunting, or other power supply needs!