This Portable Inverter Generator can run for a long time on a single tank of gas—up to 11 1/2 hours—Great for overnight.
How Long Can You Run a Portable Generator Continuously
The myths regarding how long a portable generator can run are a little amusing in that they range from minutes to hours and often include a caveat to shut down for a few hours or even a whole day to cool down and “rest.” One commenter claimed that if you didn’t shut it down every twelve hours and let it rest overnight, it would burn up and void the warranty.
Trying to correct all the misinformed advice would be like playing whack-a-mole. Instead, take look at the issue from a practical point of view and the reason people ask this question.
And while we’re being practical, let us point out that looking for good information on social media is an exercise in sorting through 100 pieces of bad advice to find the one gem that covered all the bases and got them right.
Hey! Safety First!
No kidding. Portable Generators are machines that run on internal combustion engines. They are powerful, carry hazardous voltages, and emit toxic fumes. They have the potential to kill, burn, main, or otherwise seriously injure you, your family, and others near by.
Portable Generator Safety Rules that Keep You Alive
That link covers most rules. Here are Three Portable Generator Safety Rules you must follow.
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- Never run a portable generator next to your home or inside your home. Keep the generator at least 10-20 feet away, preferably downwind where the exhaust won’t blow against your house or your neighbor’s house. No portable generator, even those with a CO sensor, should ever run indoors.
- Install a Carbon Monoxide Detector on every level of your home, including one near your sleeping areas.
- Never Backfeed Your Home with a Generator. Backfeeding your home means connecting the generator to an appliance outlet. It requires a cord with two plugs, instead of an outlet and a plug. Most retailers won’t sell them because they are dangerous and technically illegal.
How Long Can a Portable Generator Run Continuously
Short Answer: For as long as it has fuel and oil.
The average home user will choose between three fuels. Gasoline, Propane (LP), and Natural Gas (NG).
Gasoline generators were once the standard for home use, but that is changing. Generators that run on two or three fuels are becoming more common and the price for a dual fuel or tri-fuel generator has gradually come down. It’s better than doing a conversion yourself because running on propane or natural gas won’t void your warranty.
Portable Generators for Home Backup
Portable generator engines tend to use oil. They don’t have an oil filter. Air-cooled engines run hot and burn oil. When the oil runs out, the engine stops, often with catastrophic damage. Better generators include a low oil sensor or pressure switch and shut the engine down if the level or pressure falls too low. In either case, regardless of the source of fuel, eventually the generator will shut down.
Pro Tip: Some generators check the oil level. Keep it on a flat, level surface.
Most manufacturers recommend or require daily oil checks, or even more frequently.
If you’re running on gasoline, then you must shut down periodically to refuel. Follow the shutdown procedure and let the engine cool for 3-5 minutes. The oil will return to the crankcase and the dipstick reading will be more accurate. Add just enough oil to bring it up to the full line.
Now that your engine is cool, top the tank off with gasoline.
How Long Can a Generator Run Non Stop
Most manufacturers list the generator run time in the specifications, often at 50% load or 100% load. If you have a 5000 Watt Generator, 50% load is 2500 Watts.
Running at 100% of the generator’s rated load will shorten the generator’s life. It adds wear and tear to the engine and all the moving parts, including the alternator. Purchase a generator that provides a 20-25% margin. Do you need 5000 Watts? Find one that offers 6500-7000 Watts. Plus, if you ever need a little extra, you’ve got it covered.
When the generator is running with a load connected, try not to let it run out of fuel. Some dual fuel and tri-fuel models let you switch fuel types without shutting down. These are excellent for fuel economy and stretching the time between running to the gas station or propane depot. With a tri-fuel, you can switch to natural gas at night when the load is lower, and back to gasoline during the day when power needs are high.
A tri-fuel generator running on natural gas has a virtually endless supply of fuel. A dual fuel connected to a home’s 250-Gallon or 500-gallon propane tank has weeks of fuel. So how long should you run a portable generator on natural gas or propane?
Take a look at the generator maintenance section of the owner’s manual. It should tell you how often you MUST check the oil. It could be eight hours, twelve hours, or every day.
That’s how long should you run a portable generator. No longer than the manufacturer specified oil check period.
How Long Can You Run a Portable Generator
As long as you check the oil and top it off on time, as long as you need to.
The power is out and your portable generator is keeping the air conditioner, the refrigerator, freezer, and sump pump running on a hot, humid day.
Why would you shut down for hours? No need to do that. Keep the generator oil level topped off (don’t overfill) and refuel as necessary. Remember to let the generator cool before adding gasoline. Waiting a few minutes for the oil to settle before checking it after shutting the generator down is a good idea. Letting it cool before adding gasoline prevents flash fires in the event of a spill.
Don’t forget to change the oil on time. If the manual says every 50 hours, then every other day about the same time, follow the procedure to shut the generator down, let it cool for a few minutes, and then change the oil.
Pro Tip: If it’s near the oil change interval when you’re ready to put it away, change the oil first. That way, it’s ready to go the next time you need it.
Pro Tip: If you use your generator during power outages, keep at least enough oil on hand for 2-3 oil changes. Stock extra spark plugs and air filters. And if you happen to own a generator with an oil filter, stock a few of those, too.
How Long Will a Generator Run: Bottom Line
A long time.
Seriously. If you take care of your generator, it run for years, even if you run often for hours or days at a time.
“We run a generator on our job sites all week from morning to night, usually fifty to sixty hours a week. Every Monday morning, the new guy changes the oil and spark plug, and the air filter every other week. Our generator is 3 years old and had about 8000 hours on it, and I don’t plan to buy another one for two more years.”
Portable generators are work horses. They live in dusty environments. Work in hot and cold weather. End up stored for months in a garage until the power goes out in the middle of a storm. Then we expect them to start right up and not give us any trouble.
If we take care of them, do the maintenance on time, and don’t run them at 100% load 24/7, they will last for years.
About MJ Logan
MJ Logan began his writing career in third grade creating small booklets with a construction paper cover and two or three sheets of white typing paper, carefully folded in half and glued to the construction paper. His career led from electrical engineering and electronic test to network management, independent software development, and finally back to writing.
