How Long Do Generators Last With Correct Maintenance?

Ian Mutuli
Updated on
Ian Mutuli

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
Get Smarter On Architecture and Design

Get the 3-minute weekly newsletter keeping 5K+ designers in the loop.

Enter your Email to Sign up


A power outage wields real power that can either break or make your day - you'd wonder how the early man survived. So you went out and got yourself the best generator to act as a backup generator deal with all those power outages or simply needed a portable generator you could use to run machines while outdoors. The ultimate question this far is, "How long do generators last with proper maintenance?"

Well, in all honesty, there's no simple or straightforward answer to this question for most generators. A few major factors will influence exactly how long your generator can run continuously after being fired up. Typically, portable generators will not last as long as the generators that are stationary. Its durability will also depend on the quality of its engine.

You can expect most portable generators to last between 1000-2000 hours. This means if you run your portable generator for an average of 100 hrs per year, a well-maintained generator will last you between 10-20 years. However, the life expectancy of portable generators can be dramatically reduced by several factors, such as excessive exposure to moisture or dust, so it's quite important to properly store and maintain it.

Portable Vs. The Standby Generators

Portable and standby generators can last and run on standby at different rates since these two are two completely different beasts. Additionally, standby generators should cover a standard of performance requirements by the NFPA state.

Standby generators are largely backup generators with permanent features that are attached to the house and are always ready to fire up and light up the entire house the instant power is lost. On the other hand, portable generators will need you to manually pull them out and fire them up during the power outage or whenever needed.

Here are the main differences between standby generators and portable generators:

A) Size And Use

Standby generators

Generally, standby units are larger than their portable counterparts. This means that they also have varying wattages and fuel feeding methods. Since backup generators are mainly designed to run non-stop to power your entire home for days, they're mainly built to be durable and run for long.

Portable generators

Portable generators, on the other hand, are built for just a few hours of running, so they might not be a realistic solution when it comes to a long-term electricity solution

B) Capacity

Standby generator

Typically, they carry 7,000-150,000 Watts which can power your entire home, depending on the size.

Portable generator

Typically, these generators have the capacity of a few hundred Watts to 7,000 Watts. In some instances, some are as large as 15 kW. These generators are built to only power 'just a few appliances only.

C) Space And Installation Requirements

Standby unit

These units are generally installed outside the house, mostly by a certified dealer under the approved state guidelines. You will need a level surface to install it on a pre-fabricated concrete pad. It's often mounted on a skid base as well. It's normally quite larger in size, roughly from 3-10 feet in length, and approximately 5 feet in height. It also comes in a weather-protected enclosure that's often sound attenuated.

Portable unit

These units don't need any installation necessary but will have to be stored indoors and only placed outdoors when needed for use in the operation of any appliances. Generally, it usually comes in the size of a large dog crate carrier.

D) Maintenance

Standby unit generator

These units need to be properly maintained, with periodic monthly and yearly maintenance by a certified technician.

Portable unit generator

Portable units need minimal maintenance that can be performed by the owner.

E) Durability

Standby unit

These units have air-cooling engines that can last up to 1000 - 1500 hours, while the liquid-cooled engines can last up to either 10,000 or 20,000 hours depending on the levels of stress or consistent use.

Portable unit

Generally, these units have roughly 2000 hours of run time.

F) Fuel Economy Considerations

Standby generator

Some can be fueled by the regular household natural gas supply, which may not need regular refueling or use the fuel tanks, which usually hold a considerable amount of fuel for long periods. With the right maintenance and using high-quality fuel, these tanks can run longer over a 3-day stretch. Generally, these units can be fueled by different sources of fuel for each of the different types of units; natural gas generators, propane generators or diesel generators.

Portable generator

These units are only fueled by tanks. Generally, they only hold enough fuel for a relatively short run, for 5-10 hours. This means that it has to be fueled regularly since the generator runs, and the remaining fuel must be drained after every run. Additionally, the fuel has to be stored outside. Generally, these units are fueled using gasoline as portable gasoline generators.

G) Start-Up Process

Standby generator

This type of unit needs to be connected to the electric frame, using an automatic transfer switch, which automatically starts the generator during an outage.

Portable generator

Most units in this category are manual, so with the help of a recoil pull-cord, you'll have to connect the generator to your house appliances for each run.

Liquid Propane Vs. Natural Gas Generator

Naturally, as a generator owner, your next follow-up question would be; which is better between a Liquid Propane (LP) or a Natural gas-powered (NG) generator? This will help you understand which generator is best for you and the intended purposes.

A standby NG-powered generator taps into an underground fuel line which helps give it an unlimited access to natural gas to help your generator run continuously. Since these underground fuel lines are controlled by the relevant township, you won't have to worry about filling up the generator's tank, like you would if you had an LP-powered unit. Typically, these units can continuously run for up to 200 hours without any hiccups. On the other hand, if the natural gas line you're on is damaged during any natural disaster, your fuel access is then limited or restricted.

On the other hand, the runtime of your liquid propane generator depends on your fuel tank size and the availability of the propane. Meaning that your generator might have the capacity to run continuously for a couple of days but be limited to the availability of the fuel to produce electricity until you refill up the tank. Although the specific wattage also determines how long it'll run, typically, a 1-2 gallon fuel tank will last you 8-10 hours.

So if you want a couple of days worth of backup power, you should probably go for a tank that's relatively bigger. Also, keep in mind that filled propane tanks will only hold 80% of their rated capacities, meaning a 500-gallon tank can only store 400 gallons of propane.

What Are The Wattage Requirements?

This part might seem pretty straightforward: that larger generators will require more fuel compared to the smaller ones. If you get the 11 kilowatts (kW) generator and then use it to full capacity, it's definitely going to use less fuel compared to the 20 kW unit running at full capacity. 

Also, if you're planning on powering high-wattage household appliances and a higher number of items, you'll also require way more fuel. For example, your electric water heater will need roughly 4,000 watts, while your WiFi and cable router will probably need only 40; the water heater will definitely need more fuel. Generally, the more items that need to run, the higher the wattage you need.

However, the generator comes with an operating manual that should tell you how much fuel the unit you pick will drain per hour while operating at full capacity. You can also use the information given to help you calculate how quickly you'll be depleting your tank supply.

What’s The Durability And Warranty?

The other side of the big question, "How long will your generator last?" could also mean how long will the generator run over its entire lifetime. Some generator manufacturers will offer a lifetime warranty on their units on certain parts, while others will have it cover the entire generator.

However, this level of generosity isn't so common. Hence, most reputable brands usually offer a cover with a 5-10 year warranty or at least provide a unit that should give you at least 3,000-5,000 hours. With proper care and preventative maintenance, the machine should last you a good number of years, no matter the level of use.

What’s The Level Of Maintenance?

No matter how powerful or durable the generator is, a lack of routine maintenance will decrease its useful life. Here are some handy generator maintenance tips and a few factors that influence the time you can continuously run a generator:

  • Your generator will need you to fire it up every few months to keep the electric starter's battery fresh and charged; otherwise, it may fail to run
  • Also, regularly checking for rust, check oil and inspect the belt drives, batteries, and spark plugs
  • Have an oil change every 50 hours while replacing filters
  • Have yearly check-ups on your generator

How Do You Get The Longer-Lasting Power?

This is where you hunt for the right unit. Having a new generator last in its lifespan starts with choosing the right generator, manufacturer and brand. Generally, engines with pressurized lubrication are usually more durable since the lubrication allows the oil to circulate through the engine immediately it up, keeping the engine from going cold for less wear.

Additionally, getting the most out of your unit means getting the right size generator for the home. Since a generator with a lower capacity than what you need will put a strain on the generator engine. Every time it's at or near full capacity, it puts a strain on the engine.

This engine strain thereby shortens the generator's lifespan. Overall, always take the time to calculate and determine the amount of energy the household uses to know what energy range engine you should be looking at.

Ian Mutuli

About the author

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
Related Articles
What Size Of A Generator Do I Need For Adequate Power

What Size of A Generator Do I Need For Adequate Power?

Asking the question, "What size generator do I need for my household appliances?" is a typical inquiry people make before ...

Best Portable Propane Generator: Top 8 Picks

Imagine working on an important job on your desktop and (Oops!) a power outage. How unfortunate, particularly when you have ...

Predator Generator 8750 Reviews and the Best Alternative

Generators are still at the top of the chain as alternative and backup power supply. My go-to pick has always ...