Ultimate Guide to Generators

Many people think of generators as just a backup for powering your home in case the power goes down, but they’re good for so much more than that.

Having a portable generator can allow you to keep the comforts of home far beyond your home’s power outlets, or to power tools and devices in your yard or at a worksite.

More important, a generator is reliable. You know that no matter where you go, you’ll have power from your generator.

In this guide, we’ll cover everything you need to know about generators. From choosing the generator that will cover your power and portability requirements to how to set up and maintain your generator for optimal performance, we’ve got you covered.

If you want to dive right into our buying guides for each type of generator, you can find them here:

Why Use a Generator?

Let’s start off by answering a basic question – why bother with a generator in the first place?

The advantage to using a generator is that it provides portable power so you can take your electronic appliances, tools, and devices anywhere off the utility grid.

There are a virtually infinite number of reasons to use a generator, but let’s take a look at some of the most popular ways that people put their generators to work:

  • Emergency backup power for your home’s essential appliances in case of a power outage
  • Portable power source for appliances in your RV when you’re not at a full-utility campground
  • Field energy source for running power tools at a worksite
  • Small power source for bringing the amenities of home to your campsite
  • Portable energy for running lights, speakers, and more at outdoor events

Chances are, you can think of at least one scenario in the recent past when having a portable power source would have made your life significantly easier.

Better yet, while different types of generators are more suited to specific purposes, most generators can be used for any combination of these uses.

In addition, just having a generator can provide peace of mind. While no one likes to think about power outages, they do happen – especially during severe weather events. Having a generator on hand can prevent losing access to all of your home’s appliances for hours or even days.

How Much Power Do You Need?

It’s important to think about how you might use your generator because it leads us to one of the most commonly asked questions about generators: how much power do you need?

Thankfully, this is a straightforward question to answer if you know how you plan to use your generator.

Every appliance and tool requires a certain amount of wattage to run – you should be able to find this information in the manufacturer’s instructions.

If you expect to plug several appliances into your generator at the same time, the amount of power you need will be at a minimum the sum of the wattages of all those appliances.

There are a few catches to this guideline, though.

The first is that motor-drive appliances have what’s known as a surge wattage requirement. This is an extra-high wattage requirement that kicks in during the first few seconds of use, as the motor is starting up. All generators thus offer a surge power rating, which is the power they can output for a few seconds to help motor-driven appliances get going.

The second catch is that you don’t necessarily want to run your generator near it’s maximum wattage 100% of the time. Instead, after you add up the running wattages of all the appliances and tools you want to plug in, give yourself some leeway in the power of your generator.

The main reason for this is that running the generator near its maximum power all the time can dramatically increase wear and tear on the engine. In addition, the closer your generator is running to its maximum output, the louder it will be and the more quickly it will run through fuel.

Estimating Wattage Requirements

If you’ll be using your generator for multiple purposes, don’t yet own all of the appliances you expect to use with your generator, or aren’t quite sure how you’ll use your generator just yet, don’t worry. There are several ways to estimate how much power you’ll need in a generator.

If you’re planning to use your generator at home or to power an RV, there are a number of online calculators that estimate your wattage requirements.

As a more general rule of thumb, a 2,000-watt generator is typically good for a campsite, a field worksite running a handful of smaller tools, or for powering tools around your yard. For more information, check out our guides on the Best Generator for Camping and the Best Generator for the Worksite.

A 3,000-4,000-watt generator provides enough power to keep all of the essential appliances in your home running during a power outage. It’s also handy for powering an RV with a small air conditioner – check out our guide to the Best Generators for your RV.

Larger generators, which can range upwards of 10,000 watts, are typically reserved for large worksites, very large RVs, or for powering your home without a hitch during an extended outage.

Conventional vs. Inverter Generators

If you’re looking for a generator that provides 4,000 watts or less, you’ll need to decide between a conventional portable generator and an inverter generator.

Conventional generators are the standard portable generator that were ubiquitous in your parent’s generation. They work well and are extremely reliable, but they come with a lot of complaints about noise and aren’t suitable for todays suite of appliances, tools, and other electronic devices that are controlled by microprocessors.

Inverter generators, on the other hand, are safe to use with any sensitive electronics – including your smartphone and computer.

The most significant different between conventional and inverter generators is in how they “clean” the electricity they produce.

Both types of generators produce AC power from the engine. But whereas conventional generators output that AC power directly, inverter generators convert it to DC and then back to AC power. In the process, the electrical waves are smoothed out, resulting in total harmonic distortion values of 3% or less in most cases.

Beyond being able to power small electronics, there are a number of other advantages to inverter generators.

The first is that they are significantly quieter than conventional generators. Whereas with many conventional generators you’ll need to shout to have a conversation, with an inverter generator you can easily hold a conversation while standing over the generator. That’s why all of the Quietest Generators we reviewed are inverter generators.

The second advantage is that inverter generators tend to be more lightweight and portable than conventional generators. Almost all inverter generators also have a fully enclosed engine, which means you won’t scald yourself on a hot engine component while moving the generator around.

Third, inverter generators can be connected in parallel. That means if you have two of the same model, you can link them to double your available power output through a single outlet.

Finally, inverter generators are more fuel efficient than conventional generators.

So, if inverter generators are quieter, more compact and lightweight, and more fuel efficient than conventional generators, why is there a choice at all?

Well, as you might expect, inverter generators come at a price premium. The prices aren’t extreme, but also factor in that repairing inverter generators is more expensive because there are a lot of electrical components around the engine that aren’t present in conventional generators.

The second factor is power. At the moment, the most powerful inverter generators top out at around 4,000 watts of surge power. So, if you need more power than that, you’ll either need to pair inverter generators in parallel or switch to a conventional generator.

If you’re interested in learning more about inverter generators, check out our guide to the Best Inverter Generators.

What Type of Fuel is Best?

When it comes to fueling your generator, gasoline is the standard – but it’s far from the only option.

Choosing the best fuel ultimately comes down to how you’ll be using your generator and what fuels you’ll have easy access to.

The most common variation on the standard gasoline generator are dual fuel generators. These generators run on either gasoline or propane, and many can be switched between the two fuels without even shutting off the engine.

In contrast to gasoline, propane can be easily stored for months or even years. That makes it an ideal candidate for stockpiling fuel if you’re worried about an extended power outage at home.

There are few downsides to dual fuel generators except the added upfront cost. But since propane is cheaper than gasoline, opting for a dual fuel generator could end up saving you money in the long run.

If you’re interested in a dual fuel generator, check out our guide to the Best Dual Fuel Generators for more information.

Taking the fuel adaptability one step further, tri fuel generators add natural gas into the fuel mix. Natural gas is the least efficient of the three fuels, so you’ll lose some power output from your generator when running on natural gas.

But, if you have a natural gas line running to your home, you can use it to power your generator during an extended power outage. That’s because gas lines continue to run during most power outages, as long as the underground lines aren’t damaged.

Our guide to the Best Tri Fuel Generators covers these generators in more detail, including how to convert your existing generator to a tri fuel generator.

Finally, diesel generators can last tens of thousands of hours with minimal maintenance without breaking down. However, diesel generators are relatively uncommon because they are much noisier and more expensive than standard gasoline generators.

If you think the durability of a diesel generator might be right for you, you can learn more about them in our guide to the Best Diesel Generator.

How Loud are Generators?

Generators have a reputation for being loud, although that reputation is fading away thanks to the new class of inverter generators.

Inverter generators that produce in the range of 2,000-3,000 watts of power typically put out about 50 dB of noise at 25% load – the same low level of noise produced by a conversation.

However, keep in mind that for any generator, the amount of noise produced will increase as you run it closer to its rated power output. For inverter generators that start at 50 dB, they may produce upwards of 60 dB at full power – 10x louder and producing about the same amount of noise as a car going by on the road.

Conventional generators and significantly larger generators can be much louder – upwards of 70 dB – so be careful if you plan to use your generator at night or at a campsite.

For more information and to find a generator that won’t blow out your eardrums, check out our guides to the Quietest Generators and the Best Generators for Camping.

Electric and Remote Starting

One of the modern conveniences that is being added to more and more generators is a push-button electric start. This is designed to replace the old pull-cord start, which used to be notoriously hard to start.

In addition, some manufacturers have taken this convenience even further by adding a remote start function. That way, you can start up your generator without leaving the comfort of your home, RV, or tent.

However, keep in mind that electric and remote starting generators rely on an on-board battery. That battery can die if it’s not charged every once in a while, which is why most electric generators come with a backup pull-cord starter.

If the convenience of an electric or remote starting generator appeals to you, check out our guide to Remote Start Generators.

CARB Certification

If you live in California or plan to travel there with your generator, you’ll need to consider one other factor when choosing a generator – whether it is certified by the California Air Resources Board (CARB).

This regulatory agency sets a stricter standard for engine emissions than the EPA, which is why not all generators are certified by CARB.

Any generator that isn’t CARB-certified can’t be bought in California.

Checking for CARB certification is still worthwhile even if you don’t live in California, though. The agency’s stamp of approval is a good sign that a particular generator produces less smoggy exhaust than non-CARB-approved generators.

Maintaining Your Generator

Generators can last for decades if treated properly.

The most important maintenance step you can take to protect your investment is to change the oil. Generator engine oil should be changed out after the first 30 hours of use, and then every 100 hours after that.

On top of that, it’s important to remember to never leave stale gasoline in the fuel tank. Gasoline goes bad after a few months of exposure to air, and running old gasoline through your engine is a sure way to damage it.

That means that before storing your generator for the winter or any other extended period, you’ll need to empty out the carburetor. Some generators have a built-in function to make this easy, while others require that you run the generator until the fuel is exhausted.

If you can, running the generator once every month or so will keep the internal engine parts lubricated.

There are also a couple important points to keep in mind when operating your generator.

First, whenever refueling your generator, you need to let it fully cool down first. If you add gasoline while your generator is still hot, you risk sparking a gasoline fire that could be extremely dangerous to both you and your generator.

Second, keep in mind that running your generator dry frequently or overdrawing on power can damage the engine. Pay attention to the wattage requirements of whatever you’re plugging into your generator, and make sure to plug in any appliances that have a surge requirement first.

Third, remember to keep your generator’s battery charged if you have an electric starting generator. Otherwise, you’ll need to revert to the backup pull-cord start or you may not be able to use your generator.

How to Connect Generators in Parallel

If you have two or more units of the same inverter generator, you can double the power available through a single outlet by connecting them in parallel.

To do this, you’ll need a parallel connection kit sold by the manufacturer of your inverter generators. Note that because of the computers inside inverter generators, you will specifically need two generators from the same manufacturer and the specific parallel connection kit from that manufacturer – no mixing and matching!

With the kit, you’ll connect the two generators through the parallel connection outlet, which is typically in the main outlet panel. Once the generators are connected, turn them both on and plug your large appliance into either generator to start running it.

How to Connect a Generator to your RV

Connecting a generator to your RV is easy if your generator has a 30-amp RV-ready outlet. These three-pronged outlets are specifically designed to connect to your RV’s 30-amp inlet using a transfer cord from any manufacturer.

However, if your generator has a 120-volt/240-volt twist-lock outlet instead of an RV-ready port, you’ll need either an adapter or a transfer cable that is designed to work with this type of outlet.

If your generator doesn’t have either of these, unfortunately you won’t be able to connect directly to your RV’s 30-amp input. Instead, you’ll have to run the power cords from the appliances inside your RV directly into the 120-volt outlets on your generator.

How to Connect a Generator to your Home

The easiest way to connect a portable generator to your home’s appliances is to simply run extension cords from your appliances to the generator. This solution is relatively fast, inexpensive, and simple, although it can become cumbersome for longer or frequent power outages.

If you want to be able to connect your generator to your home’s power grid, you’ll need a transfer switch. These can be somewhat costly and, depending on your electrical experience, you may need an electrician to wire it into your existing circuit breaker.

If you have a transfer switch set up, you can simply connect your generator’s 120-volt/240-volt outlet to the transfer switch. Turn the setting on the transfer switch from “line” to “generator,” power up your generator, and then turn the circuits you want to power on one at a time.

Frequently Asked Questions

What happens if the generator is overloaded?

Overloading the generator happens sometimes, especially if your generator doesn’t have a built-in voltmeter.

In that case, depending on the construction of your generator, the engine will either automatically shut off or a circuit breaker will trip.

If your generator has a built-in circuit breaker, you’ll likely need to reset the breakers using switches on your generator’s outlet panel. If specific outlets don’t have a reset button and there is no main breaker switch, you’ll need to turn the generator’s engine off to reset the system.

How long will a generator run on a full tank of gas?

The runtime of a generator can vary greatly between generators and is a result of the fuel tank size and the engine efficiency.

Most generators have their runtime rated based on a 25% or 50% power load, and runtimes can range from just a few hours to 15 hours or more.

Runtime is an important consideration in choosing a generator, especially if you are planning to use your generator for extended periods. Keep in mind that your runtime will change depending on how close you are running the generator to its rated power output.

What type of oil do I need for my generator?

Changing your oil after every 100 hours of use is an important part of maintaining your generator.

Most generators use 5W-30 or 10W-30 synthetic oils. However, be sure to check your manufacturer’s recommendations for your specific generator.

Do generators come with a warranty?

Most, but not all, generators come with a warranty from the manufacturer. Warranty policies can vary in length from less than one year to three years or more, so be sure to check before purchasing a generator.

In addition, keep in mind that almost all warranty policies are “limited” and may not cover all types of damage to your generator.

Conclusion

Having a generator can allow you to keep your home up and running throughout a power outage, power your RV or camping adventure, or provide a portable energy source for worksites and outdoor events.

With all those uses of generators in mind, it’s important to choose a generator that will fit your needs and be versatile enough to adapt as your uses change.

For more information on each type of generator and to find the best generators for specific purposes, check out our comprehensive series of buying guides.

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