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A portable generator is a smart investment anytime you need extra power or during an emergency. Capable of running small appliances, lights, and other devices, power generators make it easy to stay connected in places where you might need some extra juice.
The choice of the right portable generator mostly comes down to your power needs. How do you want to use the generator? Is it for emergencies or camping? What devices will you power? Generators come in different wattage ratings; the higher the rating, the more power it produces. Many devices like small home appliances require higher ratings for adequate power or consistent use.
Are you looking for a “rescue” generator because you suffer power outages at home? Are you looking for a portable generator for camping or RV trips? Do you need something to run power tools at a site with no electrical supply?
It's the big question, but finding the answer isn't always straight-forward – and often we expect a portable generator to fill more than one role.
Let's look at power consumption first, to get a better idea of what the portable generator must do.
If you go around your house and make a quick inventory of electrical consumption, you'll soon realize that the even biggest portable generator can’t run everything at once.
An average home has power demands of 10,000 to 20,000 watts. If you want to run everything you need a permanent stand-by generator, hard-wired by a professional. It's the kind of thing that will cost you anywhere from $2,000 upwards.
A portable generator gives you back-up power until the normal supply is restored. Depending on the size it can run much more than just basic necessities. If it's intended for work or recreational use there are other calculations to be made, but the same principle applies. Here are a few common items that will give you some idea. You can do your own math easily enough: every electrical gadget you own should have the wattage demand marked on it somewhere.
Lamps need 60 to 120 watts.
A sump pump needs 750 to 1,500 watts.
A refrigerator needs 500 to 750 watts.
Computers need 60 to 300 watts.
Heaters need 500 to 1,500 watts.
A coffee machine needs 750 to 1,000 watts.
Halogen work lights need 300 to 600 watts.
An electric drill needs 500 to 900 watts.
There's another important consideration when looking at power consumption. Most electric devices have greater demand when they're initially turned on – it's called “surge.” It can be anywhere from 2 to 5 times the normal operating demand. That's why you see portable generators rated at, for example, 3,300 running watts and 4,000 starting watts. The latter is the surge it's capable of handling.
The important thing to note here is that surge lasts a few seconds at most, and you don't have to start all your electrical gadgets at once.
To manage surge, turn on your lights, wait a moment, turn on your refrigerator, and so forth. That way you don't get them all surging at once and causing an overload.
Most portable generators are broadly similar and use either a gasoline motor or a propane motor to change mechanical energy into electricity.
Portable inverters use the same basic principle but, thanks to special mufflers, fuel injection and other clever tricks, they are smaller, lighter and a lot quieter. This makes them ideal for recreational use: outside parties, camping, tailgating, and RVing. They often feature automatic power fluctuation controls, making them especially good with sensitive electronic devices.
There are two drawbacks to inverters. First, power output is lower – generally between 1,000 and 3,000 Watts. Second, they are relatively expensive.
OK, you know how much power you need, but how long will your portable generator run? Can you leave it all day, or will you have to refill the gas tank every few hours?
Portable generator manufacturers are happy to quote run times, but you have to be careful. Seldom, if ever, will the advertised figures align with the generator running at full capacity. You'll see things like “12 hours at 1/4 load,” or “8 hours at 50% capacity.”
To be fair, portable generators hardly ever run at peak performance for very long, so it's not that the manufacturers are being deceptive, though they are showing things in the best possible light!
You also have to consider the wattage you're consuming. Ten hours at 50% from a portable generator delivering 3500 watts is not the same as 10 hours at 50% when the power you're using is 7,000 watts.
Each of the portable generators we've chosen runs on gasoline. Liquid propane is an alternative, and there are plenty of models that use it. The main reason none of these made our final selection is simply fuel storage.
The biggest tank among the gas-powered units we’ve selected is 7.5 gallons. A similar propane model requires several 20 lb. tanks to run for the same period.
Not only do you have to have the space to store them, you need to change them over more regularly.
Deciding how much power you need will focus your choices, but there are still many portable generators vying for your money. Here are some of the features you will want to look for.
If it has a ripcord, the generator should offer decompression for easy starting. The best portable generators do away with a cord completely – you just turn a key or push a button.
It's nice to be able to check levels without taking the filler cap off.
Running low on oil can seriously damage your equipment.
Units equipped with throttle sensors can adjust performance depending on load, thus increasing fuel efficiency and run time.
Wheels are a separate accessory with some portable generators. Portable inverters aren't designed to have wheels, and it's not a problem when the unit only weighs 45 pounds or so. However, when a model weighs 90 pounds plus, wheels are something of a necessity.
Depending on the model, you'll get one or more 120V AC outlets. You might also get a DC outlet (useful for charging batteries), a specific RV outlet that you can plug directly into your RV's electrical circuit, or a 120/240V 30A (also called twist lock) that may be compatible with transfer switches.
Transfer switches, which should be installed by a suitably qualified professional, allow you to plug your portable generator directly into your household electrical supply, so you only run a single cable, rather than trying to run a number of extension cords through doors or windows.
You’ve probably heard it a thousand times, but in this case it's particularly important: always read the manufacturer's instructions! First, fumes from generators are dangerous. Second, if you fail to look after your portable generator and maintain it properly, it might let you down when you most need it.
The following might be covered within those instructions, but are worth underlining:
Manufacturers recommend a minimum of five feet of clear space on all sides of your generator when it's running.
It should always be run outdoors. A garage or shed with the door and windows open is NOT outdoors. Carbon monoxide can build up in enclosed spaces. It's colorless, odorless, and lethal.
Never fill the gas tank when the portable generator is hot. Spilled gas can ignite on a hot exhaust or casing. It's almost invisible, so it can burn you, or things around you, before you realize.
Never completely fill the gas tank – always allow room for expansion.
After use, never put your generator away until it is completely cool.
Never attempt to wire your generator into a household socket. “Back feed” can cause electrocution or fires not just in your home, but anywhere in the local network. If you want the option of a fixed connection, ask a properly qualified professional to install a transfer switch.
Beware of overloading your portable generator. If in doubt, consult an electrician.
Check that your generator is properly grounded. Follow all applicable federal, state and local regulations related to grounding. If you don't, you risk being electrocuted.
During our research we found cheap portable generators for as little as $100. We don’t recommend generators at that level, but they do exist.
Our five finalists are all highly-rated models that receive lots of positive feedback from owners. They're also representative of what we would consider 'best in class', in terms of price and performance.
With portable generators, you pretty much get what you pay for.
A robust, reliable entry-level machine can be yours for under $300. That's a great deal, but we recommend spending another hundred bucks or so for a model with similar power output, but a more exhaustive feature set.
Need to go big? Our more expensive selections get you significantly higher power output, along with excellent reliability.
Inverter generators are a slightly different story because they generally cost more than their “standard” counterparts. The model we recommend is close to a thousand dollars but, in our view, unbeatable in its class.
