The Yamaha EF2000iS inverter provides a stable current that's safe for electronics, but not a lot of it; it offers just 1,600 watts continuous or 2,000 peak wattage. You can daisy-chain two of these inverters together for more power. Owners say the EF2000iS starts easily and is easy to use, and it meets California's stringent emissions requirements.
Clean, stable power. Like all inverters, the Yamaha EF2000iS provides power that's safe for delicate electronics by first generating conventional AC power, then converting it to DC power before inverting it back to a stable flow of AC electricity. But with a continuous rating of just 1,600 watts and a peak or surge rating of 2,000 watts, the EF2000iS is best for powering just the essentials. You can, however, daisy-chain two units together to net more power. One Amazon.com poster who did this says the two inverters produced enough power to run his air conditioner at high speed.
Owners say one inverter on its own can power the basics such as a heater, full-size refrigerator and TV/cable box. A user writes at Cabelas.com that the EF2000iS even ran a Dometic 13,500-BTU air conditioner at sea level, although you might not want to assume that kind of performance, especially at higher altitudes.
Another Cabelas.com poster says he tested the EF2000iS and found it could run any of three portable air conditioners between 7,000 and 9,000 BTU or an 18-cubic-foot refrigerator separately, but not simultaneously. Others use it for applications that demand a highly portable inverter, like tailgating or powering fishing lights on boats.
Just the basics. The Yamaha EF2000iS comes with only the basic plug-ins you'd expect from an inverter of this size: two 5-20R AC outlets and a single DC outlet. It also has a battery cable.
Quieter than a microwave. Yamaha estimates the EF2000iS's sound level at 51.5 to 61 decibels, but doesn't give details about load or distance. An owner with a decibel meter says it measures 80 decibels -- as loud as a garbage disposal -- from 4 feet away under an 800-watt load. Readings of 58 to 60 decibels from 30 feet away are more consistent with the manufacturer's numbers; that's about as loud as a normal conversation.
The editors of Camping Life say the Yamaha EF2000iS is a little quieter at idle than its competitors in one comparative test, with several reviewers adding that you can still talk normally. "We had it about 15-20 feet away and it did not disrupt our conversation. During heavy load it does ramp up and is significantly louder but still tolerable," says one owner at Amazon.com. The Honda EU2000i (*Est. $1,000) is still quieter under load, reviewers say.
Very fuel-efficient. In a comparative test, Camping Life editors call the Yamaha EF2000iS "just as smooth and more fuel-efficient than the Honda [EU2000iS]." The manufacturer estimates 10.5 hours of runtime at one-quarter load, from a 1.1-gallon tank of gas. One owner posts similar results at ElectricGeneratorsDirect.com, saying he got about seven hours of runtime while using this inverter at more than a quarter of its capacity.
Starts on the first pull. Because the EF2000iS doesn't have an electric start, you'll need to yank a ripcord to get it going. However, most owners say they don't mind because it almost always starts on the first pull. The editors of Camping Life praise the Yamaha for its simple start process. They also like the fuel petcock that makes it easy to run the carburetor dry for storage, and its wide fuel neck. They're less thrilled with the engine cover's two tiny screws.
Weighing 44.1 pounds, this inverter is easy to maneuver; one woman posting to Cabelas.com says it's "light enough for one person to move, although a bit awkward to carry." The EF2000iS is backed by a three-year warranty, and few users comment about it needing to be serviced.
1. Camping Life Magazine
Review Credibility: Very Good Camping Life tests and compares three portable inverter generators: the Generac iX2000, the Yamaha EF2000iS and the Honda EU2000i. Reviewers connect each generator to appliances to assess operating smoothness, noise level and fuel consumption. They also consider weight and ease of use. Although this review lists pros and cons for each model, the Yamaha is singled out as the best value.
Review: Editors of Camping Life, Portable Power, June 2, 2011
Review Credibility: Good About 80 owners post reviews of the Yamaha EF2000iS, giving it an average rating of 4.7 stars out of 5. Most have only good things to say, praising the Yamaha's ease of use and how quiet it is. Several are surprised at its power. One writes, "It is expensive, but the build quality is excellent and 500-hour engine life means my beer will stay cold and my wife can dry her hair when the power is out."
Review: Yamaha EF2000iS Portable Generator, Contributors to Cabelas.com, As of November 2012
3. Electric Generators Direct.com
Review Credibility: Good The Yamaha EF2000iS gets a perfect score of 5 stars out of 5 from nearly 70 owners. One writes, "My wife and I live off grid…. In September 2009, we bought our first EF2000is. Despite the heavy use it's had -- and a bit of unfortunate abuse due to my carelessness -- it's been running now for an average of 20 hours per day for more than 17 months...and it's still going."
Review: Yamaha EF2000iS - 1600 Watt Inverter Generator, Contributors to ElectricGeneratorsDirect.com, As of November 2012
Review Credibility: Good The nearly 140 owners who post ratings here give the Yamaha EF2000iS an average score of 4.7 stars out of 5. They list very few complaints, although one says the fuel gauge on his unit didn't work and he had trouble getting it repaired.
Review: Yamaha EF2000iS 2,000 Watt 79cc OHV 4-Stroke Gas Powered Portable Inverter Generator, Contributors to Amazon.com, As of November 2012