Battery Equivalents and Replacements

Yamaha EF1000iS Portable Inverter Generator

Yamaha EF1000iS Portable Inverter Generator is one of the most compact, lightest, and quietest gas-powered portable inverter generators on the market.

Yamaha EF1000iS offers many features that are usually available on larger, more powerful models. Also, it is CARB compliant and may legally be used in all 50 states.

Published: February 22, 2021.

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Yamaha EF1000iS Features and Specifications

As said before, Yamaha EF1000iS is one of the most compact and lightest portable inverter generators. It features physical dimensions of (L x W x H) 17.7 x 9.4 x 15.0 inches (~45 x 24 x 38 cm) and weighs 28 pounds (~12.7 kg) and can be easily carried around via a builtin handle by a single adult.

Yamaha EF1000iS features 900 running watts and 1000 starting watts (7.5/8.3 Amps @120V) and is suitable for powering smaller home appliances, tools, chargers, and similar.

The unit is powered by a four-stroke, 50 cc single-cylinder OHV engine that uses unleaded gasoline as a fuel. Tank capacity is 0.66 gallons (~2.5 liters). The engine comes with an automatic low-oil engine shut off feature.

Thanks to the fuel-efficient engine and high-efficient electronics, Yamaha EF1000iS is able to continuously operate for 12 hours @25% load (225 watts) on a single fuel tank, which is more than enough for a 32-inch TV, small RV fridge, and a few LED lights.

When the Yamaha EF1000iS is pushed to the limit, it can power much larger devices and tools, just be aware of both starting and running watts of the appliances or tools that are going to be connected to this unit.

AC output voltage stability is 1% and frequency stability is 0.1 Hz. Also, output voltage is, according to the manufacturer, pure sine wave and 'is as clean or cleaner than public utility power' - Yamaha EF1000iS is an excellent inverter generator for powering sensitive electronics and other devices that don't operate well when being powered with high THD (Total Harmonic Distortion) power sources.

Note: Yamaha EF1000iS is easy to use and maintain power generator, but when it arrives, be sure to thoroughly read the Owner's Guide in order to get accustomed to your new power generator.

control panel

The control panel features an overload indicator light, AC light, oil warning light, engine switch, choke and fuel knobs, ground terminal, economy control switch, DC protector, AC receptacle (2x 120V), and DC receptacle (12V 8A).

120V AC receptacles are intended for powering various home appliances and tools, while 12V 8 Amps DC port is intended for charging of the lead-acid automotive, marine, and smaller industrial batteries.

Some of the interesting features include:

- Auto Warm-up automatically increases engine RPM for a few minutes during cold startups,

- Noise Block is an acoustically engineered sound reduction system that makes Yamaha EF1000iS one of the quietest inverter generators in its class. Nominal noise levels are 47 dBA @25% load and 57 dBA @100% load, measured from the distance of 23 feet (~7 m).

- Economy mode and Smart Throttle automatically adjust the engine's RPM, saving fuel and prolonging the maintenance intervals.

- Dual coil alternator stator provides more power at lower RPMs, reducing noise, fuel consumption, and engine wear.

Of course, there are other features present, some of them are practically standard for modern portable inverter generators, and others are found at larger units.

Also, there are few things missing, but would be nice to have:

- Yamaha EF1000iS is not Parallel Ready inverter generator - two units cannot be connected in parallel in order to increase the output power. This is even logical since Yamaha EF1000iS is far from being the cheap model and people requiring more power should go for a stronger model.

- by default, Yamaha EF1000iS doesn't feature an hour-meter and tachometer and it should be ordered separately - such a device can be very helpful in monitoring the unit and when planing the maintenance. It can be ordered using Yamaha ENG-METER-4C-01 Hour/Tach Deluxe Engine Meter Amazon link (link opens in the new window).

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- adding oil must be done very carefully or some oil spilling may occur.

There are also some other minor details, that these are really - minor. Except for the price, which is - not minor :) But, what You pay is what you get.

Yamaha EF1000iS portable generator comes with a 3-year residential warranty and a 2-year commercial/industry warranty.


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Long Story Short: Yamaha EF1000iS is a reliable and durable 900/1000 watts portable inverter generator. It is very quiet unit, well liked by its owners.

It is suitable for camping, fishing, tailgating, and other outdoor activities that don't require larger and more powerful generators.

For more reviews and recommendations, feel free to follow Yamaha EF1000iS Portable Inverter Generator Amazon link (link opens in the new window).

Amazon Search:

- Inverter Generator

- Portable Inverter Generator

- 2000W Inverter Generator

Note: Amazon links open in the new windows, feel free to check them for the most up-to-date offers and prices.