Portable generators can be a great convenience for some people and an absolute necessity for other people.  Generators produce electricity from a separate fuel source.  Most portable generators run off standard automobile grade gasoline, although there are also generators that use diesel or natural gas.  Generators are commonly used as a backup power source when your house power fails and as portable sources of power where it is not normally available (campsites, RV’s, etc).

Wattage

Wattage is a function of voltage multiplied by amperage.

The formula is as follows:  Watts = Volts x Amps

The power draws of electrical devices may be given in either watts or amps.  If the draw is given in amps, you can convert it to watts simply by multiplying the amps by the volts (usually 110V or 120V for a standard household plug).  Some devices have a separate measure for rated wattage (also known as running wattage or continuous wattage) and surge wattage (also known as peak wattage).  The rated wattage is the power draw of a device as it normally runs.  The surge wattage is a short burst of power draw that a device requires, usually as it starts or stops its motor.  The total running wattage of the devices you intend to run on the generator should not exceed the rated wattage of the generator. To calculate the total running wattage of your devices, just sum up their individual rated wattages.  Here are the wattage requirements for some fairly common electrical devices (note that this is just a general guideline and your individual device draw may vary):

Noise Level

The noise level of generators is measured in dBA (decibels with A-Weighting) at a certain distance away (usually from 7 meters or 21 feet away from the source).  Generator noise levels typically range between 55 dBA to 85 dBA.  Fairly quiet generators are usually rated below 75 dBA.  Generators above 75 dBA are louder than usual.  For comparison purposes, here is a chart of various sound levels:

Knowing the noise level rating of a generator can be especially important if you plan on using it at a campsite.  Many campsites now have noise level restrictions to help maintain the ambience and experience for other campers, so your safest bet would be to find one under the 75 dBA threshold.  Also, you want to look for a generator with a spark arrestor (mechanism that prevents sparks or burning embers from escaping through the exhaust), as small sparks could potentially lead to huge fires.  In general, the larger the generator is (in terms of the motor’s horsepower rating, as well as the power output), the higher the noise level of the generator is going to be.

Size and Portability

In determining which generator would work for you, you should consider the physical size of the generator and its portability.  If you intend to move it around often, such as for campsite use, you may want to look for a smaller overall generator.  If the unit is for backup home power use where the unit will not be moved around often, a larger unit may be fine.  For use as a RV backup unit, the size of the available space in the RV would determine the maximum size of the generator used.

Wheels and/or a handle kit are sometimes included with generators.  Wheels are mounted to one end of the generator frame, while a peg stand is mounted to the other end.  This allows the generator to be tilted by one end and to be pushed around on its wheels

Handles are often attached to the top of the generator frame above the peg stand end.  This enables easy gripping and moving of the generator.  If available, you want to get a unit with wheels and handles for the sake of mobility and less physical strain trying to carry the entire unit around.

Starting Mechanism

Portable gas generators are started using one of two methods – recoil start or electric start. 

Recoil start (also known as pull start) involves pulling on a pull cord, much like the process involved in starting a gas lawn mower.  Depending on your physical strength and the quality of the recoil starter, the generator may take a few pulls to start up.

Electric start usually involves turning a switch or key and drawing power off of a battery to start the generator, similar to starting a car.  The obvious advantages of an electric start over a recoil start are the convenience and ease of use – it’s so simple, a child could start it.  One note about electric start, though, is the battery needs to stay charged, so you’ll need to start the generator once in a while to keep it charged.  Some electric start generators have recoil start available as a backup in case the battery is drained.