Noise, Runtime and Weight: What the Specs Mean in Daily Use

Three numbers on a spec sheet shape your daily experience more than any others: decibels, runtime and weight. Each one has a catch that is worth knowing before you buy.

Noise

Noise is measured in decibels (dB). The scale is logarithmic, so every 10 dB sounds roughly twice as loud. For reference, normal conversation is about 60 dB, a vacuum cleaner about 70 dB and a lawn mower about 90 dB.

Two catches apply. First, makers usually measure noise at a set distance, often around 23 feet, and at a light load, often 25 percent. Closer to the unit, or under heavy load, it will be louder. Second, many campgrounds and neighborhoods have noise limits, so check your rules. Inverter models typically run around 50 to 65 dB, open-frame models often 65 to 80 dB, and power stations are close to silent apart from a cooling fan.

Runtime

For gas generators, the advertised runtime is nearly always at 25 percent load. At full load, it can be half that or less. Read the fuel tank size and the runtime at both 50 percent and 100 percent load when the maker lists them.

For power stations, use this rule of thumb. Inverters lose some energy as heat, so real runtime is about 85 percent of the ideal:

A 1,000 Wh unit powering a 100 W load runs about 8.5 hours. The same unit powering a 1,000 W load runs about 50 minutes.

Weight

Weight decides whether you can move the generator without help. Approximate ranges:

Also check the unit's wheels and handles, and remember that you must lift or roll it into position, often over uneven ground, in bad weather.

A quick checklist

• Is the noise rating given at full load, or only at 25 percent?
• What is the runtime at 50 and 100 percent load?
• Can you lift or roll it to where you will use it?
• Do your campground or neighborhood rules set a noise limit?

The watt ratings behind these numbers are covered in watts explained.