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We test electric lawn mowers by putting them all through a battery of tests (no pun intended, we actually do battery tests) and yes, we mow stuff. There are certain product categories where we have tons of data at the moment, but despite our best efforts, data alone can’t give us the full picture of which product performs best. Taking it out into the yard is the best way to filter and decipher the data we have.
Battery testing
Let’s start with those battery tests. This one isn’t too complicated, but it can be tricky to physically set up. In order to measure the voltage and amps that the mower is drawing while it’s running, we need to place our meters between the battery and the mower. The physical process varies a bit from mower to mower, but once we’re set up, we’ll get a measurement of the DC voltage and amps moving between the battery and the mower, which will give us an idea of the mower’s motor power (in watts).
We take these measurements at zero load, meaning we’re not cutting grass or otherwise applying resistance to the blades at that point, which would change the numbers, making them higher to account for the higher engine power limits. Our next round of test updates will include those higher power limits as well.
RPM testing
Yes, we absolutely measure the RPM of the blades in electric lawn mowers. The astute lab crew at CNET has developed the ability to count tens of revolutions per second with super-accuracy. I’m kidding, although we do have a meter for that. What we actually do is take a piece of reflective tape and place it on the blade of the lawn mower. We then aim the meter so that the laser light hits the tape and we get an accurate measurement of the RPM of the blades.
In the middle, under the safety glass, you can see our test meter in blue.
Now, if we combine those numbers with other numbers, like blade lengths and weights, and add in some of our engine power calculations, we can estimate things like the amount of force, in Newtons, that the blade exerts on the grass. Those numbers aren’t particularly useful. Most people have no idea what 5 Newtons of force is comparable to. We prefer to compare power output to something that people are more familiar with; in this case, horsepower.
Gas-powered push mowers vary in horsepower, but most fall in the 3- to 5-horsepower range. We’ll add the upper limit numbers in our next update, but as you can see, the lower limit in horsepower for the electric mowers we tested ranged from about 0.1 to 0.6 horsepower. That’s not a lot. In general, you should expect electric mowers to triple that number toward their upper limit, so we’re looking at about 1.75 horsepower. You’ll be hard-pressed to find gas-powered push mowers that run below 2 horsepower.
Noise level
We talk a lot about noise levels, especially with outdoor tools. Historically, these gas-powered outdoor tools were pretty loud. (Try sleeping in when all your neighbors are mowing early on the weekend.) With the advent of power tool platforms, all that changes. Your neighbor can obsess over maintaining the lawn while you sleep all day.
We tested the decibel level of the mowers from the perspective of a person operating them. We mounted a decibel meter in a fixed location and took the measurement. The results were not surprising, because our quietest mower was the smallest, the 13-inch Litheli at 68.6 dB, and the loudest was also the most powerful mower, the Ego, at 86.7 dB.
Speed tests
Normally you might think of mowers that move at a certain speed, specifically, at whatever speed you push them. More and more mowers are now coming with self-propelled options. Many of these electric powered mowers allow you to use that feature even when the blades are not spinning.
We measure how fast mowers go in miles per hour. You won’t be hitting driveways with this, but if you plan on using this mode, it can help you decide which one to choose or skip. The Ryobi had the widest range of speeds to choose from, but it wasn’t quite the fastest mower. The Ryobi topped out at 3.03 mph, while the Greenworks Pro topped out at 3.33 mph.
Some lawn mowers, such as this Cobalt model, can become blocked by grass clippings.
