We test our electric lawn mowers by running each one through a series of tests (we’re not kidding, because we run real battery tests). Yes, we also mow the grass. We collect large amounts of data for certain product categories, but despite our best efforts, data alone does not provide a complete picture of which products perform best. Taking these into the garden is the best way to help filter and decipher the data we have.
battery test
Let’s start with the battery test. This isn’t too complicated, but it can be a little difficult to physically set up. To measure the voltage and amperage that the lawn mower draws during operation, you need to insert a measuring device between the battery and the lawn mower. The physical process is a little different depending on your mower, but once set up, you’ll get a reading of the DC voltage and amps traveling between the battery and the mower, and the mower’s motor power (in watts). I understand.
These measurements are taken at zero load. This means that at that point you are not cutting the grass or creating any resistance to the blade, so the number changes and becomes higher to calculate the upper limit of the motor’s output. The next test update will also include these power caps.
Rotation speed test
Yes, we always measure the rotational speed of electric lawn mower blades. CNET’s observant research staff has developed the ability to count dozens of revolutions per second with ultra-accurate methods. Just kidding, there is a meter for that. In practice, you take a bit of reflective tape, place it over the mower blade, aim the measuring tool so that the laser beam is over the tape, and get an accurate reading of the number of revolutions of the blade.
You can see the blue test meter in the center under the safety glass.
Now, if you combine these numbers with other numbers such as blade length and weight and add motor power calculations, you can estimate things like the amount of force (in newtons) the blade will exert on the grass. These numbers aren’t very useful. Most people wouldn’t really understand what 5 newtons of force is equivalent to. We choose to compare the output to what people are familiar with. In this case, it’s horsepower.
Gas-powered push lawn mowers vary in horsepower, but most are in the 3-5 horsepower range. We’ll add a higher end number in the next update, but you can see that the lower end of horsepower for the electric lawn mowers we tested ranges from about 0.1 to 0.6 horsepower. I mean, there aren’t that many. We’re assuming 1.75 horsepower, since electric lawn mowers are generally expected to triple in number towards that top end. You would be hard-pressed to find a retail gas-powered push mower that operates on less than 2 horsepower.
noise level
We talk a lot about noise levels, especially with outdoor tools. Historically, these outdoor gas-powered tools were very noisy. (Try to sleep on the weekends when your neighbors are mowing early in the morning.) The advent of power tool platforms changed everything. While you snooze, your neighbor might be busy tending to their lawn.
We tested the decibel level of lawn mowers from the perspective of the person operating the mower. Fix the decibel meter and measure. The results weren’t too surprising, with the quietest mower being the smallest, the 13-inch Litheli, at 68.6dB, and the loudest being the most powerful mower, the Ego, at 86.7dB.
speed test
Typically, you might think that a lawn mower moves at a certain speed, specifically the speed you happen to be pushing it. More and more lawn mowers now have self-propelled options. Many of these electric lawn mowers allow you to use their features even when the blades are not working.
Measures how fast the mower is moving in miles per hour. You won’t be using these to visit the entrance ramps, but if you plan on using this mode, this may help you decide which one to pick up or pass through. The Ryobi had the widest range of speeds to choose from, but it fell just short of the fastest mowers. The Ryobi topped out at 3.03 mph, while the Greenworks Pro topped out at 3.33 mph.
Some lawn mowers, like this Kobalt model, can get stuck in grass clippings.
