## July 27, 2009

### How Much Does It Cost to Operate an Electric Lawn Mower?

I previously estimated that I save \$8 a year by using an electric mower rather than a gasoline mower. That estimate was figured when gasoline was about 50% higher than it is now so the number has dropped since then. When I did that estimate I did not have a hard number for the amount of electricity my mower actually uses. At the time I used an estimate of 0.5 kWh. But I decided to answer the question : How much electricity does it really cost me?

First a couple basic facts: I currently have a Black & Decker CMM1200 19-inch 24V cordless mower. The mower runs on a battery that you charge by plugging it in. I'm not really sure exactly how big my lawn is. I'd estimate that there is around 4000 to 5000 square feet total. But thats a fairly rough guess.

I used a Kill-a-Watt monitor to measure how much power my mower was using while it charged the last couple times. The Kill-a-Watt can see the Watts, Amps and accumulated kWh used. I used 0.28 kWh for the first mowing and 0.22 kWh for the second mowing. Thats an average of 0.25 kWh across the two. Our electricity is 10-11¢ so that means I spent around 2.5-2.75¢ in electricity for each of the two mowings.

I think its a pretty safe bet that a typical 19 inch electric mower is going to cost about the same amount to run. Electric motors are fairly standard and there is not much of any difference in how they operate from one model to another. May mower may be a bit more or less powerful that other models. There may be some minor variation but you're probably looking at 2-4¢ for a lawn my size. Plus how fast or slow you are when you mow the lawn will impact it some. If you walk faster you'll be mowing faster and operate the mower for less time.

I'd estimate that it is roughly 0.5 to 1¢ per 1000 sq foot to operate a typical 19" electric lawn mower.

To get a better approximation of your own costs you can use the do the math using your own figures for electricity cost and the size of your lawn:

cost of electricity to mow lawn = .25/4500 x cost per kWh x size of lawn in sq ft