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Cordless electric lawn mowers provide a clean and quiet way to keep your lawn looking amazing. The Black Decker CM2040 cordless mower is an affordable cordless mower that offers enough power for smaller lawns with a medium thickness. It’s also interesting to note that Black+Decker is the inventor of the first portable electric drill with pistol grip and a trigger switch. The company evolved from a small machine shop located n Baltimore to a global manufacturing powerhouse that boasts a vast range of quality products that are used around the home.


Lightweight machine

The lawn mower comes with an orange housing and a black 20-inch cutting deck with streamlined dimensions. It weighs 43.5 pounds, and it’s very light compared to other models of gas-powered mowers.

AutoSense technology

The AutoSense technology determines the thickness of the grass, and it automatically makes power adjustments according to it. For example, for thicker grass, the mower will kick into high power mode, and for grass that is lighter, the mower will lower its power output to conserve the battery life and to extend runtime.


The machine comes with a convenient 3-in-1 mulching and bagging, and it also provides EDGEMAX which is a system that offers up-to-the-edge cutting.

Variable speed electric motor

The Black Decker CM2040 includes a variable speed electric motor that changes speeds as we already described. The battery can also be used with other Black and Decker cordless lawn and garden tools.

First impression

After I got tired of gasoline mowers with all kinds of gummed up carburetors, I decided to finally but the Black Decker CM2040 because I had my eyes on it for a long time. I can tell you that the mower has no trouble handling my backyard lawn and this is relatively new, and it grew about three inches. It was also able to flawlessly handle by front lawn as well which is moderately thick, and it’s about two inches high. It manages to mow the lawn in just a single pass but if you want to use it in places with thicker grass it struggles a bit, and you’ll need more passes over the grass to get the job properly done. This model of lawn mower is also much quieter compared to other models that I have tried so far. The fact that it comes with a lightweight frame makes it quite easy to maneuver and carry around. The only problem is that the batteries only last for about a half an hours and then you need two hours to fully recharge them. I kept thinking and searching for solutions regarding the battery life and I realized that the battery gets really hot while it’s powering the mower. When it’s depleted, it first has to cool down before you’re able to recharge it. I kept trying more methods to speed up this process, and I have to confess that I even ended up wrapping the battery and putting it in the freezer for 40 minutes. This speeded up the cooling process, but you can also put the battery somewhere in the shade to let it cool down because this will also work. Since the two 2.5 amp batteries and the 2.0 amp one are interchangeable, I decided to begin by using a 2.5 battery with the trimmer and trim the grass first. The trimmer will not heat the battery as much as the mower does. After I finish cutting and edging the front and the backyards, I put the battery back on the charger, and I let it charge. After that, I’ll just grab the remaining 2.5 amp battery and put it in the mower and use the 2.0 one when it dies, and I can tell you that this works great. Even if the mower is not as powerful as a gas mower, I can tell you that it provides enough power to cut even thicker grass. I also liked that because it’s lightweight it will not leave any deep wheel tracks on your lawn like heavier models usually do. The final result was always a lawn with a nice and smooth finish. I would recommend the Black Decker CM2040 to anyone who has a smaller yard with a medium thick grass.


What to like:

  • In the center of the mower, there is the battery compartment shielded by a robust black cover.
  • The handle has four quiet release levers that allow users to fold it down to save space when it’s in storage.
  • The machine comes with a removable safety key.
  • It also comes with a push-button starter and a bail handle that will shut down the motor when it’s released.
  • You just have to press the button and pull back the bail handle when you want to start the mower.
  • The Black Decker CM2040 is quieter compared to other models of lawn-mowers that you can find on the market.
  • Its lightweight frame makes it quite easy to maneuver.
  • The height adjustment allows you to choose one of six settings that range from 1.5 to 4 inches.
  • There is also a side discharge chute for use with an included mulching attachment.
  • The included rear chute uses a 15-gallon clippings bag.


What to consider

  • The Black Decker CM2040 uses a 40-Volt Lithium battery that provides you around 30 minutes of cutting time, and it takes a few hours to regain a full charge. But, on the other hand, it comes with two batteries and the machine is much lighter than a typical gas-powered mower.


Black & Decker Inc. warrants this product for two years against any defects in materials and workmanship. The defective product will be replaced or repaired.

Final verdict

If you love electric lawn mowers especially models that don’t include a cord, the Black Decker CM2040 is one of your best choices. It’s lightweight, quiet and it’s also powerful enough to handle any kind of small lawn with a medium thick grass. The fact that it comes with two batteries is also excellent, and overall, the machine is effortless to maneuver, and it will successfully manage to do its job in your backyard.

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