Pros / It can run for 45 to 60 minutes, which is enough to mow up to a 1/3-acre lawn.

Cons / This mower isn’t self-propelling.

 Verdict / The Black & Decker CM2040 performs as reliably as a gas-powered mower and is easy to use.

Whether you enjoy mowing your lawn or dread even the thought, you may be hesitant to purchase a gas mower that produces fumes and requires maintenance. Luckily, electric lawn mowers have improved over the years. If you still aren’t sure about switching to an electric model because you've heard they are limited compared to gas-powered ones, the Black & Decker CM2040 may convert you.

This 20-inch, 40-volt cordless electric mower can bag, discharge or mulch grass clippings – and it does so better than many of its top competitors. On top of its great features, this mower is easy to use.

It may be true that gas mowers have higher horsepower and can cut extremely thick and wet grass, but the reality is that very few lawns require a motor with that much power. The Black & Decker CM2040 effectively cuts lawns that are well-maintained at acceptable lengths and kept in good condition. If you mow your lawn as recommended – when it is dry and no more than 8 inches tall, depending on grass type – this electric mower can make the same clean cuts in a single pass as the best models available.

This electric lawn mower is well-designed, cutting a wide 20-inch swath with each pass. The deck is made from a durable polymer material that can stand up to years of mowing even the most rugged terrains. The CM2040 comes with two 40-volt li-ion batteries. The batteries weigh under 2 pounds each, so the mower’s overall weight is less than 45 pounds. Each battery charges in about two hours.

One 40-volt battery provides roughly 45 to 60 minutes of runtime, though the exact time varies depending on grass thickness and cutting height. No matter which setting you use, the battery provides enough power to handle a yard measuring 1/3-acre or less. Unfortunately, this mower does not have self-propulsion, which means you have to push it with your own strength the whole time.

The CM2040’s mower deck has a three-in-one switch that makes it easy to select from its modes: bagging, mulching or discharging your grass clippings. When the mower is in bagging mode, you simply need to make sure the bag is attached and you are good to go. To switch between bagging, mulching and discharging, you just flip the switch. Because the bag is a bit small and clippings sometimes find their way out, the CM2040 didn't score as well as comparable mowers in our bagging tests. However, it does mulch and discharge its clippings efficiently.

Another one of this Black & Decker’s great features is its wheel height adjustment. With many mowers, you select the cutting height by raising or lowering each wheel individually, but you set the CM2040’s with a one-touch adjustment system. This easy-to-use system uses a single handle on the right side of the mower that you can comfortably grip and squeeze with one hand. Because the mower's height adjustment system is pressurized, this requires very little effort – you simply put your own weight on the mechanism to adjust the blade and release the handle to lock the mower at the desired cutting height, between 1.5 and 4 inches.

One of the Black & Decker CM2040’s most important features is its safety key, which is located next to the start button. You can pull the key out to cut the motor to avoid an accident, and it has to be reinserted for the mower to start again. This also means you can safely store it with the battery installed without worrying about a child accidentally starting it.

Black & Decker provides a three-year warranty that protects against defects in material or workmanship and includes two options for free part repair or replacement. The first option is to return the defective mower to the retailer you purchased it from; the second option is to take or send your mower to a Black & Decker owned or authorized service center.

All of these features and benefits are good, but they weren't enough to make it our top pick – the EGO LM2102SP.

You can also find support by email and product FAQs, and phone support is available during normal business hours. The company's website thoroughly describes its products, services and warranties. Beyond the basic features on its website, you can also access online communities full of fellow Black & Decker consumers by becoming a member of My Black & Decker. This online community also grants you access to eNewsletters and new product notifications.

Black & Decker CM2040 Visit Site
  • Volts
  • Total Weight
  • Battery Charge-time
  • Battery Weight
  • Cutting Path Width
  • Warranty
  1. Higher voltage means stronger torque and a smoother cut.
    Higher is Better.
  2. 3  Black & Decker
    40.0 Volts
  3. 1  EGO
    56.0 Volts
  4. 2  Kobalt
    80.0 Volts
  5. Category Average
    49.78 Volts


The Black & Decker CM2040 is worth considering as you shop for a new electric lawn mower. Even though it does not have an innovative self-propel function, this mower cuts grass as well as most of the gas mowers currently on the market. Add in all of the CM2040's features that make mowing your lawn convenient – three bagging modes, low noise level, low maintenance, etc. – and you have one of the best electric lawn mowers available.

Black & Decker CM2040 Visit Site

Specifications and Benchmarks


Average Battery Run-time (minutes)
Battery Charge Time (hours)
Battery Type
Batteries Included
Battery Weight (pounds)
Removable Battery
Battery Remaining Indicator


Optimal Yard Size
1/3 acre
Cutting Path Width (inches)
Number of Cutting Positions
Minimum Cut Height (inches)
Maximum Cut Height (inches)


Safe-Start Mechanism
Single-Lever Height Adjustment
Handle Cushioning
Mulch Option

Mower Design

Total Weight (pounds)
Deck Material
Front Wheel Diameter (inches)
Rear Wheel Diameter (inches)
Side Discharge

Warranty & Support

3 Years
Phone Support
Email Support
Operator's Manual Online
Service Center Locator