The Black & Decker CM2040 is a 20-inch cordless lawn mower. It comes with two 40-volt Lithium batteries. While one battery is in use you can store the other in a compartment on top of the mower for quick and convenient access. Change the cutting height to 7 different settings, ranging from 1 ½” to 4”. Choose between bagging, mulching or discharge the grass clippings to the side.
- 20” cutting swath.
- 40V Max Lithium batteries.
- Easy cutting height adjustment.
- EdgeMax, allows cutting close to obstacles.
- 3-in-1 function.
- 2 year limited warranty.
Black & Decker CM2040 review
The Black & Decker CM2040 is a cordless lawn mower, which is powered by 40-volt Lithium batteries. B&D has, of course, gone for a color scheme of orange and black, which I think look good.
The mower is mainly made of plastic, which makes it lightweight. Since the mower only weighs about 55lbs (25kgs) it is easy to push and maneuver. The wheels are generously sized and wide, which prevents the wheels from digging in and leaving tracks on your lawn.
My first impression of the mower is that it is of high quality and durable. The 20-inch deck is made of thick plastic that seems to be able to handle some beating. The CM2040 is off to a good start!
- Lawn mower, CM2040.
- 2.5Ah 40 voltage Max Lithium Batteries (2).
- Grass bag.
- Battery charger.
The mower comes almost fully assembled, which most lawn mowers do these days. You will be able to get this mower fully assembled in less than 5 minutes and that’s without any tools as well. Extend the handle and insert the two bolts that comes in the box before locking them tight. That’s it!
The handle can easily be collapsed over the mower again so you can more easily transport or store the mower. With the handle folded over the mower, the space needed to store the mower is minimal. You can even hang it up on the wall.
The Black & Decker CM2040 comes with two 40-volt Lithium batteries, each with 2.5 Ampere hours (Ah). However, the mower uses only one battery at the time. You can have the second battery stored in a compartment on top of the mower. I really like this feature and found it very convenient.
When the first battery is completely drained, just switch the batteries and you are good to go again. No need to go and fetch the second battery from the house or garage. While you are using the second battery the first one will have time to cool down before you recharge it. Yes, the battery needs to cool down properly before it will take any charge. If you plug a battery that has just been used to the charger it will just sit there for about 30 minutes, if not more, before it starts to recharge. Recharging each battery takes about 60 minutes if they are cooled down or not been used recently.
I found that the amount of mowing you can get done with the batteries are highly dependent on the condition of the lawn. Of course, this is normal, but I have never experienced such big fluctuations in cutting time. If the lawn is dry and nicely manicured, and you only want to trim off an inch you will get up to 30 minutes of mowing for battery. However, a lush lawn that hasn’t been mowed for over a week you might get as little as 10 minutes out of each battery. Black & Decker should definitely have gone for some batteries with more Ampere hours (Ah).
The Black & Decker CM2040 really struggles with “tougher” conditions and disappoint with the cutting time. This could have been forgiven if the charger had managed to fully recharge a battery while the second is being used. If you own other B&D tools using the same type of 40-volt batteries, these can be used with the mower. This will let you get more time to mow and improve you overall usage of the mower.
How does it mow?
As I just mentioned above, the B&D CM2040 struggles with tall grass and is best suited for a nicely manicured small lawn that is cut regularly.
The mower has something Black & Decker calls AutoSense technology, which is supposed to change the speed and power of the motor to adjust to the conditions. I don’t know if this function works or not, can’t say there is any noticeable changes in the power output. Could be it struggles with the easier parts as well and is therefore stuck in max power!
The mower can stall and overheat if the conditions are too tough. These conditions aren’t unreasonable tough for a 40-volt cordless mower, only thick and tall grass. If the mower overheats it shuts down and it won’t let you restart it before it cools down. This is of course annoying and you need to take an involuntary break. It is a shame that the motor and batteries let this otherwise great mower down.
Let us look at some of the positive things this mower can offer. The ergonomics are really good and the mower is easy to maneuver. Cutting in straight line is a breeze, the light weight of the mower and large wheels makes it almost effortless to push. The mower rides well over any uneven parts of the lawn. Even maneuvering around obstacles is simple.
I like that the deck is the widest part of the mower which let you cut really close to the edge of fences and other obstacles. The mower will only leave a thin strip of grass along the edge. B&D calls this EdgeMax and is a feature I really appreciate.
You can either mulch, bag or discharge the clippings to the side with this B&D CM2040 mower.
The grass catcher bag is made of see-through nylon, which let you check how full it is with a quick glance. Attaching and taking the bag off is very easy and works well. The bag can hold up to 1.6 bushels (15 gallons/ 56 liters).
The side chute works well. The mower throws the grass clippings to the side without any issues. The side chute comes in the box and isn’t difficult to attach. If you need guidance the manual has a good description how to do it with good graphics.
I am really pleased with the mulching mode. The grass clippings are chopped up into fine pieces that is scattered evenly across the lawn. The results were outstanding.
The cutting height can be set to 6 different heights, ranging from 1 ½” to 4”. The height is adjusted with a single lever on the side of the mower and is both fast and easy. This is good because you will need to use it a lot if the grass has grown tall. Since the mower struggles and is prone to overheating, tall grass is best managed by only cutting off a bit at the time for every pass.
I have compared the Black & Decker CM2040 against other similar sized cordless mowers to give you an idea of other viable options.
Black & Decker has also a model name CM2045, which is the exact same model, but in completely black. It looks really cool, but unfortunately B&D sells this model with two 2.0Ah batteries instead. So you get a really cool looking mower with even less endurance. This would have been interesting if B&D had increased the cutting time instead of reducing it.
The first option you might want to consider is the Black & Decker CM1936ZA (read my full review here). This is an older model with a 36-volt lead acid battery. The lead acid battery weighs significantly more, but will let you mow up to 1/3 acre with one charge. However, the recharge time is 12 hours! The CM1936 can handle tougher conditions and will stall a lot less. There is also a model with Lithium-ion batteries instead, which might be more interesting. It is called B&D CM1936ZA.
The next mower is the Greenworks 25302 Twin Force G-Max (read my review here), which is an intriguing cordless mower. What is special with this mower is that it has two cutting blades underneath the 20-inch deck. The mower comes with two Lithium-ion batteries, one 2Ah and one 4Ah. The 4Ah battery will let you mow for up to 70 minutes, which is much more than the CM2040. It is usually a bit pricier than the CM2040, but in my opinion a much better cordless mower. Absolutely worth a closer look!
The last cordless mower I have compared the B&D CM2040 to is the Greenworks 2500502 DigiPro G-Max. It also comes with a 4Ah and a 2Ah Lithium-ion battery as the previous Greenworks mower. This mower is more traditional and has one blade that is driven by a brushless motor. The 4Ah battery will let you mow for up to 60 minutes, and if that’s not enough you will have a 2Ah battery that will let you mow for another 30 minutes. The Greenworks 2500502 is usually priced similarly as the B&D CM2040, which makes it a really good contender.
To summarize, I would prefer and recommend either of the Greenworks mowers over the Black & Decker CM2040. In my opinion, they both have more power and same building quality, if not better.
|Black & Decker CM2040||Black & Decker CM1936||Greenworks 25302||Greenworks 2500502|
|Cutting deck||20” / Plastic||19” / Plastic||20” / Plastic||19” / Steel|
|Battery type||Lithium||Lead acid||Lithium-ion||Lithium-ion|
|Voltage/ Ah||40V / 2.5Ah (x2)||36V / 10Ah||40V / 2Ah & 4Ah||40V / 2Ah & 4Ah|
|Endurance||Up to 30 minutes for each battery||1/3 acre
Up to 45 min
|1/3 to ½ acre
Up to 70 min
Up to 60 min
|Recharge time||About 1 hour per battery||12 hours||2 hours (4 Ah)
1 hour (2 Ah)
|2 hours (4 Ah)
1 hour (2 Ah)
|Cutting height||1 ½” to 4”
30mm – 100mm
|1 ½” to 3 ½”
30mm – 89mm
|1 3/8” to 3 3/8”
35mm – 86mm
|1 ¼” to 3 ½”
32mm – 89mm
|Types of discharge||Bagging (1.6 bushels)
|Bagging (1.7 bushels)
|Bagging (2.2 bushels)
|Weight||55lbs. / 25kgs||72lbs. / 33kgs||42,5lbs. / 19kgs
|46lbs. / 21kgs|
Black & Decker has priced their CM2040 about the same as their competitors, but their batteries are under par.
- Lightweight, but durable.
- Storage for 2nd battery.
- Too little cutting power.
- Poor endurance.