Quick verdict
A 20-inch brushless self-propelled mower that ships with two 40V 4.0 Ah packs and a charger, so one pack cuts while the other charges. It suits a flat to moderately sloped lawn of about a quarter acre where a push mower has become a chore. The caveat is that PowerSmart does not publish a runtime figure or a weight, so plan around owner reports rather than a spec sheet.
Strengths
- Two 40V 4.0 Ah packs and a charger in the box
- Rear-wheel self-propelled drive engaged with one lever
- Brushless motor with 3-in-1 mulch, bag and side discharge
- Six height positions from 1.5 to 3.9 inches on a single lever
- 20-inch deck covers more per pass than the common 16 and 17-inch kits
Weaknesses
- No runtime or coverage figure published by the maker
- Drive speed appears fixed; the listing does not mention variable speed
- Deck material and weight are not stated
- Packs lock you into the PowerSmart 40V platform
The overall YardToolLab Score is out of 100. Section scores are out of 10.
Who this mower is for
A quarter-acre lawn with a slope by the driveway is the point where a 16-inch push mower stops being pleasant. The PowerSmart MB2420SA is built for that lawn: a 20-inch deck so there are fewer passes, a rear-wheel self-propelled drive so the slope does not fall on your shoulders, and two 40V 4.0 Ah packs so the cut is finished without waiting on a charger. It is a budget kit from a brand that sells mostly through Amazon and big-box stores, and it is specified accordingly.
This review is based on the maker’s published specifications and on recurring owner feedback. We have not run this product ourselves.
What you get
The box holds the mower, two 40V 4.0 Ah lithium packs and a charger. The motor is brushless, the deck is 20 inches wide and the cutting height moves through six positions from 1.5 to 3.9 inches on a single lever. The deck is 3-in-1: mulch, rear bag or side discharge. What the listing does not say matters too. There is no runtime figure, no acreage rating, no bag capacity and no weight. PowerSmart also does not state the deck material; at this level it is most likely steel, but check the product page before you assume.
Cutting and power
A 40V brushless motor on a 20-inch blade sits in the middle of the cordless walk-behind class, below the 56V, 60V and 80V machines and above the 20-inch kits that still use brushed motors. PowerSmart says the brushless motor runs cooler and quieter with less vibration, which is true of brushless designs generally. Owners of PowerSmart 40V mowers describe a clean cut in weekly growth and a noticeable slowdown in thick spring grass, where the usual fix is to raise the deck a notch and overlap passes. Side discharge is the mode to use when the grass has gotten away from you, since mulching long damp clippings under a 40V deck tends to clump.
Runtime and batteries
Two 4.0 Ah packs at 40V carry about 320 watt-hours between them. PowerSmart does not translate that into minutes or acres, so a rough rule of thumb is a quarter acre of normal weekly growth across both packs, less with the self-propel running the whole time. The second pack charges while the first is in use, so swap and keep going. The packs fit PowerSmart’s other 40V tools, which is useful if you plan to add a trimmer or blower from the same line, and a limitation if you already own another brand’s batteries.
Build, handling and ergonomics
The self-propel is engaged by pulling a lever, and the rear wheels pull the mower forward. The listing does not mention a speed adjustment, so treat it as a single fixed pace. Rear-wheel drive is the right choice for slopes and for a full bag, since the weight sits over the driven wheels. Weight is not published; a 20-inch self-propelled battery mower with two packs typically lands somewhere in the 50 to 60 pound range, which is a one-person lift onto a tailgate only if you are used to it. A recurring note from owners of PowerSmart mowers is that the handle hardware benefits from a check and a snug after the first few cuts.
Living with it
There is no oil, no spark plug and no fuel to stabilize. Keep the blade sharp, because a dull blade costs runtime on a battery mower as well as cut quality. Scrape the underside after wet cuts. Store the packs indoors over winter at about half charge rather than leaving them on the charger in a cold garage. The listing does not state the warranty term, so read the product page and keep the receipt; PowerSmart typically backs its tools for a fixed period and its packs for a shorter one.
Alternatives to Consider
The Greenworks 40V 21-inch self-propelled kit with two 4.0 Ah packs is the closest match in a bigger brand with a wider accessory range. The Ryobi 40V HP 20-inch self-propelled mower adds variable speed and a Home Depot service counter. If your lawn is flat and under a fifth of an acre, a PowerSmart or Greenworks 40V push mower is lighter, cheaper and simpler.
Verdict
Buy the PowerSmart MB2420SA if you want a self-propelled 20-inch cordless mower with two packs in the box for a quarter-acre lawn and you are comfortable with a value brand. Skip it if you need a published runtime, variable drive speed or a battery platform that spans a big catalog of other tools.
Full specifications
PowerSmart 20-Inch Self-Propelled Cordless Lawn Mower MB2420SA with Two 40V 4.0 Ah Batteries and Charger FAQs
The listing describes a single lever that engages the rear-wheel drive and does not mention a speed control, so assume one fixed pace. Owners of fixed-speed mowers generally find the pace a comfortable walk; if you want to crawl on slopes or hurry on open stretches, look for a variable-speed model.
PowerSmart does not publish a runtime for this model. Two 40V 4.0 Ah packs hold about 320 watt-hours between them, which on a 20-inch brushless mower is typically enough for a quarter-acre lawn in normal weekly growth, with less in tall or wet grass.
No. The listing says one pack powers the mower while the other charges, so you swap packs mid-cut rather than drawing on both together.
The listing describes mulching, rear bagging and side discharge as the three modes, which implies the bag and plug are included. Bag capacity is not stated, so expect to empty it often on a long lawn.
