HART 40V 21″ Supercharge Self-Propelled Lawn Mower Review

HART 40V 21-Inch Self-Propelled Lawn Mower

Whip Your Lawn Into Shape With the HART 21-inch Self-Propelled Lawn Mower

What a difference a year makes! Looking back on HART’s 40V cordless mowers, there was plenty of room to move into higher performance levels. The HART 21-inch Supercharge self-propelled lawn mower promises to reach higher as we move into the spring mowing season. We tested it to see if it’s a good fit for your lawn.


  • Excellent cut quality
  • Easy handle folding for vertical storage
  • Bag, mulch, or side discharge
  • Single-point height adjustment
  • Power boost mode gives you a brief jump in power in thick grass


  • We’d like the presence bar recessed into the handle to make the grip more comfortable
  • Drive speed slider is easy to bump by mistake

Editor’s Note: Check out our article on the best electric lawnmower to get our top picks in all categories.

Using the HART 21″ Supercharge Self-Propelled Lawn Mower

Cutting Power

HART’s brushless motor spins a 21-inch blade that has some decent muscle behind it. Cutting through our thick St. Augustine grass, the Supercharge 21-inch self-propelled mower was much more confident than some of the previous HART mowers we’ve tested.

One cool feature is a temporary power boost. The motor adjusts power automatically as we expect. You can also proactively kick it up when you’re approaching a tough patch by just pressing the blade activation button again. It steps up into high power for about 6 seconds.

HART 40V 21-Inch Self-Propelled Lawn Mower Controls

There’s a power gap to the top-performing battery-powered mowers, but they’re also hundreds of dollars more. In terms of replacing gas, this mower cuts better than the 140cc class.

Cut Quality

The HART Supercharge lawn mower gives you three discharge options and includes everything you need with the mower. Using a true side discharge rather than a rear attachment, the mower easily distributed cuttings several feet out of our mowing path.

If you’re like us and prefer to mulch, the plug is simple to install. Just lift the rear hatch and seat the plug to close off the bagger chute. The mulching results were satisfyingly good compared to what we’ve seen from HART in the past and much more like what we expect from mid to high-level mowers.

HART 40V 21-Inch Self-Propelled Lawn Mower

The high airflow that contributes to very its mulching characteristics also produces impressive bagging for a battery-powered mower.

Cut Evenness

Looking back over the section of grass we cut, we were definitely pleased with the results. Save for a few stray blades, we saw big improvements to how even the overall cut was.


The HART 21-inch Supercharge self-propelled lawn mower has two active battery bays. It doesn’t have an automatic switchover, though. When one battery runs out, you need to flip the red key under the lid, restart the mower, and keep on truckin’. If you have a smaller lawn, you’re able to run the mower on just one battery.

HART Battery Bay

HART estimates you can cut up to 3/4 of an acre on one charge in optimal conditions. We tested runtime with a medium maintenance cut on a dry day with temps hovering right around 90° F (runtime tends to drop slightly at higher temps). With the two 6.0Ah batteries that come in the kit, we cut for a total of 50:57. Hart’s estimation may be a little ambitious, but a 1/2-acre is certainly possible.

HART Supercharge Self-Propelled Lawn Mower Design Notes

  • The 21-inch Polymax composite deck is lightweight, corrosion-resistant, and strong enough to withstand moderate impacts from yard debris
  • The Fast-Fold handles make it easy to store this mower upright if space is limited
  • Quickly adjust the deck height between 1 inch and 4 inches with a single-point adjustment
  • LEDs in front for mowing in low light situations
  • A sliding thumb switch lets you easily adjust the drive speed to match the walking pace you prefer

HART 21-inch Supercharge Self-Propelled Lawn Mower Price

Grab this HART mower at Walmart for $498. It comes with two 6.0Ah batteries and a rapid charger that’ll charge each battery in one hour. It has a 5-year limited tool warranty as well as a 3-year limited battery warranty.

The Bottom Line

After using the HART 21-inch Supercharge self-propelled lawn mower we’re impressed with the improvements in performance, cutting performance, and design compared to last year’s models. The design team over at HART set their sights high and stepped up to compete against other mowers in the $600 range.

HART 21-inch Supercharge Self-Propelled Lawn Mower Specifications

  • Model: HART HLPM061US
  • Power Source: HART 40V battery
  • Cutting Swath: 21-inch
  • Accessories: mulch plug, side discharge chute, collection bag
  • Motor: Brushless
  • Self-propelled
  • Cutting Height: 1-4 in.
  • Deck Height Adjustment: 7-positon single-point
  • Warranty: 5-year tool, 3-year battery
  • Price: $498 (kit)

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