Cordless lawn mowers have come a long way in the last few years, with increased power, lighter weight and longer run time.

One of the newer models is the SunJoe Cordless Lawn Mower (16LM), with a 16” deck, 40V Li-ion battery and 40 minute run time.

I put it to the test on a ¾ acre lawn with a mix of fine fescue and St. Augustine grasses. Here’s what I found …

SunJoe Cordless Lawn Mower (16LM) Features

• Best uses: small to medium size lawns
• Deck width: 16”
• Cutting width: 15”
• Cutting height: 1.18” – 3.15” (6–position manual height adjustment)
• Grass bag capacity: 9.26 gallon
• Motor/rotor: 600 W brushless /15 inch steel cutting blade
• Weight (battery installed): 34.2 lbs.
• Battery: 40 Volt 4Ah (supplied as the standard battery with the mower)
• Battery charge time: approx. 1.5 hrs – 2 hrs.
• Battery runtime: approx. 40 minutes on a 40V 4Ah Li-ion battery

Assembly

The mower arrived neatly packaged, undamaged and completely assembled except for the handles.

The lower handle had to be installed and then set to the desired height (there are three height options) by tightening the multi-position height adjustment quick lock wheels (one on either side of the mower deck).

The upper handle had to be attached to the lower handle using a set of two upper handle knobs and bolts.

The upper handle can be folded over the lower handle by unscrewing the upper handle knob and bolts just enough to let the upper handle pivot over the lower handle. This feature makes it easy to rotate the upper handle forward (toward the mower) for easy transportation and stowing the mower in tight spaces.

The mower arrives neatly packaged with very little assembly required.

Easy To Use

The SunJoe cordless mower has some features that I really liked and that made it easy to use.

There’s a sturdy lifting handle in the center of the mower, making it easy to pick up the entire mower. This is a definite plus when transporting it, putting it into a storage area or for extra maneuverability when mowing.

There’s a nice big lift handle in the middle of the mower and the 6-position height adjustment lever is easy to use.

The cutting height can be easily adjusted by using the 6-position cutting height adjustment lever. It’s well placed on the side of the mower and moves the cutting height from a low of 1.18 inches to a high of 3.15 inches (according to SunJoe).

I found it easier to adjust the height upwards if I also lifted up on the nearest handle as I moved the height adjustment lever. While it’s tempting to grasp and lift up on the mower deck (rather than the handle), don’t do it! Never put your fingers anywhere near the cutting blades.

And the multi-position quick-lock wheels located on the mower deck make it easy to adjust the handle level for pretty much any sized operator.

The multi-position quick-lock wheels make it easy to adjust the handle height.

The mower is easy to start by depressing the safety lock button and pulling the switch bar (bail) until it touches the foam covered handle. The safety lock is hard to miss – it’s the big green button on the side of the right handle.

Upper and lower bars are made from steel and not plastic and the handle is covered in comfortable foam.

Battery Compartment

The easy to see battery compartment in the center of the mower has a clear plastic cover that’s lifted up 90 degrees to access the 40V 4Ah battery.

The battery compartment is spring-activated, which makes it easy to install and remove the battery. To install, simply push the battery all the way into the compartment until the battery’s push lock clicks, locking the battery in place. To remove the battery, push the battery down into the battery compartment (you’ll feel the spring pressure) and press the push lock on the battery until the battery is pushed back up beyond the locking position.

Two nice safety features are the locking button that keeps the battery cover firmly in place over the battery compartment, and the safety key that needs to be inserted after the battery is installed (the mower won’t operate without it). The safety key can be inserted in either direction.

Two nice safety features are the locking button and safety key.

One feature I would’ve liked to see on the SunJoe mower is the ability to check the battery level without having to open the compartment cover to press the indicator button on the battery.

Battery Charging & Run Time

The mower comes with a 40 Volt, 4Ah (Amp hour) lithium-ion battery, as well as a charger. Additional batteries are available on Amazon for $89.99 each (it’s always good to have a spare battery).

It takes 1.5 to 2 hours to charge the battery (using the charger that comes with the mower) after it’s been fully discharged.

>> See our FAQs About Li-Ion Batteries

It takes 1.5 to 2 hours to charge the battery

Average run time was about 40 minutes, depending on grass height, coarseness, and dryness. That was plenty of time to mow an entire ¾ acre lawn without running out of juice.

Some reports indicate that the battery can overheat when operated in high outside temperatures, causing the mower to stop altogether until the battery temperature falls within its operating temperature range. According to SunJoe’s operating manual, this is a safety feature – when the battery overheats (such as when the outside temperature is above 104F), an integrated protective cutoff will switch off the mower. I used it in 95F+ temperatures without any issue. I can’t image mowing a lawn in 104F+ temperatures!

I also noticed some discrepancies in the operating manual regarding battery storage temperatures. In one case, the manual states that the safe temperature range is from -4 degrees F to 113 degrees F.  Another section says not to charge the battery in a place where the ambient temperature exceeds 104 degrees F. Either way, you get the message – don’t charge or store the battery in a location that’s going to hit triple digits in summer, such as a garage or storage shed.

About The Motor

The SunJoe Cordless Lawn Mower model 16LM runs on a brushless motor, which offers some advantages over a more typical brushed motor, such as higher efficiency, increased reliability, reduced noise and a longer lifetime.

Brushless motors also tend to have a higher torque to weight ratio, meaning you get great performance in a lighter mower.

Good Mowing Performance

The SunJoe cordless mower makes a nice clean cut on both fine and coarse grass lawns. I tested it at various heights and even on wet grass, all with very good results.

The grass catcher bag has mesh sides and a hard bottom, making it both sturdy and collapsible for easy storage. Using the grass bag left the lawn virtually free of grass clippings.

The grass bag indicator window (a flap located on top of the grass bag) lets you easily see when the bag is full – the flap lies flat when the bag needs to be emptied. However, it’s a little flimsy so I’m not sure how long it’ll stay attached to the mower.

The grass bag indicator window lets you easily see when the bag is full.

No Mulching Capability

The SunJoe cordless mower is NOT a mulching mower. When the grass bag is disconnected from the mower, the ejector flap swings down against the mower’s rear housing but it doesn’t sit flush, leaving a huge gap through which the grass clippings shoot out. The end result is a clearly visible trail of grass clippings left on the lawn as you mow and a large wad of grass left inside the mower.

The SunJoe cordless mower is NOT a mulching mower – there’s a large gap between the ejector flap and mower body so grass clippings shoot out while mowing.

To be fair, SunJoe doesn’t advertise the 16LM as a mulching mower. However, the design makes it look like it will mulch – it has a rear hatch (ejector flap) that closes when you take the grass bag off. Other cordless mowers we’ve tested all have an ejector-type, spring-loaded flap that closes off the rear end of the mower and converts it from a grass catcher to a mulcher. I thought this was the case until I tried it …

When you lift the ejector flap, you’ll have a huge wad of grass clippings trapped inside the mower.

Some Improvements Needed

We had some real problems trying to attach the grass catcher to the mower. The plastic pieces on the mower and grass catcher didn’t align well and it took a lot of sliding, lifting, and repositioning the grass catcher for the ejector flap to lock into place.

The front wheels weren’t aligned perfectly straight. While it looked odd and caused me to question SunJoe’s quality control, it wasn’t a major problem, as the mower was easy to push and it cut straight lines even with the wonky wheels.

I’m not sure if the cable that attaches to the safety lock button and switch bar (bail) will stretch over time (we’ve seen this happen on other mowers). It worked fine for our testing.

The SunJoe mower could definitely use a larger grass bag. The one supplied is rather small (only 9.26 gallon capacity) and had to be emptied more frequently than some other mowers we tested. And because it’s not a mulching mower, you have no option but to use the grass catcher.

Given the battery run time, you could conceivably mow a large (acre+) lawn with this mower but you’d spend most of your time emptying the grass bag! This feature alone leads me to only recommend the SunJoe mower if you have a small yard to mow.

Safety First

The SunJoe mower is relatively quiet (under 100 dB) but I still recommend using hearing protection, as well as the usual protective gear when using powered lawn tools (safety glasses, long pants, sturdy shoes, gloves).

This is an electrical device and should not be used in wet weather or severely wet lawn conditions as you risk getting a nasty electrical shock.

Warranty

The SunJoe cordless mower has a 2-year warranty against defects in material or workmanship when used for normal residential purposes. If you’re using it for any business, commercial or industrial use, then the warranty is limited to only 90 days from the original date of purchase.

The batteries are covered in full for 90-days from the date of purchase.

Recommendation

As non-mulching movers go, I liked the unit. It was lightweight, easy to handle, had a decent run time, was extremely maneuverable, and made a nice clean cut. I thought the adjustable height handles were a real plus, along with both the grass indicator window and springs within the battery compartment that made for an especially easy removal of the battery. It was compact, fairly easy to fold the upper handle onto the lower handle for easy storage, and was quiet.

The thing that bothered me most was the need to jiggle and force the ejector flap into place on the top of the grass bag. Hanging the grass bag on the back of the mower was finicky as well. Since the grass bag must be installed to use the mower, and it fills up quickly so needs to be frequently emptied and replaced, this quickly became a real annoyance. Some engineering tweaks to the plastic molding and perhaps some additional quality control could easily resolve this issue.

Where to Buy

The Sun Joe 40-Volt 16-Inch Cordless Mower, Model iON16LM is available from the manufacturer for $379.99. It is also sold at a variety of big box stores, including Walmart, Sears, Home Depot, Target, Bed Bath and Beyond, Kmart, etc.

If you’re looking for free shipping and a three-day delivery, your best bet is Amazon Prime.

Sun Joe iON16LM 40-Volt 16-Inch Brushless Cordless Lawn Mower, Kit (w/4.0-Ah Battery + Quick…

A good option for smaller yards

$299.99

See it on Amazon