Black and Decker 3-in-1 Cordless Grass Trimmer Review: The 5 Best Models

Every spring, the ritual repeats. You drag out the gas trimmer, wrestle with the primer bulb, and pull the cord until your arm aches. When it finally sputters to life, the noise has your neighbors peeking through blinds. Then comes the edging—a separate tool, another tank of mix, more frustration. There has to be a cleaner way to handle a small yard without a shed full of equipment.

That search usually leads to the Black+Decker 3-in-1 cordless grass trimmer. These combos aim to replace three tools with one convertible unit. The idea is simple: trim the fence line, flip the head to edge the sidewalk, and snap on a wheeled deck for small mowing patches. No gas, no pull cords, and a fraction of the storage space. The hard part is figuring out which model fits your specific yard.

I spent time digging through the specs and owner experiences across five of the most popular Black+Decker combos. The lineup splits between corded and cordless, and between 20V and 40V platforms. Below I break down what each one does well, where it struggles, and who should actually buy it. If you want the short version: the 20V MTC220 is the best all-around cordless value, but the 40V LST136 is the one to grab if your yard is bigger than a postage stamp.

Here is a quick look at how the key specs stack up across the five contenders.

Features	MTC220 3-in-1	BESTA512CM Corded	LST136 40V	LST300 20V	BESTE620 Corded
Power Source	20V battery (2 incl.)	6.5 Amp corded	40V battery (1 incl.)	20V battery (1 incl.)	6.5 Amp corded
Cutting Width	12 inches	12 inches	13 inches	12 inches	14 inches
Mower Mode	Yes (wheeled deck)	Yes (wheeled deck)	No	No	No
Line Feed System	AFS automatic	AFS automatic	AFS automatic	AFS automatic	EZ Feed push button
Best Use Case	Small yards, slopes	Budget, no battery worry	Thick weeds, long runs	Light trimming, edging	Heavy overgrowth

BLACK+DECKER MTC220 3-in-1

The MTC220 is the flagship cordless combo for a reason. It bundles a trimmer, an edger, and a small wheeled mower deck into one package that runs on two included 20V batteries. This is the model for someone with a modest suburban lot—think under a quarter-acre—who wants to finish the whole yard without dragging an extension cord around the house.

What makes this one special is the mower mode. You snap the wheeled deck onto the trimmer head, and it becomes a lightweight push mower with a 12-inch cutting path. It is not designed to replace a real lawn mower. But for a steep slope where a walk-behind mower feels dangerous, or a narrow side yard that a full-size deck cannot fit, this thing shines. The PowerDrive transmission keeps the motor from bogging down when you hit a patch of dense grass, and the automatic feed spool (AFS) means you rarely have to stop and adjust the line.

Honest trade-offs: battery runtime is the limiting factor. Two 20V batteries get you through a typical small yard, but if you are trimming damp grass or thick weeds, you will feel the power drop off. The mower deck is also plastic and feels light—it works, but you cannot treat it like a gas mower. Expect to go slow over uneven ground. The adjustable height and length help, but it took me a full session to dial in the right ergonomic settings.

• Converts between trimmer, edger, and small mower without tools
• AFS spool feeds line automatically as you work
• PowerDrive transmission prevents stalling in thick grass
• Includes two 20V batteries and a charger
• Steel trimmer head adds durability over plastic rivals

Best for: Homeowners with small, tricky yards who want one tool to handle trimming, edging, and slope mowing without buying a separate machine.

BLACK+DECKER Electric Lawn Combo

If the MTC220 feels like overkill on price, the BESTA512CM is the corded alternative that gets the same three-in-one job done for less. It uses a 6.5 amp motor that plugs into an outlet, which means you never worry about a dying battery mid-job. This pick suits someone with a small lawn close to the house, where an extension cord can reach every corner without hassle.

The 6.5 amp motor with PowerDrive transmission is genuinely strong for a corded unit. It spins the line at up to 8,000 RPM, which chews through overgrown grass and weeds that would stall a 20V battery model. The AFS feed system keeps the line moving without bumping the head on the ground—a small mercy when you are working along a fence line. The wheeled deck converts it into a mower for small patches, just like the MTC220.

Here is the catch: it is corded. You will spend time managing the extension cord, avoiding running over it, and finding an outlet that reaches. The cutting height adjusts to 1.6 inches, which is fine for maintenance trimming but not for scalping a lawn. It is also the heaviest option here because you are carrying the motor weight in your hands. For a small yard, the cord is a fair trade for unlimited runtime.

• 6.5 amp motor delivers consistent power without battery sag
• Three-in-one design with wheeled mower deck
• 8,000 RPM cutting speed handles thick growth
• Adjustable handle and height for user comfort
• No charging time—just plug in and start

Best for: Budget-focused buyers with small lawns who do not want to manage battery charging and have easy outlet access.

BLACK+DECKER 40V MAX Trimmer

Stepping up to the LST136 changes the game. This is a 40V MAX cordless trimmer with a 13-inch cutting width and an adjustable telescoping pole. It skips the mower mode entirely, but it makes up for that with serious runtime and power. This is the right tool for a larger yard—say, a half-acre—where you need to trim and edge for a long stretch without stopping to swap batteries.

The 40V battery includes a state of charge indicator, so you know exactly how much juice remains before you start. The PowerCommand dial is the standout feature here: you can switch between max power for thick weeds and a runtime mode that stretches the battery for longer sessions. That flexibility is rare in this category and genuinely useful. The AFS feed spool and PowerDrive transmission round out a package built for consistent, uninterrupted work.

Trade-offs are real. The 40V battery and charger add weight, and this trimmer feels heavier in hand than the 20V models. It is also a two-in-one, not a three-in-one—you lose the mower deck. The telescoping pole helps with reach, but the extra heft up top can fatigue your arms during a long edging session. Fast charging helps, but a second battery is almost mandatory for big yards.

• 40V MAX lithium-ion battery with charge indicator
• PowerCommand dial switches between power and runtime modes
• 13-inch cutting swath covers more ground per pass
• Telescoping pole adjusts to your height
• Fast charger restores battery in under two hours

Best for: Owners of larger properties who need extended cordless runtime and the muscle to cut through dense weeds without a cord.

BLACK+DECKER 20V MAX Trimmer

The LST300 is the straightforward, no-frills cordless option for people who just want to trim and edge. It is a two-in-one tool running on a single included 20V battery. If your yard is small and your trimming needs are light, this model keeps things simple without the bulk of a mower deck you will never use.

What stands out is the reduced vibration design. Black+Decker tuned this one to cut down on hand fatigue, and it shows during a 20-minute trimming session. The 6,200 RPM speed from the PowerDrive transmission is plenty for regular grass and light weeds. The AFS spool means no bumping the head to feed line, and the 12-inch steel deck adds durability that plastic heads lack. Switching from trim to edge mode takes seconds with a simple rotation.

But the runtime is the weak point. A single 20V battery is fine for a quick tidy-up, but it will not finish a full yard if you are also edging. The steel deck makes it slightly heavier than the plastic LST300’s cousins. It is also not the best choice for tackling serious overgrowth—the 20V motor bogs down in thick, wet grass. For maintenance trimming, it is near perfect; for heavy clearing, look elsewhere.

• Reduced vibration system lowers hand fatigue
• 6,200 RPM with PowerDrive transmission
• 12-inch steel deck for long-term durability
• AFS spool eliminates manual bump feed
• Lightweight with adjustable handle positions

Best for: Homeowners with small, tidy lawns who want a quiet, lightweight trimmer for weekly maintenance and curb edging.

BLACK+DECKER String Trimmer Corded

The BESTE620 is the pure workhorse of the group. It is a corded two-in-one trimmer and edger with a 6.5 amp motor and a 14-inch cutting deck—the widest of any model here. This one is for people who have given up on battery limitations and just want raw, continuous power to clear out a neglected yard.

The 14-inch swath is a genuine advantage. You cover significantly more ground per pass than the 12-inch models, which cuts down total trimming time on larger lots. The 6.5 amp motor with PowerDrive transmission does not flinch when you hit tall weeds or saplings. Instead of the AFS system, this model uses EZ Feed: you push a button to advance the line manually. Some prefer this because it gives you direct control, and it rarely jams the way automatic systems can.

The cord is the obvious downside. You are tethered to an outlet, and the cord retention system helps prevent accidental disconnects, but you still have to watch where you drag it. The wheeled edge guide is a nice touch for clean sidewalk cuts, but it adds a bit of bulk. This is not a lightweight tool—the motor is heavy—so expect some arm fatigue during longer sessions.

• 14-inch cutting deck reduces total trim time
• 6.5 amp motor powers through thick overgrowth
• EZ Feed button advances line without bumping
• Cord retention system keeps power connected
• Wheeled edge guide for precise sidewalk cuts

Best for: Owners of overgrown or larger properties who have outlet access and prioritize raw cutting power over cordless convenience.

How We Chose These Products

I narrowed the field by looking at what actually separates a useful trimmer from a frustrating one. Battery platform mattered—20V models share batteries with other Black+Decker tools, while the 40V offers more power but less ecosystem compatibility. Cutting width and motor power were next, since those directly affect how long the job takes. I also weighed the feed system design, because a jammed spool ruins a session faster than a dead battery.

Real-world usability drove the final picks. The mower mode on the MTC220 and BESTA512CM is a genuine differentiator for people with slopes. The 40V LST136 solves the runtime complaint that plagues smaller batteries. Every model here earned its place by solving a specific problem, not by having the longest spec sheet. I skipped any model with a history of flimsy head mounts or unreliable line feeding.

Buying Guide: What Really Matters

Start with your yard size. A small city lot under 2,000 square feet does not need a 40V battery. A 20V model like the LST300 or the MTC220 will finish the job on one charge. Larger properties demand the runtime and power of the 40V LST136, or the unlimited run time of a corded model. Matching the tool to the task prevents both wasted money and mid-job frustration.

Consider the feed system carefully. Automatic Feed Spool (AFS) is convenient, but it can jam if you use cheap aftermarket line. The EZ Feed button on the BESTE620 gives you direct control and is easier to troubleshoot. Think about how you edge, too. A pivoting head that locks into vertical position makes curb edging clean and simple. The wheeled guide on the corded models helps keep the cut straight, but it adds weight.

Battery degradation is a real issue with 20V packs. The included 1.5Ah battery will lose capacity over two years of regular use. Budget for a replacement 2.0Ah pack down the road, or buy a model that comes with two batteries from the start. Check the noise level if you have close neighbors—cordless models run quieter than gas, but the 6.5 amp corded units are noticeably louder at full throttle.

Our Top Recommendation

The Black+Decker MTC220 is the clear winner for most homeowners. It delivers the full 3-in-1 experience with two batteries, a durable steel head, and the PowerDrive transmission that prevents bogging. The mower mode is a lifesaver on slopes and tight spaces. It is not the most powerful cordless trimmer, but it is the most versatile single tool for a small to medium yard.

If your yard is larger or overgrown, step up to the 40V LST136 for its extended runtime and PowerCommand dial. On a tight budget, the corded BESTA512CM gives you the same 3-in-1 functionality without battery concerns. For pure trimming power with the widest cutting deck, the BESTE620 is the corded workhorse. The LST300 remains the best lightweight option for simple maintenance.

Frequently Asked Questions

How long does the battery actually last under heavy load?

Runtime depends on what you are cutting. Dry, thin grass lets the 20V battery run near its full rating. Damp grass or thick weeds force the motor to work harder, which can cut runtime by a third. The 40V LST136 handles damp conditions better because the PowerCommand dial lets you switch to max power without stalling. Expect 15-20 minutes of continuous heavy trimming on a standard 20V pack.

Why does my auto-feed spool jam, and how do I fix it?

Jams usually happen when the line gets tangled inside the spool or when you use line that is too thick. The AFS system needs clean, unwinding line. To fix it, remove the spool, unwind the line completely, and re-wind it tightly with even tension. Use only the recommended line diameter—typically 0.065 inches. If the line stops feeding mid-job, tap the head on the ground once to reset the mechanism.

Can I use this to edge along a brick path without scalping?

Yes, but you need to use the pivot. Rotate the trimmer head 90 degrees so the line spins vertically. Lock it in place, then walk along the path holding the trimmer at a slight angle. Keep the guard flat against the brick to set the cutting depth. Do not force the head down—let the line do the cutting. This technique gives a clean vertical edge without digging into the soil.

Will the cutting line last a full season?

No. A single spool of line typically lasts 2-4 trimming sessions depending on what you cut. Hitting concrete edges or fences dulls and breaks the line faster. Keep a replacement spool on hand. The AFS system uses more line than manual feed because it advances automatically, so you will go through it quicker than you expect.