Features
- 40V MAX lithium‑ion battery with state‑of‑charge indicator
- Power Drive high‑torque transmission
- Converts from trimmer to edger in seconds
- Automatic Feed Spool (AFS) advances line as needed without bumping
- Cordless operation with included battery and charger
- Includes auxiliary handle for improved control
Specifications
Battery Included | Yes |
Battery Qty | 1 |
Battery Type | 40V MAX Lithium Ion |
Battery Amp Hours | 1.5 Ah |
Charger Included | Yes |
Charger Type | Wall‑mountable charging base |
Cordless Vs Corded | Cordless |
Voltage | 40 V (maximum initial voltage measured without workload; nominal 36 V) |
Watt Hours | 60 |
Weight | 8.9 lb |
Height | 40.5 in |
Length | 9.6 in |
Width | 4.6 in |
No. Of Batteries Required | 1 |
Gtin | 00885911487573 |
Product Application | Yard work |
Includes | (1) LST140 string trimmer/edger, (1) LBX1540 battery, (1) 40V MAX charger, (1) AF‑100 spool, (1) guard, (1) auxiliary handle |
Cordless string trimmer that converts to an edger. It uses a 40V lithium‑ion battery and includes an indicator showing remaining charge. Line is advanced automatically by the spool system, and a high‑torque transmission delivers cutting power at the string.
Black & Decker 40V MAX Lithium String Trimmer Review
Why I reached for this 40V trimmer
I wanted a cordless trimmer that could handle weekly yard touch-ups without the hassle of gas, pull cords, or extension cords. The 40V platform promised more grunt than the typical 20V homeowner tools, and the ability to flip into an edger sounded perfect for keeping sidewalks tidy. After a season of use, I’ve formed a pretty clear picture of where this trimmer excels—and where it doesn’t.
Setup and first impressions
Out of the box, assembly is minimal: attach the guard, snap on the auxiliary handle, charge the battery, and go. The included wall‑mountable charger is handy if you like a dedicated spot in the garage. The trimmer ships with a single 40V MAX (36V nominal) 1.5Ah battery and one AF‑100 spool. At 8.9 pounds with the battery, it’s light enough for most homeowners and noticeably less fatiguing than many gas models. The shaft is adjustable for length, and the auxiliary handle has enough adjustability to find a comfortable grip and maintain good balance.
The on‑tool state‑of‑charge indicator is a small but appreciated touch. Knowing how much battery is left before tackling the back fence saves a lot of guesswork.
Power and cutting performance
For a single‑line, 0.065‑inch trimmer, there’s respectable cutting authority. The high‑torque transmission does a good job transferring power to the string, and the two power settings let you tailor output to the task. On the lower setting, I can handle typical grass trimming around beds and fences while maximizing runtime. Bumping up to the higher setting helps with taller, coarser patches and grassy weeds.
Is it going to replace a commercial gas trimmer? No. But for typical suburban yards, it’s more capable than I expected. I’ve cut through weeks‑old growth along a fence line without babying it, and it didn’t feel starved for torque.
One important note: while it’s advertised as a 13‑inch cut, the single‑line head doesn’t feel like a full 13 inches in real‑world use. If you’re used to dual‑line, 0.080‑inch heads chewing through a wide swath, this will feel narrower and slower. You can still get clean results—it just rewards a steady pace.
Edging performance
Converting to an edger is quick—rotate the head and you’re in. For occasional touch‑ups, the edging mode is perfectly serviceable. It’s especially effective along softer turf edges where you’re cleaning up overgrown grass on hard surfaces.
For long edging runs, the limitations show. There’s no support wheel; you’re guiding the tool freehand. The pop‑out edge guide helps you find the line, but it doesn’t carry the weight or keep a perfect path. If you’re used to a dedicated wheeled edger, expect more finesse work from your arms and wrists. I can keep a reasonably straight cut along a driveway, but it’s more effort and concentration than a tool purpose‑built for edging.
Line feed and spools
The Automatic Feed Spool (AFS) mostly does what it promises: advance line without bumping. It’s convenient and keeps the head off the ground, which helps protect the guard and prevents scalp marks. That said, there are moments—especially after cutting heavy patches—when I wish I could bump to get an instant length refresh. The AFS usually catches up after a brief pause or a restart, but the lack of a manual backup is noticeable.
Spool changes are painless and truly tool‑free. The head accepts AF‑100 spools, which are widely available. Keep at least one spare on hand; if you’re doing a mix of trimming and edging, you can go through line faster than you’d think.
Battery and runtime
The included 1.5Ah pack is the right size to keep the tool light, but it sets your expectations on runtime. Working at the lower power setting, I can tidy up front and back yard edges and around obstacles in one go. Add heavier growth or extended edging, and I’m looking for the charger sooner.
A few practical observations:
- Light, frequent trimming maximizes runtime. Quick weekly passes are the sweet spot.
- Heavy cutting and sustained edging drain the pack faster. Plan to charge or pause.
- The tool’s power electronics are good about protecting the battery. If you bog down the head with vines or thick weeds, it will shut off rather than cook the pack; clear the jam and restart.
If you have more than a modest yard, I’d budget for a second battery—ideally a higher‑capacity pack in the same platform. The charger is compact and straightforward; charge time is reasonable for a homeowner tool, but topping up mid‑job isn’t ideal.
Ergonomics and noise
Ergonomically, this trimmer hits a nice balance. The adjustable shaft and handle make it easy to set up for different user heights. Weight distribution is better than many battery trimmers; the head isn’t overly heavy, and the battery counterbalances decently.
Noise is higher than many expect from battery tools. It’s not thunderous, but it’s a sharp, high‑pitched whir at the head that carries. I still wear hearing protection, and I wouldn’t count on it being a “quiet hours” tool.
Vibration is low, especially compared to small gas units. After a full session, my hands aren’t buzzing, which makes it easier to maintain steady technique.
Maintenance and ownership
Maintenance is refreshingly simple:
- Keep a clean guard and head; clippings accumulate fast, especially in damp grass.
- Inspect the spool and line condition; old, brittle line feeds poorly.
- Store the battery at partial charge if you’re putting it away for a while, and avoid leaving it on the charger for days.
Everything about the design favors low‑effort ownership. There’s no carb to winterize, no fuel to mix, and no exhaust fumes. Long‑term, your costs are line, occasional spools, and potentially an extra battery.
What I’d change
A few tweaks would elevate this tool:
- Add a bump‑feed backup. AFS is convenient, but a manual override would solve the occasional “short line” moments.
- Include a support wheel for edging. Even a small, adjustable wheel would improve straightness and reduce fatigue on long runs.
- Ship with a higher‑capacity battery option. The 1.5Ah pack keeps weight down, but many homeowners would trade a few ounces for more runtime.
Who it’s for
This trimmer is a strong fit if you:
- Want cordless convenience for routine yard maintenance.
- Have a small to medium yard and trim weekly.
- Prioritize light weight, simple controls, and fast setup over raw cutting width.
- Plan to edge occasionally, not as a primary task.
It’s not ideal if you:
- Regularly cut dense weeds, tall brush, or neglected areas.
- Need long, straight, professional‑looking edges every week.
- Expect a full 13‑inch dual‑line performance in thick growth.
The bottom line
The 40V trimmer delivers what most homeowners need: enough power to keep grass edges in check, easy line changes, cordless freedom, and a body that won’t beat you up over a Saturday morning. It’s honest about its limitations: a single‑line head, a smallish included battery, and an edging mode that’s best for touch‑ups rather than marathon sessions. The state‑of‑charge indicator, adjustable shaft, and well‑mannered balance make it a genuinely pleasant tool to live with.
Recommendation: I recommend this trimmer for homeowners with small to medium yards who value convenience and low maintenance over maximum cutting width and pro‑grade edging. Pair it with a second battery if your trimming runs long, keep spare spools on hand, and you’ll have a reliable, easygoing yard companion. If your yard routinely throws heavy brush or long edging runs at you, consider a higher‑voltage system or a dedicated wheeled edger instead.
Project Ideas
Business
Curb-Edge Refresh Service
Offer a fast, quiet edging and trimming subscription for small yards, townhomes, and HOAs. Promote 20–30 minute touch-ups using a cordless, low-noise tool, with before/after photos and tiered frequencies (weekly/biweekly/monthly).
Real Estate Curb Appeal Blitz
Partner with agents to deliver same-day front-yard cleanups before showings: crisp edges along walks/driveways, trimmed beds, and tidy borders. The battery indicator helps schedule multiple stops per charge; include a brief photo report for listings.
Cemetery Marker Care
Provide respectful, low-noise trimming and edging around headstones and borders. The lightweight cordless trimmer is ideal for tight spaces without fumes. Sell seasonal packages and text photo confirmations to out-of-town families.
Youth Sports Field Edging
Maintain sharp grass edges along baseball baselines, soccer sidelines, and spectator areas. Use edger mode for clean lines and the trimmer for fence lines and dugout perimeters. Offer pre-season and weekly maintenance bundles.
Pop-Up Lawn Logos
Create temporary lawn logos and monograms for schools, teams, and events by trimming/edging shapes and optionally overlaying removable field chalk. Market to booster clubs and event planners; price by size and complexity.
Creative
Lawn Labyrinth
Lay out a simple labyrinth or maze with string, then use the edger mode to score clean borders and the trimmer to open the walking paths. The cordless 40V battery and state-of-charge indicator make it easy to pace the build, while the AFS keeps the line feeding for continuous shaping.
Backyard Mini-Golf
Design 3–6 mini-golf holes by trimming fairways short and cleanly edging greens and obstacles. Use the edger mode to define cup rings and borders around pavers or pallets. The high-torque transmission helps cut thicker patches, and the auxiliary handle provides control for precise arcs.
Negative-Space Garden Art
Create silhouettes by placing flat cutouts (letters, animal shapes) on the lawn and trimming around them to leave darker, taller contrast. Switch to edger mode to crispen outlines. Great for seasonal displays or kids’ names along a fence line.
Herb Spiral and Bed Accents
Outline an herb spiral or geometric beds with the edger, then trim the interior paths low for visual depth. The cordless setup lets you move freely as you refine curves, and the automatic feed spool helps maintain consistent cuts around tight turns.
Event Monograms on Grass
Use cardboard stencils to lightly trim down letters or numbers for weddings, birthdays, or school events. Edge the perimeter for crisp definition, then optionally dust with temporary lawn-safe chalk for contrast. Quick to install and remove.