Best Battery String Trimmers 2026 ▷ EGO, RYOBI & CRAFTSMAN

The string trimmer is the tool that transforms a mowed yard into a finished yard. No mower reaches every corner — trees, fence lines, steps, garden bed edges, and gate posts all have grass the mower missed. A quality battery trimmer handles the entire perimeter of a typical suburban lot in 15–20 minutes, leaving the clean, finished edge that separates a well-maintained yard from a merely mowed one.

Battery technology has made the string trimmer category easier: no fuel mixing, no pull-start frustration, and battery compatibility across the rest of your outdoor tools. The three models compared here represent the best options across high performance, ecosystem value, and budget tier.

Battery String Trimmer Comparison: 2026 Top Picks

Model	Voltage	Cut Width	Line	Shaft	Battery	Best For
EGO ST1521S	56V	15 in	0.095 in	Straight	2.5Ah	Best overall
RYOBI RY40250	40V	15 in	0.080 in	Straight	Tool-only	RYOBI ecosystem
CRAFTSMAN CMCST900D1	20V	13 in	0.065 in	Curved	2.0Ah	Budget / light use

EGO Power+ ST1521S — Best Overall Battery String Trimmer

The EGO ST1521S is the best battery string trimmer in the residential market, and the POWERLOAD line system is the primary reason. Loading new line on a traditional bump-feed trimmer head is a fiddly task that many users find genuinely frustrating — threading line through small guides, winding correctly, and getting the spool back on cleanly. POWERLOAD replaces this entirely: insert a pre-cut straight line segment into the head opening, press the activation button while the trimmer is on, and the motor winds it in 5–10 seconds. When the line runs short, bump the head against the ground to advance more. When the spool is empty, reload a new line segment in seconds with no tools.

The 56V brushless motor combined with 0.095-inch line handles all normal residential trimming and moderate weed growth without hesitation. The carbon fiber split shaft is straight — appropriate for Expand-It compatible attachments (edger, pole saw, cultivator) and providing better reach under decks and low fences than a curved shaft. At 15-inch cutting width, it covers ground efficiently; a typical suburban lot perimeter takes 15–18 minutes of active trimming.

The 2.5Ah battery included in the kit is the minimum for a full trimming session on a normal lot; upgrading to a 5.0Ah provides the same battery as the EGO blower and mower, maximizing the platform's versatility. The EGO 56V ecosystem spans 60+ tools — every tool-only purchase after the first kit battery saves $100–$140.

RYOBI RY40250 — Best for RYOBI Ecosystem Users

The RYOBI RY40250 40V Expand-It trimmer is the anchor of RYOBI's outdoor power accessory system. The Expand-It compatibility is the defining feature: over 20 attachments connect to the straight shaft — edger, pole saw, pruner, cultivator, lawn aerator, snow thrower, and more — each costing $30–$80 compared to buying each tool separately. For a homeowner building out outdoor maintenance capability on a budget, one RYOBI Expand-It battery trimmer and a selection of attachments provides more total functionality than a collection of single-purpose tools.

The REEL-EASY bump-feed head is a significant improvement over older bump-feed designs: the dual-exit spool allows pulling fresh line out by hand in seconds with a single-button spool release, rather than the traditional process of removing the spool cap, pulling out a length of fused line, and re-feeding. Not as seamless as EGO POWERLOAD, but substantially less frustrating than legacy trimmer heads.

The RY40250 is sold tool-only — RYOBI assumes you already have a 40V ONE+ battery from another tool. The 40V ONE+ platform spans 80+ tools; if you own a RYOBI drill, circular saw, or any other 40V tool, your existing battery works with the trimmer. If you don't yet own a RYOBI battery, the starter kit version includes a 4.0Ah battery and charger.

CRAFTSMAN CMCST900D1 — Best Budget Battery String Trimmer

The CRAFTSMAN CMCST900D1 is the most affordable complete kit (trimmer + battery + charger) in this comparison, making it the right entry point for users who don't own a cordless tool platform and need a capable trimmer for light residential use. The 13-inch cutting width is appropriate for edging and trimming smaller lots, and the automatic line advance eliminates the need to bump-feed manually. The 2-speed selection (high torque for thick grass, standard for normal trimming) extends battery life by running the motor at appropriate power for each task.

The convertible inline edger design allows rotating the cutting head 90 degrees for sidewalk and driveway edging without a separate attachment — a meaningful addition given that edging is one of the primary tasks for a string trimmer. The 3-year CRAFTSMAN warranty provides solid coverage on a budget-tier tool.

Where it falls short: 13 inches covers less area per sweep than 15-inch competitors, adding time on larger lots. The 20V platform delivers less torque than 40V or 56V options under heavy vegetation. For weekly maintenance on a lot under 6,000 sq ft with normal grass, the CRAFTSMAN handles the job reliably. For larger lots or tougher conditions, the EGO or RYOBI is the better investment.

Battery Voltage Tiers: 20V vs 40V vs 56V Explained

Battery voltage directly determines motor torque and cutting power. The three tiers represent fundamentally different use cases, and jumping a voltage category makes a significant difference in how the tool performs under load.

20V Battery Tier — Entry Level and Light Use

The 20V class (CRAFTSMAN CMCST900D1, Greenworks tools) is engineered for light residential maintenance: weekly trimming of normal grass around a typical suburban lot under 5,000 sq ft. The 13-inch cutting width is narrow by design, trading ground coverage for lighter weight and lower cost. A 20V trimmer at full power draws about 15-18 amps; the motor spins at moderate RPM under load. On typical grass with no obstacles, the 20V performs adequately. On moderate weed growth or thick patches, you will notice the head speed drops noticeably—not stalling, but clearly working hard. The CRAFTSMAN CMCST900D1's 2-speed selection helps: running in "standard" for normal grass conserves battery and preserves runtime; switching to "high torque" for heavier growth forces more current and drains the 2.0Ah battery faster. For seasonal use (spring/summer maintenance, average 20–30 minutes per week of trimming), a 20V kit at $150–200 is economical. For year-round or frequent use, you will hit the limits of the class within 2–3 seasons.

40V Battery Tier — Mid-Range Workhorse

The 40V class (RYOBI RY40250, Ryobi Expand-It platform) is the sweet spot for serious homeowners and frequent users. At 40V, the motor delivers significantly more torque than 20V—enough to power not just the string trimmer but also the full Expand-It ecosystem (pole saws, hedge trimmers, cultivators, aerators, snowthrowers). The RY40250's 15-inch cutting width covers ground efficiently; the motor maintains head speed even on thick weeds or dense growth. With a 4.0Ah battery (the standard in the RYOBI 40V ONE+ system), you get 40–50 minutes of active trimming on typical grass, dropping to 25–35 minutes if cutting constantly through heavy vegetation. The genius of the RYOBI platform: one battery powers 80+ different tools. Upgrading from 20V to 40V in a trimmer alone may not seem dramatic, but when you factor in that a single battery runs your drill, circular saw, leaf blower, and chainsaw, the economics shift. For property owners with mixed tools or properties between 0.25 and 0.5 acres, 40V is the intelligent tier.

56V Battery Tier — Premium Performance and Reach

The 56V class (EGO ST1521S and the full EGO Power+ ecosystem) delivers the highest voltage for residential cordless equipment. At 56V, the motor is engineered with higher power output and efficiency than lower tiers. The EGO ST1521S's 15-inch cutting width and 0.095-inch line size represent aggressive specifications: the motor is designed to handle this demand without throttling. Cutting through 0.5-inch thick weeds, the EGO maintains full head speed; the RYOBI 40V will slow noticeably in the same conditions. With a 5.0Ah battery (the high-capacity option in the EGO ecosystem), runtime extends to 50–60 minutes on normal grass, still maintaining head speed through tougher conditions. The 56V EGO ecosystem spans 60+ tools: mowers, blowers, chainsaws, pole saws, leaf blowers. For property owners with large yards (0.5+ acres), significant weed challenges, or those building out a complete EGO tool collection, 56V is a long-term investment that delivers performance across your entire outdoor arsenal.

Battery Optimization and Runtime Extension

Battery life depends on three factors: capacity (measured in amp-hours), operating conditions, and storage practices. Understanding these levers extends both a single trimming session and the overall life of your battery.

Extending Runtime During Use

A 2.5Ah battery under full throttle in heavy vegetation may deliver only 20–25 minutes of active runtime. Extending that session involves matching the tool's power to the actual task. For normal grass after mowing, a 56V or 40V trimmer requires only 50–60% of maximum throttle; the line speed is still adequate for edging, and you conserve 40–50% of the battery charge. Reserve full throttle for dense weeds or obstacles requiring aggressive cutting. On 40V and 56V tools, variable-speed triggers (not all models have them, but EGO and Ryobi professional-tier tools do) enable this optimization. On 20V tools with fixed-speed or two-speed operation, running in "standard" mode for normal tasks conserves battery compared to "high torque." For back-to-back trimming sessions, a strategy common among landscapers: purchase a second battery (identical capacity) and rotate while one charges. This removes the "one battery = one session" constraint entirely.

Storage and Off-Season Care

Lithium-ion batteries (used in all modern battery trimmers) maintain charge best when stored at 40–80% state of charge and at room temperature (60–75°F). Storing a fully charged battery in a hot shed (95–110°F) or freezing garage (below 32°F) accelerates internal degradation. The ideal storage practice: charge the battery to 80% (most modern chargers have a "storage mode" that stops at 80%), place it in a cool, dry location (basement shelf, climate-controlled garage), and check it every 3 months during winter. Do not leave a battery fully discharged over winter—this can cause internal cell damage. For the CRAFTSMAN, RYOBI, and EGO platforms, a single 2.5–4.0Ah battery costs $60–90 to replace after 3–5 years of use; proper storage extends that lifespan by 1–2 seasons and preserves charge capacity.

Upgrading to Larger Batteries

Every string trimmer model is compatible with larger batteries in its voltage class. The EGO ST1521S ships with a 2.5Ah battery; upgrading to the 5.0Ah (available separately, $120–140) doubles runtime to 50–60 minutes on normal grass. The RYOBI RY40250 works with any RYOBI 40V battery: from 2.0Ah (compact, 30-minute runtime) to 6.0Ah (extended, 70+ minutes but heavier). The CRAFTSMAN CMCST900D1 accepts 2.0Ah, 4.0Ah, and 6.0Ah batteries from the CRAFTSMAN V20 line. Larger batteries weigh more (a 5.0Ah adds 1.5–2 pounds to tool weight), but on larger properties or for users who dislike mid-session battery swaps, the trade-off is worthwhile. The upgrade path is often the most economical battery expansion strategy: one higher-capacity battery eliminates the need to purchase a second 2.5Ah unit and accomplishes the same goal (extended runtime) with a lighter overall package.

How to Choose a Battery String Trimmer

The same ecosystem logic that applies to battery blowers and mowers applies here. If you already own EGO 56V tools, buy the EGO ST1521S tool-only and save the battery cost. If you have RYOBI 40V, the RY40250 tool-only is the no-brainer choice. If you're starting fresh and want only a trimmer: the CRAFTSMAN kit provides the most complete package at the lowest entry price for light residential use; the EGO kit is worth the premium for anything larger or more demanding.

The performance tier that matters most: 20V handles light weekly trim maintenance on normal grass. 40V handles moderate growth and occasional heavier conditions. 56V handles all residential conditions including moderate weeds without the motor throttling back.

Frequently Asked Questions

Frequently Asked Questions

How long does a battery string trimmer run?

Runtime varies by battery size and operating conditions. The EGO ST1521S with 2.5Ah 56V battery runs approximately 35–45 minutes of active trimming at normal speed on typical residential grass. Heavy vegetation (tall thick weeds, woody stems) at full power reduces runtime to 20–25 minutes. RYOBI 40V with 4.0Ah: 40–50 minutes on normal grass. CRAFTSMAN 20V with 2.0Ah: 25–30 minutes. For a typical residential yard where trimming takes 15–20 minutes after mowing, any of these batteries is more than adequate on a single charge. Purchase larger capacity batteries (EGO 5.0Ah, RYOBI 4.0Ah) if you have a larger property or heavy vegetation that maxes out the motor regularly.

What is POWERLOAD and why does it matter?

POWERLOAD is EGO's patented automatic line-loading system on the ST1521S. Instead of manual re-threading when the spool runs out — the fiddly task of pulling line through guides and winding it correctly that traditional trimmers require — POWERLOAD uses the motor to load pre-cut line segments automatically. You simply insert a straight piece of line into the head, press a button, and the system winds it correctly in seconds. Traditional bump-feed heads periodically tangle, fuse, or require re-threading that takes 5–10 minutes. For users who find re-threading frustrating (the most common complaint about string trimmers), POWERLOAD resolves it entirely. RYOBI's REEL-EASY head is a simpler manual alternative that is significantly easier to reload than traditional heads without being as automatic as POWERLOAD.

Can battery string trimmers handle thick weeds?

Yes, with the right specifications. The EGO ST1521S (56V, 0.095-inch line) handles weeds up to 1/2 inch thick — dandelion stocks, tall plantain, and similar garden-scale weeds. Heavy brush, blackberries, or woody stems over 1/2 inch require either a gas trimmer or an EGO-compatible metal blade attachment. The CRAFTSMAN 20V at 13 inches handles normal residential weeds at the standard residential maintenance level but will slow down on particularly heavy growth. A key indicator that you're exceeding the motor's comfortable range: the trimmer significantly reduces head speed rather than cutting through immediately. If this happens frequently, move up to a 40V or 56V model, or switch to a gas trimmer for those conditions.

Should I buy a battery string trimmer kit or tool-only?

Buy the kit (with battery and charger) for your first tool in a battery platform — it is the most economical way to get the battery. After the first kit, buy all subsequent tools as tool-only versions, which are $80–$150 less than the kit version because they exclude the battery. If you already own a 56V EGO battery from a lawn mower or blower, the EGO ST1521S tool-only version saves you the battery cost. If you own a RYOBI 40V ONE+ battery, the RY40250 tool-only version applies the same logic. Platform compatibility across your outdoor tools is the largest single efficiency gain available when building a cordless tool collection — every battery you own can run any compatible tool in that platform.

Can I use my string trimmer as an edger?

All three trimmers reviewed here can be rotated 90 degrees to use the head vertically as an edger for sidewalk and driveway edges. For the EGO ST1521S: rotate the adjustable shaft to the edger position — the design allows 180-degree shaft rotation specifically for edging. For the RYOBI RY40250: compatible with the Expand-It edger attachment (sold separately), which converts the trimmer head to a proper wheeled edger with a guide wheel for consistent depth — significantly better than freehand edging. The CRAFTSMAN has a dedicated inline edger conversion by tilting the shaft. Dedicated lawn edgers produce cleaner, more precise edges, but for typical residential maintenance trimming, the edger mode on any of these trimmers is practical and saves purchasing a separate tool.