Does the EGO ST1521S come with a battery and charger?

Yes, the standard kit includes a 56V 2.5Ah ARC Lithium battery and a standard charger. Larger battery options, 4.0Ah, 5.0Ah, and up, are sold separately and increase both runtime and total cost.

How long does the included battery run on a full charge?

Typical light to moderate trimming runs 30 to 45 minutes on the included 2.5Ah battery, depending on grass density and how much time is spent at full trigger. Heavy, dense growth reduces that runtime noticeably. For larger properties, a 4.0Ah or 5.0Ah battery extends runtime meaningfully.

What is POWERLOAD and is it worth having?

POWERLOAD is EGO's auto-feed line system that lets you feed new trimmer line into the head by pressing a button and pulling, rather than disassembling the spool. For anyone who trims regularly enough to run through line, it removes what is otherwise the most tedious part of trimmer maintenance.

Is the 56V battery compatible with other EGO tools?

Yes. EGO's 56V ARC Lithium batteries are shared across its mower, blower, chainsaw, and other outdoor power tool lines. Buying into the ST1521S makes sense as part of a broader EGO tool ecosystem, since additional tools can reuse the same batteries and charger.

EGO Power+ ST1521S Review: The Best Battery String Trimmer Overall

The EGO Power+ ST1521S pairs a 56V brushless motor and carbon fiber shaft with POWERLOAD auto-feed line. At $170 to $200, it's the trimmer we recommend most for buyers who want gas-like cutting power without the maintenance. Full review with performance notes.

Most battery trimmers ask you to choose between cutting power and low weight. The EGO Power+ ST1521S is one of the few that doesn't really force that tradeoff.

At $170 to $200 with a 56V ARC Lithium battery included, it uses a brushless motor and a carbon fiber shaft to keep the tool under 8 pounds while still holding line speed through dense grass that bogs down lighter 40V trimmers.

The standout feature is POWERLOAD, EGO's auto-feed line system. Feeding new line is a button press and a pull rather than popping the spool apart, a genuine time saver for anyone who trims often enough to run through line regularly.

Its main tradeoff is battery ecosystem. The 56V ARC Lithium platform is proprietary to EGO, and while that pays off if you're building a wider EGO tool collection, it's a real consideration if your other yard tools run on a different battery standard.

What You Are Buying

The ST1521S is a 15-inch cordless string trimmer built around EGO's 56V ARC Lithium battery system. The standard kit includes a 2.5Ah battery and charger, typically priced between $170 and $200.

The shaft is carbon fiber, which is both lighter and stiffer than the plastic or aluminum shafts common on cheaper trimmers, and it telescopes for height adjustment. The head pivots for edging, a feature not universal even at this price tier.

Performance

Everyday lawn trimming: at moderate speed, the 56V brushless motor holds line speed consistently through typical residential grass without bogging. The 15-inch swath covers ground efficiently compared with the 12 to 13-inch swaths common on budget trimmers.

Dense or overgrown patches: with 0.095-inch line installed, the motor keeps pushing through thicker growth that stalls lighter 40V trimmers. It's not a substitute for a gas trimmer or brush cutter on genuinely woody brush, but it handles overgrown lawn grass and moderate weeds well.

Edging: the pivoting head locks cleanly into a vertical position, and the motor's torque keeps the line spinning at full speed against curb edges rather than bogging down at the point of most resistance.

Battery runtime: the included 2.5Ah battery runs approximately 30 to 45 minutes of typical trimming, less in dense material. For a small to medium yard, that's generally enough for one full session. Larger properties benefit from a 4.0Ah or 5.0Ah battery, sold separately.

What It Does Well

POWERLOAD is the standout convenience feature. Line feeding on most trimmers means stopping, removing the spool, unwinding tangled line, and rewinding it correctly. POWERLOAD replaces that with feeding new line into a port and pressing a button.

The carbon fiber shaft is a genuine build quality upgrade. It's lighter than the plastic or aluminum shafts on most competitors at this price and doesn't flex noticeably even under load against thick growth.

The 56V motor's torque is the other clear advantage. It's the strongest cordless motor of the trimmers covered in this category, closing much of the performance gap with a gas trimmer like the Husqvarna 128LD.

What Falls Short

Proprietary battery platform. The 56V ARC Lithium system doesn't interchange with more common 40V tool lines from other brands. If you already own 40V tools from a different manufacturer, the ST1521S doesn't share batteries with them.

Cost for extended runtime. The included 2.5Ah battery is adequate for typical use, but larger batteries for extended sessions on bigger properties are a separate purchase that adds to the total cost.

No brush-cutter attachment. Unlike the Husqvarna 128LD, which accepts click-on brush cutter blades, the ST1521S is a string trimmer only, with no path to genuinely heavy brush clearing.

Who Should Buy It

The EGO ST1521S is right if: you want the strongest cutting performance available in a cordless trimmer, value the POWERLOAD auto-feed convenience, and are open to building an EGO 56V tool ecosystem over time.

Consider alternatives if: you already own 40V tools from another brand, need brush-cutter blade compatibility for heavy brush, or are working with a tighter budget where the Greenworks 40V or Worx WG183 cover your yard's actual needs.

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