What's the real difference between a brushed and brushless motor?

A brushed motor uses physical carbon brushes that wear down over time and create friction, generating heat and reducing efficiency. A brushless motor uses electronic switching instead, which runs cooler, lasts longer, and draws less battery for the same output. Brushless motors, like the one in the EGO ST1521S, generally cost more but hold up better under regular use.

What line diameter should I buy?

0.065 to 0.080 inch line handles typical lawn grass and light weeds. 0.095 inch or thicker is better for dense weeds and woody stems, provided your trimmer's head is rated for it. Using line thicker than your trimmer is designed for can strain the motor and reduce line feed reliability.

Do I need a trimmer with attachment capability?

Only if you're likely to add an edger, pole saw, or brush cutter down the line. Attachment-capable trimmers, common on gas models like the Husqvarna 128LD, cost a bit more upfront but can replace buying separate standalone tools later.

How long should a string trimmer last?

A well-maintained battery trimmer from a reputable brand typically lasts 5 to 8 years of regular residential use, with the battery often needing replacement before the motor does. A well-maintained gas trimmer can last 8 to 10 years or more with regular carburetor and air filter service, though gas engines require more consistent upkeep to reach that lifespan.

String Trimmers Buying Guide: Everything to Know Before You Buy

A complete buying guide to string trimmers covering power source, motor type, line diameter, attachment systems, and the maintenance each type actually requires over its lifespan.

Step-by-Step Guide

Consideration 1: Motor type

Brushless motors last longer and run more efficiently than brushed motors, at a higher upfront cost. For regular, frequent use, a brushless motor is worth the premium. For occasional light use, a brushed motor is a reasonable way to save money.

Consideration 2: Line feed mechanism

Auto-feed systems advance new line automatically or with minimal effort, a real convenience over manual bump-feed heads that require more frequent adjustment. Premium auto-feed systems, like EGO's POWERLOAD, also simplify reloading a spool entirely.

Consideration 3: Battery ecosystem, for cordless models

If you already own cordless outdoor tools, check whether the trimmer's battery platform matches. Buying into an existing ecosystem saves money on every future tool purchase in that lineup, since batteries and chargers carry over.

Consideration 4: Shaft material and adjustability

Carbon fiber shafts are lighter and stiffer than plastic or aluminum, reducing fatigue over long sessions. Adjustable or telescoping shafts help match the tool to your height and reach, particularly useful on slopes or under low branches.

Consideration 5: Attachment compatibility

If you might add an edger, blower, or brush cutter attachment later, choose a trimmer with a compatible attachment system now. Retrofitting a non-attachment-capable trimmer isn't possible.

Consideration 6: Warranty length

Warranty terms vary from 2 to 5 years depending on brand and model. A longer warranty, like the Greenworks 40V's 3-year coverage, is a meaningful hedge on a budget-tier trimmer where components are more likely to show wear over time.

A string trimmer looks like a simple tool on the surface, but the differences between models add up in ways that matter once you're actually using one week after week.

This guide covers the practical factors that separate a trimmer you'll be happy with for years from one that frustrates you within a season, beyond just power source and price.

Most of these considerations apply whether you're shopping for a battery or gas trimmer, though a few, like battery ecosystem, are specific to cordless models.

Work through each consideration below relative to how often and how hard you'll actually use the tool, rather than defaulting to the highest-spec option available.

Motor Type

Brushless motors are the more durable, efficient option and are increasingly standard on mid-range and premium trimmers, including the EGO ST1521S. Brushed motors remain common on budget models like the Greenworks 40V and keep the price down for occasional, light use.

Line Feed System

How a trimmer feeds new line matters more than most buyers expect until they've dealt with a jammed or tangled bump-feed head mid-job. Auto-feed systems reduce that friction, and premium systems like POWERLOAD remove it almost entirely.

Battery Ecosystem

For cordless trimmers, the battery platform is effectively a long-term commitment. EGO's 56V ARC Lithium, Greenworks' and Ryobi's 40V systems, and Worx's PowerShare platform are all distinct ecosystems that don't cross-compatible with each other. Choosing a platform you're likely to expand into other tools pays off over time.

Shaft Design and Attachments

Straight, adjustable shafts generally offer the best combination of reach and attachment compatibility. If attachments like a brush cutter blade or pole saw head are a possibility down the line, confirm the trimmer supports a click-on or compatible attachment system before buying.

Maintenance Expectations by Type

Trimmer type	Ongoing maintenance
Battery, brushless motor	Minimal, periodic battery care
Battery, brushed motor	Minimal, brush wear over years of use
Gas, 2-cycle engine	Fuel mixing, air filter, spark plug, carburetor upkeep