Trimmers & Edgers
Cordless string trimmer maintenance
Four components, no engine, and one job everybody hates. Here is how to make the reload the only one you ever do.
Affiliate disclosure: we earn a commission if you buy through our links, at no extra cost to you. It never changes which product we rank first — here is how we're funded.
We have not tested these units. Every spec on this page comes from the manufacturer's own documentation and is linked to it. Every computed figure is arithmetic you can redo. Prices are checked daily — last verified January 1, 1970. Here is exactly how we pick.
A cordless string trimmer is close to maintenance-free by the standards of anything with a motor. There is no blade to sharpen, no oil, no fuel and no filter. What is left is line, a head, a guard and a shaft — and one of those four is responsible for almost every bad experience people have with the tool.
Before anything: pull the pack
The line: the only true consumable
Line is the cutting element and it is designed to wear out. How fast depends on three things, and only one of them is the tool.
| Factor | What it does | What to do about it |
|---|---|---|
| Gauge | 0.080 in breaks more readily than 0.095 in against woody stems | Match the gauge to the work; heavier for weeds, lighter for lawn edges |
| Surface contact | Concrete, curbs and stones destroy line far faster than any plant | Cut alongside hard edges, not into them |
| Head height | Letting the head touch soil abrades line and packs the head | Keep the head just above the ground and work the tip of the line |
| Line length | Over-length line loads the motor and cuts poorly | Leave the guard on -- its cutter sets the length for you |
Line gauges published for our registry: 0.095 in on the EGO ST1521S and Ryobi RY402110, 0.080 in on the Greenworks ST80L210. Full detail in the trimmer line guide.
Reloading, by head type
Automatic winding (EGO POWERLOAD)
Feed the line through, press a button, and the head winds it. EGO publishes this on the ST1521S and it is the single feature most likely to change how you feel about the tool, because manual winding is the job people put off until the trimmer is unusable.
#ad Check the EGO Power+ 15" POWERLOAD Carbon Fiber ST1521S price on Amazon — how we're funded.
Bump feed (Ryobi RY402110, Greenworks ST80L210)
Line is wound onto a spool by hand and advanced in use by tapping the spinning head on the ground. Two practical consequences: reloading is a bench job rather than a field one, and advancing line means deliberately touching the head to the ground, which is also what abrades it.
- Battery out.
- Open the head and remove the old spool and any remaining line.
- Clear packed grass from the spool housing and the exit eyelets.
- Wind the new line in the direction marked on the spool, keeping it tight and even.
- Feed the ends through the eyelets and reassemble.
- Refit the battery last, and let the guard cutter trim the length on the first run.
Winding loosely or crossing the coils is what causes the head to jam mid-job, which is the failure people blame on the tool.
#ad Check the Ryobi 40V HP Whisper 17" Carbon Fiber RY402110 price on Amazon — how we're funded.
The guard, and why it stays on
The guard does two jobs, and only one of them is obvious. It keeps thrown debris off your legs, and it carries a small cutting blade that trims newly fed line to the correct length.
Remove it for a wider cut and both jobs stop. Over-length line does not cut better; it spins slower for the same motor speed, loads the motor, and empties the pack faster. Published draws in this category are around 3.6 to 4.7 watt-hours a minute, and that figure assumes the tool is running as designed.
The shaft and the head housing
- Clear wrapped material after every session. Grass wound around the head shaft is the most common cause of a trimmer that suddenly cuts badly.
- Check the split-shaft coupling if you have one. The EGO ST1521S publishes a split carbon fiber shaft, which is also the joint that takes multi-head attachments. Keep it clean and seated.
- Do not stand the tool on its head. Support the shaft; resting a 72 inch tool on a plastic head housing is how housings crack.
- Note what the warranty covers. EGO publishes a lifetime warranty on the ST1521S carbon fiber shaft — the strongest component guarantee in our registry, and a hint about what usually breaks.
#ad Check the Greenworks 80V 16" String Trimmer ST80L210 price on Amazon — how we're funded.
Start and end of season
| When | Job | Why |
|---|---|---|
| Every session | Clear grass from the head and guard | Wrapped material is the commonest cause of poor cutting |
| Every few sessions | Check line length and reload before it runs out | Reloading mid-job with a hot head is the worst time to do it |
| Start of season | Fresh line, check guard cutter, inspect the shaft coupling | Old line stored dry can become brittle |
| End of season | Clean the head, remove the pack, store indoors | The pack is the expensive component and it does not want a cold garage |
We do not publish a battery storage temperature or charge percentage, because no manufacturer product page we cite states one. The manual that came with your pack gives the manufacturer's own figure.
What we cannot tell you
No manufacturer we cite publishes a line-life figure, a service interval, a torque spec for the head, or a storage temperature for the pack. We have not serviced any of these tools, and anything specific in those areas would be invented.
What is published: the line gauges, the head types, the split shaft, the lifetime shaft warranty and the draws these tools run at. Everything else on this page is keeping grass out of a rotating head and the guard where the manufacturer put it.
The products discussed
Specs are the manufacturer's own and linked to the page they came from. Prices come from a live daily check; where we have no verified price we say so rather than print a stale one.
EGO Power+ 15" POWERLOAD Carbon Fiber ST1521S
EGO · EGO 56V ARC Lithium · Our score 8.9/10
#ad No verified live price right now, so we show none rather than a stale one. How we're funded.
A lifetime shaft warranty and a head that reloads line at the push of a button -- the two things that actually go wrong with a string trimmer.
Published specs
| Cutting swath | 15 in |
|---|---|
| Line | 0.095 in dual-feed spiral twist |
| Head | POWERLOAD automatic winding |
| Shaft | Carbon fiber, split shaft |
| Battery (kit) | 56V 2.5Ah |
| Runtime claim | Up to 30 min on 2.5Ah |
| Charge time | 50 min |
| Warranty | 5-yr tool / 3-yr battery, lifetime shaft |
Source: POWER+ 15" POWERLOAD String Trimmer with Carbon Fiber Shaft, egopowerplus.com
56V x 2.5Ah = 140Wh. 30 minutes of published runtime from 140Wh is about 4.7Wh per minute -- roughly a quarter of what a blower on turbo burns.
What the numbers favor
- Lifetime warranty on the carbon fiber shaft, published
- POWERLOAD winds the line for you -- the job everyone hates
- 0.095 in line, the heavier of the two common home gauges
- Split shaft, so it takes EGO's multi-head attachments
What they don't
- Ships with the small 2.5Ah pack; 30 minutes is a modest published runtime
- EGO does not publish a weight for this configuration
you only edge a short driveway. An 8 in edger attachment on a power head you already own does that job better and costs a fraction.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
Ryobi 40V HP Whisper 17" Carbon Fiber RY402110
Ryobi · Ryobi 40V · Our score 8.6/10
#ad No verified live price right now, so we show none rather than a stale one. How we're funded.
67 published minutes and a swath you can dial from 15 to 17 inches -- the only adjustable-swath trimmer here.
Published specs
| Cutting swath | Adjustable 15-17 in |
|---|---|
| Line | 0.095 in bump feed |
| Shaft | Carbon fiber |
| Battery (kit) | 40V 6.0Ah |
| Runtime claim | Up to 67 min |
| Weight | 8.8 lb bare / 12.9 lb with 6.0Ah |
| Length | 72.25 in |
Source: 40V HP Brushless 17" String Trimmer (RY402110), ryobitools.com
40V x 6.0Ah = 240Wh. 67 minutes from 240Wh is about 3.6Wh per minute -- the most efficient published figure of the three trimmers here.
What the numbers favor
- 67 minutes published, more than double the EGO kit's 30
- Swath adjusts 15-17 in, so tight borders and open verge get the same tool
- Best published watt-hours per minute of the trimmers on this page
- Whisper Series noise engineering, same line as the 57 dB blower
What they don't
- 12.9 lb with the 6.0Ah pack fitted -- the heaviest trimmer here, and it is held at arm's length
- Ryobi publishes no noise figure for this specific model
- Bump feed, not an automatic reload head
you have wrist or shoulder trouble. 12.9 lb on the end of a 72 in shaft is a lot of leverage, whatever the runtime says.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
Greenworks 80V 16" String Trimmer ST80L210
Greenworks · Greenworks 80V · Our score 8.4/10
#ad No verified live price right now, so we show none rather than a stale one. How we're funded.
7.1 lb bare with a 30-minute recharge and a 4-year battery warranty -- the lightest way onto the 80V platform.
Published specs
| Cutting swath | 16 in |
|---|---|
| Motor | Brushless, 6200 RPM |
| Line | 0.080 in spiral twist dual-line bump feed |
| Battery (kit) | 80V 2.0Ah |
| Runtime claim | Up to 45 min |
| Recharge | 30 min |
| Weight | 7.1 lb without battery |
| Warranty | 3-yr tool / 4-yr battery |
Source: 80V Cordless 16" Brushless String Trimmer (ST80L210), greenworkstools.com
80V x 2.0Ah = 160Wh. 45 minutes from 160Wh is about 3.6Wh per minute, matching the Ryobi almost exactly despite half the pack size.
What the numbers favor
- 7.1 lb bare, the lightest published trimmer weight here
- 30-minute recharge, the fastest on this page
- 4-year battery warranty
- Publishes motor RPM, which neither EGO nor Ryobi does for their trimmers
What they don't
- 0.080 in line is the lightest gauge here -- it will break more often in heavy weeds
- 160Wh included is a small pack for an 80V platform
- Bump feed, not automatic reload
you cut heavy brush or thick weed stems. 0.080 in line is a lawn-edge gauge, not a bramble gauge.
How it scores
Scores are our editorial weighting of the published specs above, not a test result. They are deliberately kept out of this page's structured data.
Where to buy the tools on this page
Every link below is an Amazon affiliate link. We show no price we have not verified today, so where there is no live figure the link says "check price" and takes you to the listing to read it there.
Best overall
EGO Power+ 15" POWERLOAD Carbon Fiber ST1521S
EGO · EGO 56V ARC Lithium
Best runtime
Ryobi 40V HP Whisper 17" Carbon Fiber RY402110
Ryobi · Ryobi 40V
Best light 80V option
Greenworks 80V 16" String Trimmer ST80L210
Greenworks · Greenworks 80V
#ad As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. How we're funded.
Common questions
How do I reload string trimmer line?
Why does my trimmer line keep breaking?
Do I need to sharpen anything on a string trimmer?
How do I clean a trimmer head?
Can I remove the guard to get a wider cut?
How should I store a string trimmer?
Sources
Read next
- Trimmers & Edgers
The line gauge and the head design decide whether you enjoy this job or dread it.
- String trimmer line: gauge, shape and feed explained
Line gauge against the job, plus what automatic reload and bump feed really cost you.
- Best lightweight cordless string trimmer
7.1 lb to 12.9 lb published, on the one tool you hold at full arm extension.
- String trimmer buying guide: the four specs that matter
Line gauge, head type, shaft and loaded weight -- the four specs that decide how a trimmer feels.
- Battery lawn mower maintenance: what is actually left to do
Five maintenance jobs removed, one added. The short list that remains, and the storage habits that matter.
- Yard tool safety, from the published guidance
CDC, CPSC and extension guidance for saws, washers and mowers, in one place.