Quick verdict
An 18V brushless string trimmer with a 15 inch swath, Ryobi's Whisper Series sound tuning, an attachment-capable shaft that takes Expand-It heads, and a 4.0 Ah battery and charger in the kit. Ryobi rates it for more power than a 21cc gas trimmer and over 40 minutes of runtime. It suits a homeowner already on the ONE+ platform with a quarter-acre of edges to keep. The caveat is that 18V is a lighter platform than 40V or 56V for thick, woody growth.
Strengths
- Brushless ONE+ HP motor on the 18V platform shared by hundreds of Ryobi tools
- Whisper Series tuning, rated by Ryobi at 89 percent quieter than gas
- 15 inch cutting swath
- Attachment capable for Expand-It and universal heads
- 4.0 Ah battery and charger included
- Over 40 minutes of rated runtime
Weaknesses
- 18V has less reserve than 40V for heavy brush and tall field grass
- Line diameter and head type are not stated in the listing
- Weight is not stated
- Attachments add cost and storage space
The overall YardToolLab Score is out of 100. Section scores are out of 10.
Who this trimmer is for
Anyone with a drawer of Ryobi ONE+ batteries has been waiting for an 18V trimmer that does not feel like a compromise. The ONE+ HP Whisper Series 15 inch trimmer is Ryobi’s answer: a brushless motor the company rates above a 21cc gas unit, a 15 inch swath, a shaft that accepts Expand-It attachments, and sound tuning that lets it run at seven in the morning. It is for the suburban quarter-acre with fences, beds and a sidewalk to edge, owned by someone already on the platform or starting on it with the included 4.0 Ah kit.
This review is based on the maker’s published specifications and on recurring owner feedback. We have not run this product ourselves.
What you get
The kit includes the trimmer, an 18V 4.0 Ah battery and a charger. Ryobi lists a brushless ONE+ HP motor, a 15 inch cutting swath, over 40 minutes of runtime on the 4.0 Ah pack, Whisper Series engineering rated at 89 percent quieter than gas, and attachment capability with Expand-It and universal heads. The listing does not state the line diameter, the head type, the shaft length or the weight; a bump-feed head is typical on Ryobi trimmers of this type, but confirm on the product page.
Cutting power
Ryobi’s claim of more power than a 21cc gas trimmer is a claim about a light consumer gas unit, and it is believable for a brushless HP motor on a 4.0 Ah pack. A 15 inch swath is the standard width for a homeowner trimmer; it clears a fence line in reasonable time without the pack drain of a 17 inch head. Owners of the HP 18V line generally describe it as a clear step up from older brushed ONE+ trimmers, fully capable of weekly lawn edging and bed trimming, and slower than a 40V trimmer once the grass is knee-high or the weeds turn woody. That is the honest ceiling of 18V and it suits most lots.
Runtime and batteries
Over 40 minutes from a 4.0 Ah pack covers a quarter-acre’s worth of edges with time to spare. Runtime shortens on the high speed setting and in heavy growth, so plan on a swap for a half-acre or a first cut of the season. The pack is the same 18V ONE+ unit that runs Ryobi drills, blowers and lights, which is the strongest reason to pick this trimmer: a second battery is probably already in the garage, and a larger HP pack stretches the runtime further.
Noise, handling and attachments
The Whisper Series tuning is the feature that changes how the tool is used. An 89 percent reduction in noise compared to gas, by Ryobi’s figure, means trimming before work or after dinner without a complaint, and no ear protection fatigue. The attachment-capable shaft splits in the middle to take an edger, pole saw, hedge trimmer or cultivator head, turning one power head and battery into a yard system; the attachments cost extra and need storage. Weight is not stated, and owners note that an 18V trimmer with a 4.0 Ah pack is lighter than most 40V kits, which helps on long fence runs.
Living with it
No gas, no carburetor, no winter stabilizer. Keep spare line on hand, clear grass from the head guard after each use, and store the battery indoors at partial charge over winter. The charger is included. Ryobi publishes separate warranty terms for the tool and the battery on the product page; read both. Expand-It attachments are stocked at Home Depot, which makes the system easy to grow.
Alternatives to Consider
The Ryobi 40V HP Brushless Whisper Series 17 inch trimmer is the step up within the same family for a larger lot and tougher growth. The EGO POWER+ ST1502SA 15 inch trimmer is the rival on the 56V platform with a Rapid Reload head and a 2.5 Ah kit. For a tiny yard, a lighter 20V trimmer-edger combo such as the Black+Decker 2-in-1 costs less and weighs less.
Verdict
Buy the Ryobi ONE+ HP 18V Whisper Series 15 inch trimmer if you own ONE+ batteries or want to start on that platform, your lot is around a quarter-acre, and quiet operation matters; the brushless motor, attachment capability and included 4.0 Ah kit make it the best 18V trimmer Ryobi offers. Skip it if the property has heavy brush or long field edges, where a 40V or 56V trimmer has the reserve 18V lacks.
Full specifications
RYOBI ONE+ HP 18V Brushless Whisper Series 15-Inch Attachment Capable String Trimmer Kit with 4.0 Ah Battery FAQs
Ryobi rates the ONE+ HP motor above a 21cc gas trimmer, which covers normal lawn edging and weekly trimming. For a field of tall grass or woody weeds a 40V trimmer with heavier line still has more reserve.
Ryobi tunes the motor and head to run far quieter than gas, which it states as 89 percent quieter. In practice it means trimming early or late without annoying neighbors.
The shaft splits to accept Ryobi Expand-It attachments and other universal attachments, so an edger, pole saw, hedge trimmer or cultivator head can share the power head and battery.
Yes. It runs on any Ryobi 18V ONE+ pack. A 4.0 Ah battery and charger are included; a larger HP pack extends runtime if you already own one.
