EGO Carbon Fiber String Trimmer Review | ST1521S

EGO Carbon Fiber String Trimmer
PTR Review
  • Pro Review 9.6
Overall Score 9.6 (out of 10)

In September of 2018, we had the pleasure of talking with Kyle Selph, a product manager from EGO . This took place at our ProToolReviews home office. We always look forward to these visits because we often get to preview new EGO products. This trip was no exception, and we got our hands on the latest EGO Carbon Fiber String Trimmer with an Auto-Feeding Powerload Head (model ST1521S). It’s the only technology of its kind and removes a major pain point in reloading string. We’ve now officially reviewed this battery-powered trimmer and even compared it to other models in our latest best battery-powered weedeater roundup .

Cordless trimmers have steadily improved over the years with their power and runtimes. While the new model was no slouch in these areas, it seems clear that EGO aimed for improvement in the user experience. They also dramatically increased the durability of the product. There are “things to write home about” with this new product: A new carbon fiber shaft and an auto-feeding Powerload trimmer head.

Talkin’ Shaft on the EGO ST1521S

One of the notable features that our team got super stoked about is the carbon fiber shaft. EGO found a way to bring landscape tool users into the world of lightweight, strong, and durable carbon fiber. The benefits of a lighter and tougher shaft ought to be obvious to anyone who has ever picked up a string trimmer or pole saw. Carbon-fiber delivers a nearly impossible-to-break shaft that weighs far less than steel. It alleviates the stress on your back when using this tool for an hour at a time. Plus, EGO states the carbon fiber shaft is so durable that they put a lifetime warranty on it.

EGO Carbon Fiber String Trimmer

However, weight distribution plays a big part in how comfortable the string trimmer actually feels. The feather-light shaft doesn’t mean a whole lot if the trimmer is unbalanced. You wind up having to physically overcompensate by keeping the heavy side lifted up. Thankfully, EGO addresses this too. The handle placement provides a central point that balances the heavier parts really well. Several of us put the EGO Carbon Fiber String Trimmer through its paces for well over an hour each, and none of us needed a bottle of Tylenol or a stiff drink afterward.

EGO Carbon Fiber String Trimmer

Auto-Feed Me, Seymour

The other really notable feature of the new EGO Carbon Fiber String Trimmer is the Powerload auto-feeding head. Anyone who has wrestled with loading fresh line into a string trimmer head understands this. Some systems work better than others—but none work as easily as the Powerload system.

EGO has fixed this. Instead of taking apart the head—or even winding it manually—you simply feed the 0.095″ line through one of the holes and pull it out the other end. Then, you pull the ends even so that the line centers up. Finally, the magic happens. As you hold down the button on the back of the motor, the Powerload head ratchets the line up evenly. And the best part? The whole process takes about 10 seconds.

EGO has even optimized the speed to ensure that you don’t easily overwind the line or whip yourself in the face as it spools up. I don’t know about you, but I appreciate not being flogged by my string trimmer! This system completely revolutionizes how you load your string—we love it.

EGO Carbon Fiber String Trimmer Features

The EGO Carbon Fiber String Trimmer also features a free-spinning bumper on the head. The bumper spins separately from the head itself. This reduces wear on the part and is also helpful for folks who prefer to slide the head across the ground while trimming. We noticed that the head “rolls” very well, offering less resistance against the grass.

EGO Carbon Fiber String Trimmer

This new model also features a side trigger safety control. Basically, you’ll need to hold down the safety switch on the side to pull the trigger and start the motor. Thankfully, it’s easily accessible with the thumb though it makes the tool a bit right-hander friendly.

EGO Carbon Fiber String Trimmer

EGO’s new trimmer also features a 15″ cutting swath, variable speed control, and a long-lasting and powerful brushless motor.

Shhhh! Super-Quiet Trimming

We tested dozens of string trimmers and the EGO Powerload model with carbon-fiber shaft is the quietest. At the ear, our SPL meter showed it at just 80 dB(A). That’s quiet enough to trim at 5am and not wake the neighbors… Other trimmers are right behind this, but we love the quiet trend of battery-powered outdoor power tools.

We also felt less vibration in this model compared to most others. It’s easy on the hands, and even after hours of use, we didn’t feel our hands go numb as they do with some other models.

EGO ST1521S edging


The EGO Carbon Fiber String Trimmer runs $229 for the kit, which includes a 2.5Ah battery and charger. For those of you already on the EGO battery platform, the bare tool is available as well. It retails for $169. The trimmer comes with a 5-year limited warranty.

The former model was $30 less for the kit without the carbon fiber shaft and Powerload head (it had a Rapid Reload head). While more expensive than many residential battery-powered string trimmers, this model has the features to back up the premium price. EGO also has an advantage in weight, balance, and vibration. So it’s really a wonder why you’d pull the trigger on something else.

What About Power?

Innovation is great, but if the string doesn’t cut, the rest doesn’t matter. EGO rates their latest string trimmer for both 0.080″ and 0.095″ line and it comes pre-spooled with 0.095″. We recommend you stay with the thicker line. The Powerload trimmer handles it well and you get better cutting and durability.

In our testing, there’s just not a lot to complain about. The handle could stand to be a tad stiffer and larger—a small ding on an otherwise superb product. The power and balance are as solid as the previous model and there’s a noticeable weight difference in favor of the new carbon-fiber shafted model. So from where we stand, EGO took an already great product and made it better while remaining the best value in the cordless string trimmer game.

EGO ST1521S Trimmer Features

  • EGO Carbon Fiber String TrimmerAuto-wind head, load your line, push a button and go
  • Carbon fiber shaft with a lifetime warranty
  • 15-inch cutting swath
  • Dual-feed spiral twist 0.095 in. line
  • Hi-efficiency brushless motor
  • Variable speed control
  • 5-year limited warranty
  • MSRP: Around $229 , includes 2.5Ah battery and 56-Volt charger
  • Also available as a bare tool for around $169

Ego Carbon Fiber String Trimmer Specs

  • EGO ST1521S weedeaterModel: ST1521S (kit)
  • Max cutting diameter: 15 in.
  • Head: Cartridge with Powerload
  • Automatic bump line advance
  • Line diameter (max): 0.095 in.
  • Shaft: Straight 42 in. carbon fiber
  • Battery: 56V 2.5Ah Lithium-ion
  • Dimensions (LxHxW): 71.8 x 4.4 x 7.8 in.
  • Weight: 11.97 lbs.


The EGO 15-inch Powerload string trimmer with PowerLoad is unlike anything else on the market. The carbon fiber shaft drops the weight while providing plenty of strength and rigidity. Quiet, powerful, and well-designed, this string trimmer currently leads the playing field. We also love that, once you get on the EGO platform, you gain access to their Select Cut lawn mower , Peak Power lawn mower, 56V hedge trimmer, and other tools.

For more information about the new EGO Carbon Fiber String Trimmer With The Powerload Head, check out . To purchase this product, click here .

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Melvin Love

best battery operated trimmer ever but when you have a problem customer service is the worst ever, needed help for a month but no response.


Trim line doesn’t feed through to the other side and the bump advancer never works. The line always winds tangled. It’s very frustrating.

Fred S.

Purchased an ST1500SF after extensive research on 8/5/20. Approx 5 days later, began using it, ran smoothly and silently for about 20 minutes. Then it would not feed string. With difficulty, removed the head and removed the tangled line and reloaded it. Will see how it operates now. I agree with previous correspondence in that customer service is difficult co contact!!

Bob Hojjs

A big weight difference?? That’s not what it feels like in store and the specs don’t list a large difference either. Where did they get that?

Bill Dreyer

Can I use the pole saw attachment on my EGO ST1520 S/ST if no do I have to buy the other power head?

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