EGO Power+ ST1521S Review

Introduction: Why I Finally Made the Switch to Battery Power

I have been using gas trimmers for over a decade. The smell of mixed fuel, the pull cord that never seems to cooperate on the first try, the constant maintenance. It was a routine I accepted as part of yard work. But this season, I decided to test the EGO Power+ ST1521S string trimmer. I had heard the buzz about battery-powered tools catching up to gas, but I needed to see it for myself. So I bought this unit, charged the battery, and put it through my normal weekly routine. What I found surprised me. This trimmer is not just a compromise for the sake of convenience. It is a legitimate, powerful tool that stands on its own merits. Let me walk you through exactly what I experienced, the good and the frustrating.

How I Tested It

I did not run this trimmer through a controlled lab. I used it the way any homeowner or serious gardener would. My property has a mix of terrain. I have a standard lawn with fescue and Bermuda grass, a rocky slope along the driveway, and a fenceline that grows thick weeds and blackberry vines. I also have brick edging around flower beds that requires precise trimming. Over three weeks, I used the ST1521S for six full trimming sessions. I timed each battery run, noted how the trimmer handled different vegetation, and paid close attention to the line feed system. I also compared it directly to my old gas Echo SRM-225, which I still consider a reliable benchmark. I did not use any fancy measuring equipment. I used my watch, my eyes, and my patience.

Performance: Where This Trimmer Shines (and Where It Stumbles)

Power That Rivals Gas

The first thing I noticed was the torque. The ST1521S uses a brushless motor, and it delivers serious cutting power. I started with the grass along my fence line. That area is usually thick and damp. My old gas trimmer would bog down if I pushed too fast. The EGO trimmer cut through it without hesitation. I even let the grass get a bit tall, about eight inches, and the 0.095 inch twisted line sliced through it cleanly. The variable speed trigger is a major advantage here. I could feather the throttle for light edging along the sidewalk, then pull it fully for thick patches. The power delivery is smooth and instant. There is no lag, no sputtering. It just goes.

Runtime: The 45 Minute Claim Is Real

I was skeptical about the advertised 45 minute runtime. On my first full charge, I set a timer. I trimmed my entire front and back yard, which is about 0.3 acres of trim work, including edging. The trimmer ran for 42 minutes before the battery indicator showed one bar and the power started to drop. That is close enough to 45 minutes for me. On subsequent runs, I consistently got between 38 and 44 minutes depending on how thick the grass was. For most homeowners, that is more than enough. My gas trimmer would run for about 30 minutes on a tank, so this actually outlasts it. The battery is a 2.5 Ah unit, and it uses the ARC Lithium technology. It does not fade gradually. It runs strong until the last few minutes, then you feel a slight power reduction. That is your cue to stop.

The Variable Speed Trigger: A Game Changer

I cannot overstate how much I appreciate the variable speed trigger. On a gas trimmer, you have a fixed idle and a fixed full throttle. With the EGO, I can dial in exactly the speed I need. When I am trimming around delicate flowers, I barely squeeze the trigger. The head spins slowly and I can guide the line precisely. When I hit a patch of crabgrass, I squeeze fully and the motor roars. This control makes the tool feel more responsive than any gas trimmer I have used. It also saves battery. You only use the power you need at that moment.

Weight and Balance: Light Enough for Extended Use

At 9.5 pounds with the battery and line installed, this trimmer is noticeably lighter than my gas unit. The weight is balanced well. The motor is at the top, and the battery sits on the rear handle. This means the head does not feel heavy. I used it for over 40 minutes without my arms getting tired. The handle is padded and has a comfortable grip. The adjustable assist handle lets you rotate it for different angles. I found the balance especially helpful when edging. I could tilt the trimmer on its side and guide it along the pavement without fighting the weight.

The Line Feed System: My Biggest Frustration

Now for the part that annoyed me. The line feed on the ST1521S is not reliable. The trimmer uses a bump feed head. You tap the head on the ground to advance the line. In theory, that is standard. In practice, it often does not work. I would tap it and nothing would happen. I would tap it harder and still nothing. Then, suddenly, it would feed too much line, leaving me with a long, whipping tail that I had to cut manually. I tried different techniques. I tried tapping on concrete, on dirt, on grass. It was inconsistent. I also had issues with the line jamming inside the head. I had to disassemble the spool twice in three weeks to untangle the line. This is a known issue with many bump feed heads, but it is frustrating on a tool that otherwise performs so well. I eventually learned to pre-wind the line carefully and to tap with a firm, straight motion. It improved, but it is still not as smooth as a gas trimmer with a similar head.

Build Quality and Value

Construction and Materials

The trimmer feels solid. The shaft is a combination of aluminum and high-impact plastic. It does not flex when I push it into thick weeds. The motor housing is sealed well, and I have not seen any dust or debris getting inside. The handle assembly feels sturdy. The trigger has a positive click and does not feel loose. The battery slides into the mount with a firm lock. I dropped the trimmer once from waist height onto grass. It survived without any damage. The line head is plastic, which is standard, but it seems durable enough for normal use. The only area that feels slightly cheap is the small plastic guard that covers the line spool. It snaps on and off easily, but I worry it might crack if I hit a rock.

Battery and Charger

The battery is a 56V ARC Lithium 2.5 Ah pack. It is compatible with all EGO Power+ tools, which is a nice ecosystem benefit. The charger is a standard unit. It takes exactly 50 minutes to fully charge a depleted battery. That is the downside. If you run the trimmer for 45 minutes, you have to wait almost as long to get back to work. For large properties, you will want a second battery. The battery itself has a charge indicator with four LEDs. It is easy to check remaining power. The charger is quiet and does not get hot. I do wish the charge time was faster, but it is typical for this voltage and capacity.

Value Compared to Gas

I am not going to list a specific price because those change. But I can say this: the ST1521S is priced competitively with mid-range gas trimmers. When you factor in the cost of fuel, oil, spark plugs, air filters, and the time spent on maintenance, a battery trimmer becomes a better value over two or three seasons. You also avoid the noise. This trimmer is noticeably quieter than any gas unit. My neighbors actually thanked me. There is no exhaust smell, no need to store fuel, and no carburetor to clean. For the average homeowner, the convenience is worth the upfront cost.

Who Should Buy the EGO Power+ ST1521S

This trimmer is ideal for homeowners with medium to large lawns, up to about half an acre. If you have a small city lot, you will probably never drain the battery in one session. If you have more than an acre, you will likely need a second battery or you will be waiting for charges. It is also great for people who want to eliminate gas from their tool collection. If you already own other EGO tools, this is a no-brainer addition. The battery compatibility is a huge advantage. It is also excellent for anyone who values quiet operation. If you trim early in the morning or live in a neighborhood with strict noise rules, this is a perfect choice. The variable speed trigger makes it suitable for detailed work around gardens and flower beds. However, if you are a professional landscaper trimming eight hours a day, you will still want a gas trimmer or a commercial battery system with faster charging. The finicky line feed will also frustrate you if you demand perfect reliability every time.

My Verdict

After three weeks of real-world use, I can confidently say the EGO Power+ ST1521S is one of the best battery-powered string trimmers I have used. It delivers gas-like power without the headaches of fuel and maintenance. The runtime is honest, the variable speed trigger is excellent, and the weight makes it comfortable for long sessions. The line feed system is a weak point. It is not broken, but it is not as refined as the rest of the tool. I had to adapt my technique to avoid jams. If EGO updates the head in a future model, this trimmer would be nearly perfect. As it stands, I recommend it to any homeowner who wants a reliable, powerful, and quiet trimmer. Just be prepared to spend an extra minute or two dealing with the line feed. That small annoyance is worth the trade-off for everything else this tool offers. I have not touched my gas trimmer since I started testing this one. That tells you everything you need to know.

• Pros: Powerful cutting, honest 45 minute runtime, variable speed trigger for control, lightweight at 9.5 lbs, quiet operation, no fuel mixing or maintenance.
• Cons: Line feed is finicky and inconsistent, battery takes 50 minutes to charge, plastic line guard feels fragile.