Black and Decker LST420 Trimmer and Edger Review

Here’s another Black & Decker (or Black and Decker) classic in the form of the Black and Decker LST420 Trimmer and Edger. The Black and Decker LST420 truly is as high performance and long-lasting as advertised, especially once you take a quick look at its specs. This edger and trimmer combo device is one of the tools in the 20V Max Tool System that utilizes the same line of 20-volt rechargeable and reusable batteries as its other fellow trimming instruments. This means you’ll get to enjoy fuel economy and environmental conservation at the same time with this lawnmower. 

A Nice Cordless Trimmer

Black & Decker LST420 Trimmer and Edger is a nice cordless trimmer. You won’t have to get tangled up like helpless prey against an anaconda thanks to the edger and trimmer’s battery-based operation that eschews the need for long cords that limit the amount of lawn you can cut. You won’t have to deal with extension cords either. The trimmer features two power settings as well.

The Black and Decker LST420 is a trimmer that can be rotated so you can make use of its edger capabilities (since doing so allows the orange wheel at the bottom of the machine to be rolled along a flat surface, allowing for edging work). 

Battery Usage and Miscellany

As for the trimmer mode, you can set the unit at “one” for longer battery usage or “two” for more cutting power. The Black and Decker LST420‘s second setting allows you to make the device work like a 110-volt corded weed eater, but you have to sacrifice its battery life.

For most your trimming needs though, the first setting is enough. Unless you’re cutting stubborn weeds or you wish to do heavy-duty pruning and weed-whacking, then stick with the first trimmer mode. On a fully charged battery at “one” mode, you’ll get about 23 or more minutes of operation about 95% of the time. Then just slap on the spare battery to complete that 40 minutes to an hour left of yard work.

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Here are the specs of the Black & Decker LST420.

  • PowerDrive Transmission: This feature allows the device to receive more power from its motor and cutting string so that your landscaping endeavors can be dealt with excellently and quickly. 
  • Runtime Extension Technology: As for the Black and Decker LST420 Trimmer’s Runtime Extension Tech, it does as its name suggests. It extends runtime and ensures high performance as controlled by a dual mode accelerator switch. 
  • Automatic Feed Spool: The spool serves as your safeguard against bumps and jams as you go about your yard work.
  • Battery Packs: The entire kit comes with two 2.0-amp lithium battery packs that deliver 33% more than your average LBXR20 battery pack. 
  • 20V MAX System: The Black & Decker LST420 is part of the 20V MAX System, which is a system that ensures optimum performance and allows one battery to fit all sorts of tools.

Black & Decker LST420 Reviews

I use the Black and Decker LST420 High Performance Trimmer and Edger almost every weekend, and it’s yet to break down on me. While I do find it unfortunate that several reviewers have gotten machines that have broken down quickly, I was blessed with an optimum copy of the LST420. Ever since I’ve gotten it, I was able to make short work of the tall grass and weeds of the repossessed property I’ve recently bought for myself. Back then, the grass was about a foot tall, and the trimmer trimmed it all up like nothing. I have no complaints.

The Black & Decker LST420 20-volt Max Lithium High Performance Trimmer and Edger has received 762 reviews and has a 4.4 rating on

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As for the disappointed denizens of when it comes to the performance of the Black & Decker LST420 High Performance Trimmer, these people were mainly concerned about battery life. Certain LST420 outliers apparently had their runtime halved after only a few uses, and their owners quickly used their warranty to receive replacements.

However, some of them swapped batteries only to realize that the unit itself had problems. There are defective models of the grass cutter that quickly degrade in operating time instead of sticking to their supposed ability to work for about an hour, give or take a minute. It’s the fault of the machine or is it faulty design? The 4.4 rating suggests the former instead of the latter. 


The Black & Decker LST420 High Performance Trimmer and Edger (or at least the majority of the product that works) is a dependable trimmer/edger that works well, is comfortable to use, is easy to clean, and possesses enough power to (literally) mow down thick areas. Its runtime is supposed to last an hour as advertised on its box, so if it goes under drastically then have it replaced immediately. It’s a superb edger and it’s refreshing to not drag your extension cord all over your yard if you’re used to corded mowers. When it works, it works superbly and only a minority of its models ends up defective anyway.

Check out more best weed wacker here, and also this list here. Also, a review of the cordless weed eater.

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