Dewalt 20V String Trimmer Not Working? Easy Fixes Explained

If you’ve ever had a day set aside for yard work, only to find your Dewalt 20V string trimmer not working, you know how frustrating it can be. I’ve been there myself. You’re ready to tidy up your lawn, the weather’s great, but your trimmer refuses to start or stops after a few minutes. Over the past few years, I’ve dealt with this exact problem. I’ve learned a lot from my struggles and mistakes. In this article, I want to walk you through every step I’ve taken, the fixes that actually worked, and things I wish I’d known sooner. If your Dewalt 20V string trimmer is acting up, you’ll find real solutions here, without any technical mumbo jumbo.

My First Encounter: The Trimmer That Wouldn’t Start

I remember the first time my Dewalt 20V string trimmer decided not to work. I had just popped in a freshly charged battery and pressed the trigger—nothing. Not even a sound. I thought maybe the battery wasn’t seated right. I checked it, pressed again, and still nothing.

I’ll be honest, I felt defeated. But after a deep breath, I started checking things one by one. Here’s what I’ve learned through trial, error, and a lot of patience.

Common Reasons Your Dewalt 20v String Trimmer Stops Working

It’s easy to panic when a tool won’t start. But most problems with these string trimmers come down to a few main issues. Let me break down the usual suspects, based on my own experience:

1. Dead Or Faulty Battery

The battery is the heart of any cordless tool. If your trimmer isn’t turning on, this is the first thing to check. I learned the hard way that even if a battery looks like it’s charging, it might not have any juice. Try these steps:

• Swap in a different Dewalt 20V battery if you have one.
• Check the battery’s charge level by pressing the button on it (if your battery has this feature).
• Put the battery back in the charger. If the charger’s light blinks red, the battery could be faulty.

I once spent half an hour checking my trimmer, only to find out the battery was dead!

2. Bad Battery Contacts

Sometimes the metal contacts where the battery slides in get dirty or bent. If they’re not making a good connection, your trimmer won’t start.

• Inspect the contacts for dirt or corrosion.
• Wipe them gently with a dry cloth.
• Never use water or anything wet!

A friend of mine tried using a damp rag and ended up with a shorted battery—don’t do that.

3. Trigger Switch Problems

The trigger on the handle can wear out or get stuck. I’ve had times where I pressed the trigger and felt no resistance. Sometimes, it’s just jammed with dirt.

• Make sure the trigger springs back when you release it.
• If it feels loose, you might need a new switch assembly.
• Blow out any dust or grass clippings from around the trigger.

4. Motor Trouble

If you hear strange noises or the trimmer starts then stops, the motor could be the issue. Motors can wear out, especially if the tool gets wet or is used very hard.

• Smell for burning or see smoke? Stop using it immediately.
• Sometimes, the motor just needs a rest. Let it cool down for 10-15 minutes.

Overheating happened to me one hot summer afternoon. Letting it cool fixed the problem.

5. Spool And Line Issues

A jammed spool or tangled line can stop the trimmer from working. If the line is too long, too short, or stuck, the motor may cut out to protect itself.

• Open the spool cover and check for tangles.
• Make sure you’re using the right size line (usually .080” for most Dewalt models).
• Don’t overfill the spool.

Once, I used a thick aftermarket line, and the trimmer wouldn’t even spin. Lesson learned: stick to Dewalt’s recommendations.

6. Safety Lockout

Many Dewalt trimmers have a safety lock button near the trigger. If you don’t press it, the tool won’t run.

• Always press the safety and trigger together.
• If the lock button feels stuck, clean around it.

I can’t tell you how many times I forgot about this little safety feature, especially when in a hurry.

7. Debris Build-up

Grass and dirt can gather around the head, slowing or stopping the trimmer.

• Clean the trimmer head after every use.
• Use a brush, not water, to avoid rust.

This simple habit saved me a lot of trouble over time.

Troubleshooting Steps That Actually Work

Let me walk you through the process I follow when my Dewalt 20V string trimmer stops working. These steps come from real experience, not just the manual.

Step 1: Check The Battery

Remove the battery and try it in another Dewalt 20V tool, like a drill or blower. If it works there, the battery is fine. If not, charge it fully and try again.

Step 2: Inspect The Contacts

Look at both the trimmer and battery contacts. Clean them gently. Sometimes, a tiny piece of grass or dirt can cause a bad connection.

Step 3: Test The Trigger

Hold down the safety and squeeze the trigger. If nothing happens, try wiggling the trigger a little. Still nothing? The switch might be bad.

Step 4: Examine The Spool

Pop open the spool cap. Check if the line is tangled or jammed. If so, untangle or re-spool it according to the manual.

Step 5: Listen To The Motor

If you hear clicking, grinding, or a high-pitched whine, stop right away. This means the motor is struggling or failing.

Step 6: Let The Tool Cool Down

If you’ve been trimming for a while, the motor might be hot. Let it rest for 10-15 minutes, then try again.

Step 7: Try A Reset

Unplug the battery, wait 30 seconds, and plug it back in. This sometimes helps if there’s a small electronic glitch.

My Personal Fixes For Specific Problems

After owning my Dewalt 20V string trimmer for a few years, I’ve dealt with all kinds of issues. Here’s how I solved them—and how you can too.

Battery Won’t Charge

One day, my battery refused to charge. The charger flashed red. I thought it was dead for good, but I learned that batteries with very low charge sometimes need a “jump. ” I inserted and removed the battery from the charger several times quickly.

After a few tries, it started charging normally. This trick doesn’t always work, but it saved me from buying a new battery once.

Trimmer Starts, Then Stops

This happened to me during a big yard cleanup. It turned out the line was jammed inside the spool, and the trimmer shut off to protect the motor. I opened the spool, fixed the line, and it worked again. If your trimmer starts and stops, always check the spool first.

Motor Smells Hot

If you smell something burning, stop immediately. Let the tool cool down. In my case, I had to clean out grass clippings that blocked the air vents. After cleaning, the motor cooled better and ran fine.

Trigger Feels Loose

My trigger once felt “mushy” and wouldn’t click. Turns out, a bit of grass had gotten jammed inside. I used compressed air to clear it, and it was as good as new.

Comparing Dewalt 20v Trimmer With Other Brands

After my struggles, I got curious—were other brands any better? I borrowed a few trimmers from neighbors and did a little side-by-side test. Here’s what I found:

Based on my experience, Dewalt holds up well, especially for battery life and ease of changing the line. But it’s a bit heavier than some other brands.

Key Features That Matter Most

If you’re thinking about repair or replacement, here’s what I’ve learned to look for in a string trimmer:

A non-obvious insight: Dewalt’s interchangeable battery system is a lifesaver. I often swap batteries between my drill and trimmer. This flexibility has saved me more than once when a battery ran out mid-job.

Simple Maintenance Tips I Wish I Knew Sooner

Here are some quick things I do now, which help keep my Dewalt 20V trimmer running smoothly:

• Clean after every use. Remove grass and dirt, especially from the head and vents.
• Store the battery indoors. Extreme heat or cold can ruin batteries fast.
• Check the line often. Keep extra spools on hand, so you’re never caught off guard.
• Inspect the trigger and safety lock. If they feel sticky, clean them right away.
• Charge batteries after each use. Don’t let them sit empty for long.

A beginner mistake I made: leaving batteries in the charger for days. This can actually shorten their life. I now remove batteries as soon as they’re fully charged.

When To Call For Service Or Replace

Sometimes, a trimmer just can’t be fixed at home. If you notice these signs, it might be time to call Dewalt service or consider a replacement:

• Battery won’t charge, even after trying several outlets and chargers.
• The motor makes grinding or screeching noises.
• The trigger feels broken or won’t spring back.
• You see smoke or sparks.

Dewalt’s warranty is pretty good. I’ve used it once and they replaced my battery quickly. Keep your receipt and register your tool online.

For more details about troubleshooting battery-powered tools, you can check guides from Dewalt Support.

Frequently Asked Questions

Why Does My Dewalt 20v Trimmer Stop After A Few Seconds?

This usually means the spool is jammed or the line is tangled. Check the spool and make sure the line feeds smoothly. Also, let the tool cool down if it’s hot.

Can I Use Any 20v Battery In My Dewalt Trimmer?

Yes, all Dewalt 20V MAX batteries work with their 20V tools. However, larger batteries last longer and sometimes provide more power.

What Should I Do If The Trigger Isn’t Working?

First, check for dirt or debris around the trigger. If cleaning doesn’t help, the switch might be faulty and need replacement.

How Long Do Dewalt 20v Trimmer Batteries Last?

In my experience, a fully charged 20V battery gives about 25 to 30 minutes of trimming time, depending on grass thickness and tool load.

Is It Safe To Clean The Trimmer With Water?

No, avoid water. Use a dry brush or cloth. Water can damage the motor and battery contacts.

If you follow these tips, you’ll save time and frustration. I’ve learned a lot from my Dewalt 20V string trimmer not working. Now, it’s rare that I’m caught off guard. Keeping things simple, checking the basics, and doing regular cleaning keeps my trimmer ready for every yard job.

If your trimmer ever lets you down, don’t panic—just walk through these steps, and you’ll be back to trimming in no time.

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