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How to Fix Common DEWALT Trimmer Problems

A collage of Dewalt trimmer.

DeWalt is a leader in battery tools, and its trimmer aims to impress. The DeWalt trimmer makes keeping your yard free from weeds as easy as sweeping the floor. No cord, gas, or hassles set the DeWalt trimmer above competitors.

But it does not come without some maintenance and minor problems. Here are some DeWalt trimmer problems and their solutions.

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DeWalt’s trimmer is battery powered and comes with many advantages and a small list of problems:

1. Trimmer won’t start

2. Trimmer turns off when in use

3. Battery does not charge

4. Trimmer not performing at capacity

5. Trimmer vibrates

6. Jammed up cutting line

7. Trimmer overheating

1. Trimmer Won’t Start

Man with electric trimmer trimming on garden lawn

It is frustrating when you need to do some trimming, and your DeWalt trimmer doesn’t start. Any number of problems could be the cause; luckily, most of the time, it is a quick fix.


Because the DeWalt trimmer is battery-powered, that should be the first place to look. The battery clips onto the back of the trimmer and is secured with a locking mechanism.

Ensure the battery is correctly attached and secure because a poor connection prevents the trimmer from starting. Check that the pins of the trimmer where it connects to the battery are clean.

If the battery is not charged or has a low charge, it could be the cause that the motor won’t start. Make sure the battery is fully charged by placing it on the DeWalt charger.

The charger has a red LED light that flashes while the battery is charging and constantly glows when it is full. If the LED light does not come on when you attach the battery, it could be a faulty charger or battery.

To start the motor, you must push the lock-off lever and squeeze the variable speed trigger. Ensure the lock-off lever is fully pulled back before pushing the speed trigger.

A faulty or dirty lock-off lever could cause the motor not to start. Cleaning the contact lever connections with a contact spray could restore power to your motor.

2. Trimmer Turns off When in Use

Nothing is more frustrating than trimming the lawn and the trimmer turning off halfway. If you maintain your DeWalt trimmer, this should be easy to remedy.


A low battery is the most common reason the DeWalt trimmer shuts down. Before fetching your toolkit and dismantling your trimmer, check the battery level first. The DeWalt trimmer on a full charge should give you about 30-35 minutes on its low speed and about 20-25 minutes on its higher setting.

Sometimes the running time on a full charge is misjudged, and a simple recharge could fix the problem.

The DeWalt trimmers battery life allows adequate time for most jobs. If your property needs more than 35 minutes, your trimmer is guaranteed to turn off during use. A spare battery on charge is the best solution to keep your trimmer going.

Obstruction and debris preventing the spool from turning is another possible reason for the trimmer to turn off when in use. Removing the battery for safety and cleaning the trimmer spool could resolve your problem. Removing the spool to see if there is debris inside might be necessary.

Overextending the swath on your DeWalt trimmer could cause it to turn off when in use. DeWalt recommends the trimmer swath to be 13 inches. Reducing the swath to the correct limit could fix why your trimmer turns off when in use.

3. Battery Does Not Charge

The battery is the heart of the DeWalt trimmer. If the battery does not charge, your trimmer will be useless. Finding the reason for the battery not charging could save you a lot of frustration and money.

DeWalt batteries are a little complicated, but following easy steps could help bring your battery back to life.


These four steps can assist you in discovering whether it is your DeWalt trimmer battery or charger causing your battery not to charge.

  • The first step is to ensure that your battery charger has power. Connecting another appliance to the power outlet can quickly confirm that the power outlet is working.
  • Once you are sure the charger has power, connect the battery in its charging slot to the charger. Ensure it is secure in its charging slot and has a proper connection.
  • Once the battery is properly secured in its charging slot, the charger will indicate whether the charging function is working with a red flickering LED light. The flickering LED indicates that the battery is not fully charged and is busy charging.
  • The charger will confirm that the battery is fully charged when the red LED light glows constantly. If the battery is attached to the charger and correctly secured in the charging slot, and no LED lights are flickering, the battery is most likely the cause.

DeWalt battery chargers are sensitive to temperature. Avoid placing your battery charger in an area below 40 °F or above 105 °F. Placing the battery charger at a suitable temperature could solve the problem of the battery not charging.

If the DeWalt battery charger LED lights do not come on when you charge a battery, the charger could be faulty. The easiest way to know is to get a working battery and see if the charging lights activate. If the new or other battery shows no change to the LED lights replacing or sending your charger in to be repaired is most likely the next step.

Resetting your battery can help you get it to charge. If your DeWalt trimmer battery is fully drained, it has no current to activate the charger. Here are five steps to reset your battery.

  • To get current to your dead DeWalt battery and activate the charger, you will need another DeWalt battery that is not dead.
  • The charging slots on the battery show B+ on one side and B- on the other. Put both batteries next to one another on a table or flat surface.
  • Using two short pieces of electrical wire, connect one wire to the B+ of one battery and the other side of the wire to the B+ of the other battery.
  • Take the other short wire and connect it to the B- on the one battery. Take the other side of the wire and connect it to the B- of the other battery but only for a few seconds, then remove it.
  • These steps will give the dead battery enough charge to activate the charger.
  • Most importantly, although you are working with batteries, it still carries electrical current, and taking it to be reset by a specialist if you are unsure, is the right decision.

4. Trimmer Not Performing at Capacity

Man cutting a hedge using electric trimmer,

DeWalt’s trimmer spins a 0.095 inches line up to 5800 RPM on its high setting, enough power to glide through most edges effortlessly. If you find that it is not performing as previously, there could be a problem with the cutting line, variable speed trigger, or sticky gears that prevents it from running at its capacity.


With your DeWalt trimmer constantly working to cut those tall weeds, a blocked or tangled spool could be your problem. Please remove the battery for safety, inspect the spool for obstructions, and ensure it runs freely.

If it is blocked or entangled, remove the obstruction and debris. Removing the obstruction from the spool can return the performing capacity to your trimmer.

The DeWalt trimmer has a variable speed trigger that controls at what speed the motor runs. A dirty or faulty trigger could cause the trimmer to perform poorly. If the trigger is the problem, you could try and clean it yourself, but taking it to a professional to fix it would be the best option.

A common mistake made is to replace the line with a thicker line. The recommended replacement line should be 0.095 inches. A thinner line won’t last as long but will still work and not affect the performance capacity.

Sometimes it is replaced with a thicker line accidentally or by choice to see if it will last longer. A thicker line can cause the DeWalt trimmer not to perform as expected.

The DeWalt trimmer uses gears between the motor and the spool. If debris and dust mix with the grease, the gears will become sticky and cause them to lose their smooth turning ability.

Regular cleaning and regreasing will stop sticky gears and prevent gears from breaking. Maintaining your DeWalt trimmer is essential if you want it to always perform at capacity.

5. Trimmer Vibrates

 Dewalt cordless hedge trimmer on a wooden table.

Everyone expects to get that perfect line and professional cut from A DeWalt trimmer, and a steady hand goes a long way in achieving that goal. An unexpected vibration from the trimmer could cause an uneven finish to the lawn and make it difficult to work with the trimmer. Unwanted vibration is one of the easier problems to identify and fix.


A vibration on the DeWalt trimmer could be an uneven cutting line. One cutting line shorter than the other affects the balance of the trimmer, and two possibilities could be the cause:

  1. One side of the line had a bad spot and broke, or the line contacted something sharp that caused one side to break off shorter. Extending the shortened line to an even length on both sides can eliminate the vibration.
  2. A broken or jammed-up spool can also cause an uneven line; opening the spool and cleaning any debris inside could solve the problem. If the spool is broken, replacing the spool or the broken part of the spool could rid you of the vibration problem.

6. Jammed up Cutting Line

The frustration when the cutting line shortens and the spool does not release more is a regular occurrence. A jammed-up cutting line happens when the line is too short and gets stuck inside the spool or entangles when it is too long.


Ensure that the cutting line is correctly wound in the spool. Winding it too tight or incorrectly can lead to the cutting line wedging between two lines and the spool housing bumper not releasing the cutting line. Opening the spool housing and loosening the wedged line could solve the problem but sometimes, re-winding the cutting line is necessary.

If the cutting line is not correctly re-stringed in the spool housing, it can cause the line to overextend when the motor turns. A wrongly stringed trimmer will make the cutting line too long and entangled and could cause vibrations and even jam up the spool causing the motor to stop or affecting the performance capacity. Here are the eight steps to correctly re-string your DeWalt trimmer.

  • There are two clips on either side of the spool head. Simultaneously press both clips and remove the spool head cap to reveal the leftover cutting line.
  • Remove the leftover cutting line and clean the inside of the spool head if any debris is found.
  • Reattach the spool head cap by simply snapping it back on.
  • The spool head has two notches and two eyelets. Turn the spool to align one notch with one eyelet until you can see all way through.
  • Insert one side of the cutting line into the eyelet until it goes through the spool head and comes out the other side.
  • About 10 feet of cutting line is necessary. After pushing the cutting line through the spool head, get the two ends together, leaving about 5 feet on each side.
  • Secure the back of the spool head disc with one hand, then turn the front of the spool head with your other hand clockwise to wind up the string inside.
  • Continue winding until the cutting line is the recommended 13 inches.

7. Trimmer Overheating

Close-up of electric hedge trimmer blade.

DeWalt trimmers run at 5800 RPM on its high setting, causing the motor to produce a lot of heat. The designers at DeWalt created a safeguard to prevent the trimmer from overheating. Unfortunately, overheating still happens and can cause damage to the trimmer if it is not attended to immediately.


Maintenance is the best solution to avoid overheating. Keeping your DeWalt trimmer clean should always be a priority. The trimmer has an air intake and an exhaust to release the heat inside the motor.

A clogged-up air intake could be the cause for your trimmer to overheat. The DeWalt trimmer has an air-intake filter that regularly must be cleaned to ensure proper airflow.


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