Dewalt Battery Says Fully Charged But Not Working

Dewalt batteries are prevalent and reliable for everyday use in different tools. However, they are not perfect, and you might face different problems while using them. One of the common problems is the charging issue with the battery. 

Various reasons can cause the Dewalt battery says fully charged but not working. For instance, dirty terminals, wrong battery position, etc. Additionally, external factors other than the battery can cause this problem.

However, you can solve this problem by jumpstarting the battery. Another solution could be cleaning dirty terminals.

This is only basic information. You need in-detail information to learn more and a step-by-step guide to solving the issues. 

Dewalt Batteries And Their Flexibility

Dewalt Batteries usually have three voltage varieties. Their initial voltage and standard voltage according to different voltage batteries are shown below: 

Battery Voltage  Initial Maximum Voltage  Normal Voltage 
20V  20V 18V.
60V  60V 54V.
120V Lithium ION 120V (based on 2 Dewalt 60V max lithium Ion batteries combined) 108V.

The cool thing about these batteries is that they are flexible. That means you can use a 60V battery on a 20V battery. The battery will use only 20V. Similarly, you can use a 120V battery on both 20V and 60V tools

Dewalt Battery Not Charging: 4 Reasons

It can be frustrating when you’ve charged your batteries but discover that they are not working. Here are some reasons that might cause this problem:

Reason 1. Dirty Terminals 

Dirty terminals can be an issue with Dewalt batteries. If the terminals are dirty, the charger may not be able to connect to the battery. Moreover, dust in the terminals can also hamper the connectivity of the battery with tools.

So, your impact wrench or saw might not work even if the battery is fully charged. The reason could be that the tools cannot connect properly to the battery. 


Try to clean the terminals with a wire brush. This should clear the dust in the terminals and solve the issue.  

Reason 2. Improper Positioning Of The Battery

Sometimes, the problem can be pretty straightforward. You may not have placed the battery properly in the charger. 

Even if the problem is simple, it can cause you unnecessary hassle. The charger will show that your batteries are charging even if they aren’t positioned correctly.  In reality, the batteries aren’t actually charging.

Dewalt charger


Solving this problem should be easy. Make sure your batteries are seated in the charger correctly. 

When you insert the battery into the charger, look for a “click” sound. This ensures that you have positioned the battery correctly. 

Reason 3. Problem with Charger

Often, the problem is not with batteries. Instead, it actually is in the charger. If the charger is duff, Dewalt batteries will automatically shut off to protect themselves.

Also, check if, on the Dewalt charger, there is a hot-cold delay. 


If it’s really a charger problem, you shouldn’t try to keep charging the battery. Faulty chargers are likely to kill your battery. 

To solve this, simply try changing the charger and see if the problem reoccurs. 

Reason 4. Bad Or Damaged Cells

This is one of the most common issues. Your battery may have damaged cells. Having damaged cells will prevent the battery from charging.


You can follow the below steps to solve the problem: 

  • First, measure the voltage from B+ to B- terminals. 
  • Use a thermistor to check the voltage from B- to TH. The voltage should be the same as that of B+ to B-.
  • Use the thermistor again to measure resistance from B+ to TH. The resistance should be around 12000. 
  • Check the voltage of each individual cell. Measure the voltage of:
    B C1
    C1 C2
    C2 C3
    C3 C4
    C4 B+

All of the voltages should be the same.

Dewalt Battery Says Fully Charged But Not Working: Solutions

If your batteries still have the problem, you can try some other solutions. Here is what you can do: 

Solution 1. Jump Start The Battery 

When you can’t figure out the problem, you can always jumpstart your Dewalt battery. Here’s how you can do that: 

  • You need another fully charged and working battery and two short wires. 
  • Connect one end of one wire to the “+” of the working battery and the other end to the “+” of the faulty battery. 
  • Similarly, do the same with the second wire. This time, connect the negative terminals of both batteries. 
  • After connecting the second wire to the “-” side of the working battery, tap the other end of the wire to the “-” side of the faulty battery for one or two seconds. You should see a spark once you tap. Hold the wire in the terminal for a few seconds. 

You have jumpstarted your battery successfully. Your battery should work fine once you insert it into the charger and charge it completely. 

Solution 2. Contact Dewalt

If none of the above solutions works, you can try contacting Dewalt regarding the problem. 

They will try to figure out what’s wrong with the batter. If they can’t fix it, they will provide you with a new one. Dewalt is famous for its warranty on products.

However, your batteries must be below three years of use if you want to replace them.  

How To Revive A Dead Dewalt Battery?

You know what you can do when your battery is not working, even if it is charged. But what if the battery is dead?  You can follow the below steps to bring your dead Dewalt battery back to life: 

  • Make sure your battery is fully charged. You must charge the battery first for at least 12 hours if it’s not charged. 
  • You’ll need to test the voltage of the battery. To do that, you need a multimeter. If the battery has below 12 volts, then it’s not possible to revive it. It would be best if you replaced the battery. 
  • However, if the voltage is above 12 volts, you can move on to the third step. 
  • Now, you have to discharge the battery. You can connect the battery to a tool or a light bulb for around 15 minutes. 
  • After discharging, recharge the battery again for 12 hours. After you’re done recharging, the battery will be revived. You should be able to use it without any other problems. 

If the above steps don’t work, then the battery probably cannot be revived. You will need to replace or change the battery. 


How Long Does a Dewalt 20V Battery Last? 

If you keep it in good condition, a 20V battery will last you around three years. We assume that you use the battery regularly. If you only use the battery occasionally, it will last longer. 

What Does Ah Mean on Dewalt Batteries? 

Ampere-hour or Ah denotes the battery’s charge capacity. For example, a 6.0 Ah battery will deliver 6 amperes of current consistently to the tool. The battery will last about an hour if used continuously. After that, you’ll need to recharge it.

Do Dewalt Batteries Fit Other Tools?

Dewalt batteries are meant to use with Dewalt tools. These batteries have their own configuration and slots. Therefore, you can’t use Dewalt batteries with other tools. However, you can modify the battery to fit with other tools. 


Hopefully, you’ve learned the possible reasons why your Dewalt battery says fully charged but not working. The stated solutions are likely to solve the issue. 

Other than trying these solutions, you can also try a different socket to charge your battery. If the battery is not completely damaged, you’re likely to fix the issues quickly yourself. 

Good luck and have a nice day!

Robert Carlson

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