Why Your Dewalt Battery Says Fully Charged But Not Working?

Even though your Dewalt battery is fully charged, it stops working. Despite being fully charged, your Dewalt battery might not work.

So, why does the Dewalt battery say fully charged but not working?

Dewalt batteries stop working due to an overheated battery, low voltage, wrongly seated battery, or when the battery is dead. All these could cause the Dewalt battery to not work even if it shows fully charged. These problems are fixable with a few steps unless the Dewalt battery is completely dead.

But don’t worry, I have years of experience in this field, so I’ve mentioned all the solutions to these problems in this article. So, keep reading to learn more!

Troubleshooting Dewalt Battery Says Fully Charged But Not Working

The Dewalt battery is known to have a long life and be very reliable. However, like any other battery, it can have problems from time to time. Here’s a table listing the problems and their solutions. You will know why the Dewalt battery says fully charged but isn’t working.

Problems	Solutions
Connect the battery to another battery	Seat the battery properly
The voltage is too low	Reset and charge the battery
The Dewalt Battery is dead/Terminals are dirty	Jumpstart the battery
Dewalt Battery is dead/Terminals are dirty	Clean the contacts on the battery
	Charge the battery slowly with small boosts
	The Dewalt Battery is dead/Terminals are dirty
	Connect the battery to an AC adapter
	Replace the battery

Reason 1: The Battery isn’t fully seated

Your Dewalt battery might not be seated all the way if you are experiencing this problem. It won’t be possible for the Dewalt chargers to charge a battery that isn’t fully seated.

Solution:

The solution is quite simple, just seat the battery fully. Make sure you insert it all the way. It will feel like it clicked when it is fully inserted.

Reason 2: The battery is overheated

The Dewalt battery might have problems related to charging. A common reason is battery overheating. An overheated battery can be dangerous if left alone. So, you need to fix it as soon as possible.

Solution:

To resolve power issues with your tool, remove the battery by pressing the release button. Place it in the charger for a full 8 hours( or charge the battery overnight for a full charge) to reset the battery. If problems persist, consider replacing it with a new battery instead of attempting to revive it.

Reason 3: Voltage is too low

Your Dewalt battery won’t have enough power to work if the voltage is too low. You need to check why your Dewalt 20v battery is charged but not working. The voltage needs to be higher than 15v for a 20v battery.

How to check:

You can check the voltage of your Dewalt batteries in these simple steps:

Required tool: Voltmeter 

Step 1: Firstly, measure from the battery’s B+ to B- terminals to check the voltage.

Step 2: For the first thermistor check, measure from B- to TH to check the voltage. It should be the same as the measurement from step 1.

Step 3: For the second thermistor check, measure from B+ to TH to check the resistance in Ohms. It should measure around 12,000.

Step 4: If the previous measurements were all correct, you need to test the individual cells. Measure the cells in the following way

B- to C1 = ?v
C1 to C2 = ?v
C2 to C3 = ?v
C3 to C4 = ?v
C4 to B+ = ?v

There shouldn’t be more than a 100th of a volt difference between any two results.

If all the measurements are good, it means your battery’s voltage is high enough. Then the voltage isn’t the issue. If the voltage isn’t high enough, then move on to the solution.

Solution:

If your voltage is too low, jump-start the battery following these steps:

Step 1: First, get a working battery with a full charge and 2 short wires.

Step 2: Connect the dead Dewalt battery’s positive (+) terminal with the charged battery’s positive (+). Use a good quality jumper wire to connect them.

Step 3: Tap the other wire on the other terminal of the dead battery for half a second. Don’t tap it for any longer or you can risk a fire.

Step 4: Keep repeating the last step until you get a voltage high enough, such as 60 volts.

This should raise the voltage of the battery enough to work again.

Reason 4: Battery is dead

Lastly, it could just be that your Dewalt battery is dead but the charger says full. Because of the dead Dewalt battery, there are also problems like lawn mower flashing red light. 

You could attempt to revive it in a few ways to see if it works again. First, you need to confirm whether the Dewalt battery is really dead or not.

How to check:

You can check if your Dewalt batteries are dead or not in the following ways:

1. Connect the charger to a power source and insert the battery. Check the Dewalt battery indicator to see if it shows charge or not, indicated by the red light. It will flash, show yellow light in between, and such to indicate problems.

2. As mentioned before, check the voltage to see if the battery has enough voltage or not. Too low voltage like lower than 18V means that the battery is dead.

Solution 1:

The first solution is to clean the contacts. You can clean the contacts in 2 different methods.

For dirty contacts, clean them in the following way:

Step 1: Wipe the battery’s contacts with a clean and dry rag. Make sure to remove all sorts of dirt from them.

Step 2: Next, try charging the battery after cleaning to see if it works now.

For rusty contacts, clean them in this way:

Step 1: Use fine-grit sandpaper to scrub the battery’s contacts softly. Get rid of all the rust on the contacts.

Step 2: Again, connect the battery to the charger to see if it works.

Solution 2:

The next solution is to slowly charge the battery with mini boosts. Here are the steps to follow:

Step 1: Choose a power source and then connect your battery to it for 3 seconds at a time.

Step 2: Disconnect after 3 seconds, right before the battery’s lights come on.

Step 3: Repeat the steps for up to 30 minutes at least. You should have enough power by then.

Solution 3:

You can also use an AC adapter to revive the battery in the following way. This process is called resuscitation. 

Step 1: Find an AC adapter that matches the voltage and amperage of the dead Dewalt battery.

Step 2: Unplug your AC adapter and cut its end using an insulated tool.

Step 3: Separate its wires and take off 1” of each of the wires. There’ll be a black and a white wire.

Step 4: Remove your battery pack’s case after unscrewing it with a thin screwdriver.

Step 5: Now, connect the adapter to an outlet.

Step 6: Connect the adapter’s wires to the matching terminals of the dead battery for 1 minute.

Step 7: Afterwards, put the battery’s case back on and charge it normally.

Step 8: If it still doesn’t charge, repeat the charging process again.

Follow the steps carefully and in the correct order. Your battery should work fine now.

Frequently Asked Questions (FAQs):

Conclusion

Hope this article will help you to solve all your problems regarding the Dewalt battery says fully charged but not working. Always remember to be extra careful when charging with open wires as it can easily catch fire.

Feel free to share in the comments your experience and how you solved your problem!

Till next time!