Why Your DeWalt Battery Stops Working and What You Can Do
A DeWalt battery that won't charge or hold power usually has one of three problems: the battery cells have worn out after hundreds of charge cycles, the charging contacts are dirty or corroded, or the charger itself has failed. Most of these issues can be fixed at home without tools or cost. If the battery is still under warranty, DeWalt will replace it free.
The good news is that DeWalt batteries are built to last several years of regular use, and the most common fixes take less than ten minutes. Before you buy a replacement, try the steps in this guide—you may find your battery works again.
Key Takeaways
- Clean the metal charging contacts on both the battery and charger with a dry cloth or pencil eraser, since dirt and corrosion prevent power transfer.
- Test your charger with a different DeWalt battery if you have one, because a dead charger looks identical to a dead battery.
- Let a completely drained battery sit in the charger for up to 24 hours, since some DeWalt chargers need extended time to wake a deeply discharged pack.
- DeWalt batteries typically last 3 to 5 years of regular use before the internal cells degrade beyond repair, at which point replacement is the only option.
- If your battery is less than 3 years old and still under the original warranty, contact DeWalt support with your serial number for a free replacement.
Clean the Charging Contacts First
The metal contacts where the battery meets the charger are the most common culprit. Over time, dust, dried sweat, and corrosion build up on these contacts and block the electrical connection. You cannot see the buildup easily, but it stops power from flowing.
Locate the metal terminals on the bottom of your battery—there are usually three or four small metal dots or strips. Use a dry cloth, pencil eraser, or old toothbrush to rub each contact firmly for 10 to 15 seconds. Do the same to the metal contacts inside the charger where the battery sits. Wipe away any eraser dust with a clean cloth, then try charging again.
If the contacts look visibly corroded—green or white crusty buildup—use a pencil eraser or fine-grit sandpaper (220-grit or higher) to gently scrub the corrosion away. Do not use water or liquid cleaners, which can damage the battery's internal circuits. Once the contacts are shiny metal again, insert the battery and plug in the charger.
Test Your Charger With a Different Battery
A charger can fail while looking completely normal. If you have a second DeWalt battery, insert it into the charger and plug in. If the second battery charges normally, your original battery is the problem. If the second battery also does not charge, the charger is broken and needs to be replaced.
If you do not have a second battery to test, borrow one from a friend or coworker who uses the same DeWalt platform (20V, 60V, or FlexVolt). This test takes two minutes and tells you exactly which part has failed. Many hardware stores will also test your charger for free if you bring it in.
Leave a Dead Battery in the Charger Overnight
DeWalt chargers have a safety feature that prevents them from charging a battery that has been completely drained. If your battery voltage drops below a certain threshold—usually from sitting unused for months or from being over-discharged—the charger will not recognize it.
Insert the battery into the charger and leave it plugged in for 12 to 24 hours without interruption. Some DeWalt chargers take this long to "wake up" a deeply discharged battery and begin charging. Do not unplug it to check progress. After 24 hours, remove the battery and try using it. If it holds power, the problem is solved. If it still does not charge, move to the next step.
Check the Battery Age and Warranty Status
DeWalt batteries typically last 3 to 5 years of regular use before the internal lithium cells degrade. If your battery is older than 5 years, the cells have likely worn out and cannot be repaired. Replacement is the only option.
If your battery is less than 3 years old, it is still under DeWalt's standard warranty. Find the serial number printed on the battery label and contact DeWalt customer support through their website or by phone. Provide the serial number and a description of the problem. DeWalt will send you a replacement battery at no cost if the battery is defective.
To find your purchase date, check your receipt or the original packaging if you still have it. If you cannot find proof of purchase, DeWalt can sometimes estimate the age from the serial number alone.
When to Replace the Battery Instead of Fixing It
If your battery is more than 5 years old, has been dropped or physically damaged, or has swollen visibly, replacement is safer and more cost-effective than repair. Swelling is a sign that the internal cells are failing and the battery may overheat or stop working without warning.
DeWalt batteries are sold individually or in kits with a charger. A single battery typically costs between $60 and $150 depending on the voltage and capacity. If you use your tools regularly, buying a second battery is often worth it so one can charge while you work with the other.
When you buy a replacement, keep your receipt. DeWalt's warranty covers defects for 3 years from the purchase date, and you will need proof of purchase to make a claim.
Prevent Battery Problems in the Future
Store your batteries in a cool, dry place when not in use. Extreme heat or cold shortens battery life. If you will not use a battery for more than a month, store it at about 50 percent charge rather than fully charged or completely empty.
Clean the charging contacts every few months, even if the battery is charging normally. This prevents corrosion from building up. Avoid dropping the battery or exposing it to water, both of which damage the internal circuits.
If you use your tools daily, rotate between two batteries so each one has time to rest. This spreads the wear evenly and extends the life of both packs.
Frequently Asked Questions
Can I fix a swollen DeWalt battery?
No. A swollen battery means the internal cells are failing and the battery may overheat or catch fire. Stop using it when ready and replace it. Do not try to charge it or leave it plugged in. Dispose of it at a battery recycling center or take it back to the retailer where you bought it.
Why does my charger light blink red instead of green?
A red or blinking light usually means the charger detects a problem with the battery—either it is too hot, too cold, or the cells are damaged. Remove the battery, wait 30 minutes, and try again. If the light stays red, the battery needs to be replaced. Check your charger's manual for the exact meaning of the light pattern, since it varies by model.
Can I use a different brand charger with my DeWalt battery?
No. DeWalt batteries are designed to work only with DeWalt chargers. Using a different brand charger can damage the battery or charger, or cause the battery to overheat. Always use the charger that came with your battery or buy a replacement charger from DeWalt.
How long does a DeWalt battery take to charge from empty?
A standard DeWalt battery takes 30 minutes to 1 hour to charge fully, depending on the model and capacity. Fast chargers can do it in 20 to 30 minutes. Check the label on your charger for the exact time. If charging takes much longer than normal, the battery or charger may be failing.
Is it safe to leave a DeWalt battery in the charger overnight?
Yes. Modern DeWalt chargers have built-in safety circuits that stop charging once the battery is full, so leaving it plugged in overnight will not damage the battery or charger. However, unplugging it when not in use saves a small amount of electricity.