Quick answer
- According to DeWalt's DCB115 and DCB118 manuals, if the charger shows absolutely no light when a battery is inserted, the charger has detected a definitively faulty battery pack.
- The charger deliberately refuses to illuminate its LEDs as a safety measure when the internal Battery Management System (BMS) logic detects an unrecoverable error, such as a dead cell or deep discharge.
- To confirm whether the issue is the battery or a dead charger, you must test the charger by plugging it into a known-working outlet and inserting a known-working battery.
- If the charger lights up perfectly fine with a different battery, your original battery pack has failed and needs to be warranted or replaced. If no batteries light up, the charger itself has failed.
- DeWalt batteries come with a 3-year limited warranty—do not throw the battery away if you purchased it recently.
Symptoms
When you insert your DeWalt 20V MAX or 60V FLEXVOLT battery into your charger (such as the DCB115 standard charger or DCB118 fast charger), neither the red nor the yellow charging LEDs illuminate. The charger appears completely dead, just as it does when it is empty and waiting for a pack.
The battery itself likely shows no bars when you press its built-in fuel gauge button.
Quick checks
Before assuming the battery is dead and needs to be replaced, run through these rapid diagnostics:
- Verify the wall outlet. Plug a lamp or radio into the exact same outlet the charger is using. GFCI outlets in garages and workshops trip frequently; the charger might simply have no AC power.
- Check the fuel gauge. Press the battery level button on the DeWalt pack. If nothing lights up, the pack is severely depleted.
- Inspect the terminals. Look inside the battery slot and the charger bay. Check if there is sawdust, dirt, or corrosion physically blocking the metal contacts from touching.
- Confirm proper seating. DeWalt batteries require a firm push to click all the way into the charger sled. If the battery isn't fully seated, the pins do not make contact and the charger will not wake up.
Step-by-step fix
If the outlet works and the battery is firmly seated but the charger still shows no light, you need to isolate which component has failed.
1. The cross-test isolation method
The quickest way to diagnose the "no light" symptom is to cross-test. Because DeWalt's manuals specifically state that no light equals a bad pack, you need to verify the charger isn't just broken.
- Test with a second battery: Take a known-good DeWalt 20V MAX or FLEXVOLT battery and slide it into the charger. If the charger begins its normal slow, red blink, the charger is perfectly fine and your first battery has suffered an internal failure.
- Test the suspect battery in a tool: Put the suspect battery into a drill or impact driver and pull the trigger. If no LED work light turns on and the motor doesn't spin, the pack is completely dead.
2. Clean the contact pins
If a pack has been sitting in a dusty truck bed, the contacts can oxidize or get packed with debris.
- Unplug the charger from the wall.
- Use a dry cotton swab, an old toothbrush, or compressed air to clean both the metal tracks on the battery and the metal pins on the charger.
- Do not use water. Isopropyl alcohol on a swab is acceptable if there is heavy grease or oxidation.
- Let it dry, plug the charger back in, and try seating the battery again.
3. Check for deep discharge lockout (sleep mode)
Lithium-ion tools will shut off before draining the battery completely to avoid permanent cell damage. However, if a completely drained battery sits on a workbench for several months, its internal self-discharge can pull its voltage below the threshold that the charger recognizes.
If the voltage drops too low, the charger will not detect a battery at all and will remain unlit. While some DIYers attempt to "jump-start" such batteries using another 20V battery, this poses significant fire risks with lithium-ion chemistry. The manufacturer-approved response for a pack that refuses to wake up the charger is replacement.
If the battery is confirmed dead:
View DeWalt 20V MAX 5.0Ah XR Battery (DCB205) on Amazon (paid link) View DeWalt 20V MAX 5.0Ah XR Battery (DCB205) on Home Depot (paid link)
If it still isn't working
If your cross-testing revealed that the charger shows no lights with any battery, and you know the wall outlet has power, the charger's internal step-down transformer or control board has failed. You will need to replace the charger.
If the issue is isolated to a single battery pack, check your purchase date. DeWalt offers a 3-year limited warranty on 20V MAX batteries and chargers, alongside a 1-year free service contract and a 90-day money-back guarantee. You can find the date code stamped on the top of the battery housing (under where the tool connects). Contact DeWalt support or take the battery to an authorized DeWalt service center for evaluation.
FAQ
Question? Is there a difference between the fast red blink and no light at all? According to the DeWalt DCB115 and DCB118 LED legends, yes. A fast red blink combined with a yellow solid light indicates Hot/Cold Pack Delay—meaning the battery is just outside the safe 40°F to 104°F charging range and will start charging once it warms up or cools down. No light at all means the charger has detected a faulty pack.
Question? Why does my DeWalt charger light work for 12V MAX but not 20V MAX? Standard chargers like the DCB115 charge both 12V MAX and 20V MAX platforms. If the charger correctly lights up and charges a 12V MAX battery but stays dead for a 20V MAX battery, the charger itself functions fine but the specific 20V MAX battery pack you are inserting is faulty.
Question? Can I fix a faulty pack that causes no light? Opening a lithium-ion battery pack is highly unadvised due to the risk of short-circuiting and thermal runaway. A pack that triggers a "bad pack" state (no light on the charger) often has one or more dead 18650 or 21700 cells internally, or a failed BMS board. It should be recycled or replaced under warranty.
Question? Do I need to buy a specific charger for FLEXVOLT batteries? No. DeWalt 60V MAX FLEXVOLT batteries are backward-compatible and will charge fully on standard 20V MAX chargers like the DCB115. However, because FLEXVOLT packs have much higher capacities, they will charge noticeably faster on the DCB118 FAST charger. Regardless of which you use, a no-light symptom means the battery is faulty.