Quick answer
- On most current DeWalt 20V MAX chargers (including the DCB115), a red light blinking continuously is the normal charging indicator — not a fault. Let it finish; a solid red means fully charged.
- A blinking red with a yellow light is a Hot/Cold Pack Delay — the charger is holding off until the pack is within its safe temperature window.
- DeWalt's documented minimum charging temperature for 20V MAX lithium-ion packs is +40°F (+4.5°C) (per DeWalt's DCB115 manual). Cold packs won't charge until they warm up.
- A genuinely defective pack is usually indicated by the charger refusing to light at all when the pack is inserted — or by repeated failures after a proper warm-up and reseat.
- Check for visible damage to the battery pack, such as swelling or corrosion. If the pack is damaged, recycle and replace it.
Symptoms
When troubleshooting a DeWalt charger and pack, look for these signals:
- LED pattern: Per the DCB115 LED legend, a continuously blinking red light means Charging; a solid red light means Fully Charged; a blinking red plus a yellow indicator means Hot/Cold Pack Delay. A pack that produces no LED response at all on a known-good charger is the classic sign of a faulty pack.
- Behavior under load: If the battery is inserted into a tool, it may not power the tool, or the tool may cut out intermittently — often because the pack's protection circuit has tripped.
- Charger behavior: The DCB115 is a fanless charger, so there is no fan noise to diagnose. If you are using a fan-cooled model (such as the DCB118) and the fan runs for extended periods, that typically indicates the charger is cooling a hot pack before or during charging.
Quick checks
Before diving into deeper troubleshooting, verify these points:
- Temperature check: Ensure the battery is within DeWalt's charging window. If it's cold (below ~40°F) or hot from heavy use, let it equalize to room temperature before charging.
- Visual inspection: Look for any physical damage to the battery pack, such as swelling, punctures, or corrosion. Damaged batteries should not be used.
- Charger functionality: Test the charger with a different battery pack to confirm that the charger is functioning properly.
- Connection check: Ensure the battery is seated correctly in the charger and that the charger is plugged into a working outlet.
- Battery age: Consider the age of the battery. If it has been used extensively, it may be nearing the end of its lifespan.
- Confirm the LED legend: If you're unsure what a pattern means on your specific charger, consult the printed LED legend on the charger body or the owner's manual.
Step-by-step fix
- Remove the battery: Always start by removing the battery from the charger to ensure safety during troubleshooting.
- Inspect the battery: Check for any visible signs of damage. If the battery is swollen or corroded, it should be recycled and replaced.
- Warm (or cool) the battery: If the pack is cold, let it reach room temperature (around 70°F) before attempting to recharge. DeWalt's DCB115 manual instructs not to charge below +40°F (+4.5°C); a cold pack will sit in Hot/Cold Pack Delay (red blink + yellow) until it's within range. A hot pack needs the same patience in the other direction.
- Reseat and re-observe: Insert the pack firmly. A continuously blinking red light on its own means the charger has started a normal charge cycle — leave it alone and let it finish. Only escalate if you see no LEDs at all, or a Hot/Cold delay that never clears.
- Test with another charger: If you have access to another DeWalt charger, try charging the battery with it. This will help determine if the issue lies with the battery or the charger.
- Replace the battery: If the battery fails to charge after these steps, it may be defective. Consider replacing it with a new one, such as the DeWalt 20V MAX XR 5.0Ah Battery (DCB205), which is compatible with your tools.
View DeWalt 20V MAX XR 5.0Ah Battery (DCB205) on Amazon (paid link)
View DeWalt 20V MAX XR 5.0Ah Battery (DCB205) on Home Depot (paid link)
If it still isn't working
If the pack refuses to charge — no LEDs at all, or a persistent Hot/Cold delay that doesn't clear once the pack is at room temperature — consider the following escalation paths:
- Warranty claim: Check if your battery is still under warranty. DeWalt offers a 3-year limited warranty on their batteries. Contact DeWalt customer service for assistance.
- Service center: If the warranty has expired, take the battery and charger to an authorized DeWalt service center for further diagnosis.
- Replacement: If the battery is confirmed defective and out of warranty, purchasing a new battery may be the most practical solution.
FAQ
Why is my DeWalt battery charger blinking red?
On the DCB115 and most current 20V MAX chargers, a continuously blinking red light is the normal Charging indicator — let it run. If the red blink is paired with a yellow light, that's a Hot/Cold Pack Delay, not a fault; the charger is waiting for the pack to reach a safe temperature.
Can I charge a cold battery?
Not until it warms up. DeWalt's DCB115 manual instructs not to charge below +40°F (+4.5°C). Allow the battery to reach room temperature before charging.
What should I do if my battery is swollen?
Swollen batteries are a safety hazard and should not be used. Recycle the battery at a local drop-off location, such as Home Depot or Lowe's.
How can I tell if my charger is working?
Test the charger with a different, known-good battery. If the charger works with another battery, the original battery is likely the issue. A charger that lights up and cycles normally with a good pack is doing its job.
What is the warranty on DeWalt batteries?
DeWalt offers a 3-year limited warranty on their batteries, which covers defects in materials and workmanship.