Quick answer
- On DeWalt chargers like the DCB115 and DCB118, a continuously blinking red light actually means the battery is charging — it's normal operation, not a fault (per DeWalt's charger manual).
- A solid red light means the pack is fully charged. A blinking red light paired with a yellow light means hot/cold pack delay. A true fault is usually shown by the charger refusing to light at all, or by a distinct "problem pack or charger" blink pattern documented in your charger's manual.
- DeWalt specifies charging only between +40°F (+4.5°C) and +105°F (+40.5°C) ambient — stricter than the generic lithium-ion figure.
- Check for any visible damage on the battery pack, such as swelling or corrosion. If the pack is damaged, stop using it.
Symptoms
When you connect a battery to a DeWalt charger, such as the DCB115 or DCB118, you may observe the following LED patterns:
- Red blinking light (continuous): The charging process has started. This is the normal "charging" indicator, not a fault.
- Solid red light: The battery is fully charged and ready to use.
- Blinking red + yellow: Hot/cold pack delay — the charger is waiting for the pack to reach a safe temperature before it starts or resumes charging.
- No light at all, or a distinct problem-pack blink pattern: This is how a bad pack or a charger/pack communication issue typically presents. Consult the printed LED legend on the charger body or the owner's manual for your exact model's fault pattern.
- Behavior under load: If a pack charges to solid red but the tool fails to run or cuts out quickly, the cells may be worn or damaged even if the charger accepts them.
Quick checks
Before diving into deeper troubleshooting, perform these quick checks:
- Confirm what the LED actually means: A steady blink on a DCB115/DCB118 is charging, not failing. Let it run and come back in 30–60 minutes to see whether it transitions to solid red.
- Temperature check: Ensure the battery is within DeWalt's 40–105°F (4.5–40.5°C) charging window. If the battery feels hot, allow it to cool until it's back near room temperature before charging. If cold, warm it to room temperature.
- Visual inspection: Look for any signs of physical damage, such as swelling, punctures, or corrosion on the battery terminals.
- Charger functionality: Test the charger with a different, known-good battery to confirm that the charger is functioning correctly.
- Battery connection: Ensure the battery is seated properly in the charger, making good contact with the terminals.
- Power source: Verify that the charger is plugged into a working outlet.
Step-by-step fix
- Identify the pattern: Compare what you're seeing to the LED legend printed on the charger and in the manual. A continuously blinking red LED on the DCB115/DCB118 means the pack is charging — no action needed. The steps below apply if you have a non-charging pattern (no light, or a problem-pack blink).
- Remove the battery: Disconnect the battery from the charger before handling or inspecting it.
- Inspect the battery: Check for any visible damage. If the battery is swollen, punctured, or corroded, it should not be used and must be recycled.
- Check the charger: Use a different battery to see if the charger functions correctly. If it does, the original battery is likely faulty.
- Temperature adjustment: DeWalt instructs users not to charge below 40°F (4.5°C) or above 105°F (40.5°C). If the pack is cold, bring it indoors and let it return to room temperature before retrying. If it's hot from use, let it sit until it's no longer warm to the touch.
- Reconnect and test: After ensuring the battery is at a suitable temperature and free of damage, reconnect it to the charger and observe the LED indicator. A transition from blinking red to solid red confirms a successful charge.
- Replace the battery if needed: If the charger displays a true problem-pack pattern (or refuses to light) across multiple attempts with this specific pack, the battery is likely defective.
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If it still isn't working
If the charger still won't accept the battery — or shows a fault pattern — after following the steps above, it may be time to escalate:
- Warranty check: Review the warranty terms for your battery. DeWalt batteries typically have a 3-year warranty, which may cover defects.
- Service center: Contact a local DeWalt service center for further diagnosis and potential repair.
- Replacement: If the battery is out of warranty or deemed unrepairable, consider purchasing a new battery.
FAQ
Why is my DeWalt battery charger blinking red?
On the DCB115, DCB118 and similar DeWalt chargers, a continuously blinking red LED is the normal "charging" indicator — the charger is working. A solid red light means the pack is fully charged. A true fault is generally shown by no light at all or by a separate problem-pack blink pattern; check the LED legend on your specific charger.
Can I use my DeWalt battery in cold weather?
DeWalt specifies charging only in ambient temperatures between +40°F (+4.5°C) and +105°F (+40.5°C). If the pack is colder than that, bring it indoors and let it warm to room temperature before charging. Charging near or below the cutoff can cause permanent loss of runtime.
What should I do if my battery is swollen?
Do not use a swollen battery. It poses a safety risk. Recycle it at a designated drop-off location.
How can I tell if my charger is working?
Test the charger with a different, known-good battery. If it accepts that battery and transitions from blinking red to solid red, the charger is fine and the original battery is the likely culprit.
What if my charger shows a different LED pattern?
Refer to the specific LED legend for your charger model — patterns vary between the DCB107, DCB112, DCB115, DCB118, DCB132 and others. For example, a fast blinking red light may indicate a different issue than a steady red light.