Quick answer
On the DeWalt DCB115 and DCB118, a red light that blinks continuously means charging has started, and a red light that stays on means charging is complete. A blinking red light with the yellow light on is the Hot/Cold Pack Delay: the charger waits until the pack is in range and then resumes by itself. No light at all can mean a faulty pack, but DeWalt's manual says it could also be a problem with the charger, and tells you to take both to an authorized service center.
Try our charger light-code decoder for these patterns. Everything below comes from DeWalt's DCB115 and DCB118 manuals.
LED code decoder (DCB115 and DCB118)
| LED state | What it means (DeWalt's manual) | Action |
|---|---|---|
| Red light blinks continuously | Charging has started | Wait. Completion is shown by the red light staying on |
| Red light stays on | Charge is complete; the pack may be used or left in the charger | Use the pack |
| Red light blinks and the yellow light is on | Hot/Cold Pack Delay: charging is suspended until the pack reaches an appropriate temperature | Nothing is required; charging resumes automatically |
| No light at all | The charger indicates a faulty battery pack by refusing to light. The manual adds that this could also mean a problem with the charger | Take the charger and pack to an authorized service center to be tested |
The manual shows these as graphics and never describes a "slow" or "fast" blink, a yellow-only state, or a green light. The yellow light appears only together with the blinking red.
Source: DeWalt DCB115 and DCB118 instruction manuals, page 2.
Charging temperature
DeWalt's manual says not to charge the pack in an air temperature below +40°F (+4.5°C) or above +104°F (+40°C), and that best battery life comes at 65°F to 75°F (18°C to 24°C). The 40°F lower limit is DeWalt's, not the 32°F that is often quoted.
When the charger detects a pack that is too hot or too cold, it starts the Hot/Cold Pack Delay (blinking red with yellow on) and resumes by itself when the pack is in range. If the pack still does not charge, the manual's checklist is:
- Check the outlet with a lamp.
- Check whether the outlet is controlled by a light switch.
- Move the charger and pack to a location at about 65°F to 75°F (18°C to 24°C).
- If it still does not charge, take it to a service center.
No light at all
The manual says the charger indicates a faulty battery pack by refusing to light, and that it could also be a charger problem. Its instruction is to take the charger and the battery pack to an authorized service center to be tested.
You can narrow it down before you go:
- If a different pack charges normally on the same charger, the original pack is the likely problem.
- If the pack lights normally on a different DeWalt charger, suspect the first charger.
- Check the outlet first, using the manual's lamp test above.
Why there is no green light
The DCB115 and DCB118 manuals show no green indicator. Red staying on is the complete state.
Which packs each charger takes
- DCB115: the manual says it is designed to charge DeWalt 12V to 20V Max lithium-ion packs.
- DCB118: the manual says it is designed to charge 20V Max and FLEXVOLT packs and does not describe it as a 12V charger. Check the compatibility chart at the end of the manual for your exact pack. It has a cooling fan that turns on automatically; the manual says never to run it if the fan does not work or the vents are blocked.
See our guide to which DeWalt charger you need, and our note on FLEXVOLT batteries on 20V MAX tools.
Isolating charger vs pack fault
| Scenario | Likely conclusion |
|---|---|
| A second pack charges fine on your charger | The original pack is the problem |
| Every pack shows no light on your charger | The charger is the problem |
| The suspect pack shows no light on two different chargers | The pack is the problem |
DeWalt's manual says to take both to a service center for testing, so use this table to decide what to bring, not as a final diagnosis.
If it still isn't working
Read DeWalt's current warranty terms and the terms on your product page. The DCB115 and DCB118 manuals list a three-year limited warranty. If a pack is swollen, cracked or leaking, stop using it.
For a replacement pack, see our guide to DeWalt 20V MAX replacement batteries.
View DeWalt 20V MAX XR 5.0Ah Battery (DCB205) on Amazon (paid link)
FAQ
What does a flashing red light mean on my DeWalt charger?
On the DCB115 and DCB118, a red light that blinks continuously means charging has started. Completion is shown by the red light staying on.
What does the yellow light mean on my DeWalt charger?
It appears with the blinking red during a Hot/Cold Pack Delay. The charger suspends charging until the pack reaches an appropriate temperature, then resumes automatically.
Why does my DeWalt charger show no lights when I insert the battery?
DeWalt's manual says the charger indicates a faulty battery pack by refusing to light, and that it could also mean a problem with the charger. It says to take both to an authorized service center to be tested.
Can I charge a DeWalt battery in a cold garage?
The manual says not to charge below +40°F (+4.5°C). A pack that is too cold triggers the Hot/Cold Pack Delay, so let it warm to room temperature first.
Does a blinking red light mean my DeWalt battery is bad?
No. A continuously blinking red light means charging has started. No light at all is the manual's faulty-pack indication.
Will a DCB118 charge a 12V MAX battery?
DeWalt's DCB118 manual describes it as a charger for 20V Max and FLEXVOLT packs, not 12V. Check the compatibility chart at the end of the manual before trying a 12V pack.