Quick answer
- A blinking red light on your Craftsman charger can mean a fault or a temperature hold. The meaning depends on the model, so check the LED legend in your charger's manual.
- First, check the battery's temperature. If it is too hot, let it cool for at least 30 minutes.
- If the battery is cold, bring it to room temperature before charging. Most Li-ion batteries stop charging below 32°F (0°C) and may refuse to run below about 14°F (-10°C). That is normal, not a defect.
- If the issue persists after these checks, consider replacing the battery or contacting customer service.
Symptoms
When your Craftsman drill battery is having trouble, you may see:
- A blinking red LED on the charger.
- A drill that will not run under load, or that stops suddenly while in use.
Quick checks
Before deep troubleshooting, run through these:
- Battery temperature: if it is too hot, it may trigger thermal protection.
- Physical damage: look for swelling, punctures, or corrosion on the battery casing.
- Charger: use the charger made for your battery platform, for example a Craftsman V20 charger such as the CMCB104.
- Another battery: try a different battery in the drill to rule out the tool.
- Contacts: make sure the battery terminals are clean and free of debris.
Step-by-step fix
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Remove the battery from the tool before any checks, to avoid accidental activation.
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Let it cool. If the battery feels hot, set it aside for at least 30 minutes so thermal protection can clear.
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Inspect the battery for swelling or corrosion. If you find any, do not use it.
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Clean the terminals with a soft, dry cloth.
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Test the charger. Plug it in and compare the LED with the legend in your charger's manual.
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Replace the battery if necessary. If it keeps blinking red after cooling and cleaning, it may be defective.
If it still isn't working
If the charger keeps blinking red after the steps above, escalate. Check the warranty for your Craftsman battery. Craftsman lists a 3-year limited warranty on many V20 batteries, though it varies by model. If it is under warranty, contact Craftsman customer service about a replacement. If the warranty has expired, consider buying a new battery.
FAQ
Why is my Craftsman charger blinking red?
It can be a fault or a temperature hold, depending on the charger model. Check the LED legend in your charger's manual.
Can I use my Craftsman battery in cold weather?
Most Li-ion batteries stop charging below 32°F (0°C) and may refuse to run below about 14°F (-10°C). If your battery is cold, warm it to room temperature first.
How do I know if my battery is defective?
If it keeps blinking red after cooling and cleaning, and it does not charge or power the tool, it may be defective. Confirm by trying a second known-good battery.
What should I do if my charger is blinking red?
Check the battery's condition and try charging a different battery. If a good battery also fails, the charger may be the problem.
How can I extend the life of my Craftsman battery?
Avoid extreme temperatures, keep it clean, and store it in a cool, dry place when not in use.