Quick answer
- Ensure the battery is warm enough to charge; lithium-ion batteries do not charge below 32°F (0°C).
- Check for a faulty charger or battery by testing with another compatible Milwaukee battery or charger.
- Inspect the battery terminals for dirt or corrosion; clean if necessary.
- If the LED indicator shows a red blinking light on the Milwaukee M18 charger, the battery may be too hot or cold.
Symptoms
When a Milwaukee battery won't charge, you may notice several symptoms:
- The LED indicator on the charger may remain red and steady, indicating that it is not charging.
- If the battery is too hot or cold, the LED may blink red, signaling a thermal lockout.
- Under load, the tool may exhibit reduced power or stop working altogether, indicating that the battery is not supplying the necessary voltage.
Quick checks
Before diving into deeper troubleshooting, verify these quick checks:
- Temperature Check: Ensure the battery is within the operational temperature range (above 32°F). If the battery is cold, allow it to warm up to room temperature before attempting to charge.
- Charger Functionality: Test the charger with another Milwaukee battery to confirm it is working correctly. If the second battery charges, the issue may be with the original battery.
- Battery Condition: Inspect the battery for any visible damage, such as swelling, corrosion, or punctures. Damaged batteries should not be used.
- Connection Cleanliness: Check the battery terminals for dirt or corrosion. Clean them with a soft cloth or contact cleaner if necessary.
- Battery Age: Consider the age of the battery. Milwaukee batteries typically last 3 years under normal use, and older batteries may lose their ability to hold a charge.
Step-by-step fix
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Remove the Battery: Always disconnect the battery from the tool before performing any checks or maintenance to avoid accidental activation.
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Inspect the Charger: Examine the charger (e.g., Milwaukee M12/M18 charger, SKU 48-59-1812) for any visible damage. Ensure it is plugged in and functioning correctly.
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Test with Another Battery: If available, try charging a different Milwaukee battery. If that battery charges successfully, the original battery may be faulty.
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Check LED Patterns: Refer to the LED patterns for your specific charger:
- For the Milwaukee M18 charger, a steady red light indicates charging, while a blinking red light indicates a temperature issue. If the LED is alternating red/green, the battery may be defective.
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Clean the Terminals: If the battery terminals are dirty or corroded, clean them with a soft cloth or contact cleaner. This ensures a good electrical connection between the battery and charger.
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Allow Cooling/Warming: If the battery is too hot or cold, allow it to reach room temperature before attempting to charge it again. This is crucial as lithium-ion batteries have built-in safety mechanisms to prevent charging outside of safe temperature ranges.
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Replace the Battery if Necessary: If none of the above steps resolve the issue, consider replacing the battery. A reliable option is the Milwaukee M18 REDLITHIUM XC 5.0Ah Battery (SKU 48-11-1850).
View Milwaukee M18 REDLITHIUM XC 5.0Ah Battery (48-11-1850) on Amazon (paid link)
View Milwaukee M18 REDLITHIUM XC 5.0Ah Battery (48-11-1850) on Home Depot (paid link)
If it still isn't working
If the battery still won't charge after following the steps above, consider the following escalation paths:
- Warranty Claim: Check if your battery is still under warranty. Milwaukee offers a 3-year warranty on M18 batteries. Contact Milwaukee customer service for assistance.
- Service Center: If the warranty has expired, you can take the battery to an authorized Milwaukee service center for evaluation and potential repair.
- Replacement: If repair is not an option, purchasing a new battery may be necessary.
FAQ
Why won't my Milwaukee battery charge?
There are several reasons a Milwaukee battery may not charge, including temperature issues, a faulty charger, or a defective battery. Always check the LED indicators and ensure the battery is within the operational temperature range.
How do I know if my charger is working?
Test the charger with a different Milwaukee battery. If the second battery charges successfully, the charger is functioning correctly. If not, the charger may need replacement.
What does a blinking red light mean on my Milwaukee charger?
A blinking red light typically indicates that the battery is too hot or cold to charge. Allow the battery to reach room temperature before attempting to charge it again.
Can I use a different brand charger for my Milwaukee battery?
No, it is best to use the charger specifically designed for Milwaukee batteries. Using a different brand charger may not provide the correct voltage or current, potentially damaging the battery.
What should I do with a swollen battery?
Swollen batteries should never be used. Dispose of them safely at a recycling center or a retailer that offers battery recycling, such as Home Depot or Lowe's.