The charger is detecting a temperature fault. Charging only initiates when the battery temperature is between 32°F and 104°F.
Fix:
- Check battery temperature. Is it in a hot garage or a cold truck?
- Move the battery and charger to an environment between 32°F and 104°F.
- Wait for the battery to naturally reach the correct temperature range.
- Re-insert the battery. Charging should start automatically.
If that didn't work, the battery may be defective. Ensure you are using a compatible M18 Lithium-Ion battery pack (Cat. Nos. like 48-11-1815, 48-11-1820, etc.).
Heads up: The charger's own operating temperature range is 40°F to 105°F. Do not charge outside these limits.