1. Please ensure the battery installed is correct: make the +/- pole of the battery is a match the +/- pole of the charger. 2. Never mix charge different types and different capacities of batteries under the same LED indicator. 3. Using environment: 0℃ to 40℃, it is a normal phenomenon that the battery is warmer than room temperature when charging. 4. Don't disassemble or reassemble the charger by yourself for safety reasons.