This charger can only charge Ni-MH/Ni-CD rechargeable battery in sizes AA or AAA, otherwise it may cause explosion, leakage, persional injury or property damage. Please ensure the battery installed is correct: make the +/- pole of the battery is match for the +/- pole of the charger. Never mix charge different type and different capacity of batteries under the same LED indicator. Using environment: 0℃ to 40℃, it is normal phenomenon that the battery is warmer than room temperature when charging.