The Charger can charge 1-4pcs AA/AAA/9V Ni-MH/Ni-Cd rechargeable batteries. Charging by IC control,with -V intelligent cut off the rapid charging function,automatic transfer to trickle-charging,insure ssafety usage. The LED will be on and show its background for 2 seconds afterconnected with the power source,then off. There is letter "CHG" showing on LCD after battery loaded. The word "ERROR" which means defective or non-rechargeable battery loaded would be shown on the corresponding posititon on the LCD if such kind of battery loaded.And the coressponding battery photo would flash. Over-discharge protect,constand current charging can keep battery life,and insure safety usage. Over-temperature protect:(>60 centigrade use) the battery and charger temperature is too high and it will auto-cut off charging, insure safety usage. Auto-identify function, indicate the non-rechargeable battery,short-circuit battery,defective battery,then the charger will not charge to protect using safety. Refreshing battrey function:if the battery voltage getting less(0-0.9V),charger can refresh the batttery. Short-circuit protection: avoid the battery polarity "+/-" short-circuit protect. Worldwide Voltage,Sutiable for the whole world.