Low self discharge,  batteries already charged & ready to use. can be recharged over and over again up to 2,100 times. can be used at temperatures down to -20ºc. **batteries made in japan. battery protection. safe. alkaline batteries detector. charging terminate when detects alkaline batteries(disposable batteries). world auto voltage. charger time 6 hours. the fujitsu standard charger is more flexible and prevents batteries from over-charging. charging stops each battery when is full. plug in the charger before going to bed and batteries are fully charged when you wake up in the morning. battery protection - charger can detect alkaline batteries and wrong positioning.when detected, charging will be terminated. 8 hour timer shut off ensures batteries are not over-charged. world auto voltage - automatically calibrates to the voltage where you are.