Charges 7.2V 8.4V or 9.6V Ni Cd & Ni MH rechargeable 9V PP3 batteries Charges 1-4 9V batteries simultaneously Independent charge channel for each battery Reverse polarity protection for each channel 2-3 hours average charge time Overcharging prevented by 5 hour timer protection Temperature control prevents batteries form overcharging Short circuit protection LEDs indicate charging status or reverse polarity for each individual battery Automatically switches to trickle charge mode once the batteries are fully charged Worldwide voltage travel adaptor maybe required