4 independent ports can be used at the same time. 4 different types of battery connections in each port. 4 independent charge circuits. 4 independent 4-digital LED displays power and capacity. LED and audible charging status display. Adjustable charging current of 0.1-1.5A. AC / DC dual-power input. Efficient ventilation. Maximum protection: short circuit protection; over current protections; Battery reverse polarity protection and DC input voltage protection.