The invention provides a device and system for replacing storage batteries and relates to the field of transportation facilities. The system comprises a cabinet, a storage battery device, an electric quantity detection unit, a charging unit and a billing unit; the storage battery device is installed inside the cabinet; the electric quantity detection unit is used for detecting the electric quantity value of the storage battery; the charging unit is used for charging the storage battery; the billing unit is used for calculating cost. By means of the device and system of the invention, the technical problem of limiting charging mileage of battery cars since the electric energy of a battery is used up and therefore limiting the operation mileage in the prior art is solved.