Small and lightweight, the Sony NP-FD1 D-Series Info-Lithium Battery can be charged or discharged at anytime without developing memory effect. This means it will never lose the ability to hold a full charge. it also provids info to the camera to display remaining battery time on the LCD and/or viewfinder by continuously communicating with the camcorder because the D-Series Info-Lithium battery packs have a built-in micro processor that accurately calculates remaining battery life in minutes.