Features:5. 5X2. 1mm 5. 5x2.. 5mm DC connector ; Special charger for 48V lithium battery pack. The charger Built-in simply fan, with radiating fin surrounding the board, dissipating the heat through the shell, so some hot on the shell when charging is very normal, but it is durable. The Charger protected: Short circuit protection ,over current protection, over voltage protection; Red light -- charging, green light -- charge OK, it stop automatically when the battery is full. Durable to Use: Made of High Quality Material, Durable to Use.