48V 13Ah Silverfish Electric Bicycle 2-pins E-bike Battery for 350W 500W 750W. (the middle is empty). It is not 4 pins. Size is 39117.5cm. Please confirm it is for your bike. If you don’t know, please send message to me to confirm. The discharging positive (-) is on the key and charging socket side. Please make sure the polarity. 1 x Lithium Battery. 1 x charging cord. 1 x User Manual. 1 x Battery Fixed Plate. Fit for 48v E-bike and your motor should be 48v 350W-750W. Battery Type:Fish Lithium-ion. Rated Voltage / capacity: 48V / 13Ah. W: 3.26KG/3.66KG. Battery Size:(mm):L390W110H75 (inch):L15.4W4.35H2.95. Case Material: ABS+Aluminium alloy. Batteries combinations:13-S, 5-P. Component:Li(NiCoMn)O2. Recommend to use: 250W-750W Motor. Cycle life:1000 times. Charging:0°C45°C Discharging:-20°C60°C Storage:0°C30°C. PCB board Protection:Over charge, over discharge, over load and short circuit. BMS board Protection:BMS is used to supervise battery by measure its voltage, temperature, current and SOC (State Of Charge), give out alarm under wrong circumstance, cut off electric power link in severe situation in order to protect battery and make its life longer. BMS can balance energy among batteries to make them more identical and expand its discharge cycle.