This document describes the design and implementation of an IoT-based smart battery management system (BMS) for an e-bike application. The system measures the voltage, current, and temperature of each cell in a 3-cell lithium-ion battery pack. An Arduino microcontroller sends this data via a BOLT IoT module to a cloud server for analysis. The cloud analytics can detect faulty cells and notify the user. The BMS also performs passive cell balancing to efficiently and safely charge the battery pack over long periods. Hardware and software designs are presented, along with simulation and testing results demonstrating monitoring of battery parameters and cloud-based fault detection.