Peoples have shifted from fossil fuel-powered vehicles to electric vehicles these days. It is environmentally friendly and also saves more energy. Electric scooter has two main components which are BLDC motor as a prime mover and battery as energy storage. Therefore, design of monitoring and diagnosing instruments are needed to maintain battery performance. Design of the instrument necessarily arranged to optimize the battery usage, monitor and identify an interruption or damage on battery used in electric scooter. Parameters used in design are voltage, current, temperature, and battery capacity. Furthermore, in optimizing the battery usage, all of the parameters are processed by a Controller Area Network (CAN) protocol. The parameters will be displayed on android smartphone to provide the scooter performance and give an alert if the interruption or damage is occurred such as over temperature and unbalanced cell. Based on the experiment results, it is shown that maximum error for current testing is 2.17% and for voltage testing is 0.09%. Maximum unbalance cell testing value reaches 12 % with an average value over 1 minute is 8.4% while safe limit of unbalance cell is 10%.