The Future of Electric Vehicles: A Sound Battery Management System

By Supratim Naskar, CoFounder and CTO, Cell Propulsion

The electric mobility industry in India is at a seemingly critical juncture given how the electric vehicle (EV) ecosystem is rapidly developing in India and abroad. From a policy perspective, it remains vital that government interventions and initiatives at this stage lay down the foundations of a domestic EV industry, touted to be the industry of the future for the automobile sector. The EVs fulfill two-pronged objectives for the country. Primarily, they create the necessary disruption in the auto sector that brings down India’s import dependency on petroleum and natural gas. They also contribute immensely to bringing down the auto-related green-house gas emissions, and broadly to India’s Paris Climate commitments of reducing the emission intensity of its gross domestic product by 33% – 35% by 2030.

Efficient EV value chains remain dependent on the efficiency and pricing of the inputs. To this end, the battery technology in the EV segment has received a lot of attention, given how batteries form the backbone of EVs. Li-ion battery packs are in high demand in the automotive industry as power sources for electric, hybrid, and plug-in hybrid vehicles. These batteries have a high charging capacity and a long lifespan due to its ability to store significant amounts of energy and be recharged multiple times. However, lithium-ion batteries can only be utilised under certain conditions, a battery management system (BMS) is required to monitor battery state and maintain operational safety.

The Importance of Battery Management System (BMS)
Given how vehicles of all kinds are subjected to random vibration, shock loads, water immersion, and thermal loads, among other harsh operating conditions. Sophisticated BMS is much needed for the battery packs.

The designing and functioning of such systems involve extensive research pertaining to several aspects of battery management. Processes like battery modelling allow to both predict and simultaneously optimize battery’s parameters including its charging and discharging time-periods, State of Charge (SoC), and the lifetime of the batteries. Exact estimate of charge and health of battery packs is made easier with accurate battery models. Cell balancing processes are also used extensively to deal with voltage imbalance that can reduce the performance of battery packs. Based on these key pillars, BMS are being designed as intelligent control systems that work to enhance the efficiency and lifetime of the EV batteries, and that of the vehicle. These remain the future of EV technologies and key to an effective and sustainable EV ecosystem in India.

What Makes a Sound BMS?
BMS are designed to perform several important functions for an EV battery, ranging from basic monitoring and protection of the battery cells to State of Charge and State of Health estimation of batteries. The BMS systems also perform certain other high end functions including intelligence gathering about the system, acquisition, and storage of data regarding critical battery parameters such as cell voltage, battery charge/discharge current, cell, and battery housing temperatures, among others. The data points that are acquired and processed, help in state estimation of the battery packs such as State of Charge (SoC), State of Health (SoH), and State of Power (SoP).

We must remain cognizant of the fact that the BMS are a safety critical system, and any failure can cause catastrophic failures of the battery systems. Keeping this in mind the BMS are being enabled with self-checks during initialization of the system. Some of these critical checks include peripheral checks, memory checks, check for any fault in the system like Over voltage, Under Voltage, Short Circuit, Over Temperature, System memory check, System humidity and Insulation levels.

The Road Ahead for Battery Advancement and BMS
As the designs of EVs evolve, the design of batteries and subsequently the role of battery management systems will also evolve simultaneously in order to ensure operational efficiency, affordability, and longevity of the battery systems in particular, and EVs as a whole. With every new EV in the market the BMS evolves to get much smarter and easy to use. Currently we are in the advent of the age of Electric Vehicle in India, and it is expected to become more important in near future. Smart Batteries and allied solutions will empower the Electric Mobility sector in India.