What is a Battery Management System (BMS)? The Brain Behind Lithium-Ion Batteries

The Human Analogy: How BMS Brings Batteries to Life

Imagine walking into your favorite bakery. Your eyes scan the variety of treats in the glassed casing. Your ears pick up the humming and whirring of the ovens. Your skin senses the warmth in the room. Your nose picks up the smells of freshly baked bread coming out of the oven. Your tongue might tell you if the coffee you got with your treat is too hot. All these inputs you get from your senses are sent to your brain, which processes them and decides how to respond.
Now imagine a lithium-ion battery (LIB) as a living system. To keep itself safe, functional, and long-lasting, it depends on a combination of hardware, like sensors and wiring (its nerves), and software that processes information and makes decisions (its brain). This intelligent system is known as the Battery Management System (BMS)
LIBs are used in a wide range of applications—from consumer electronics to electric vehicles (EVs). They are favored over other rechargeable chemistries, such as Nickel Cadmium or Lead-acid, due to their high energy density, long cycle life, and low self-discharge rates. However, to ensure safety and longevity, LIBs must operate within strict voltage and temperature limits, as shown in Figure 1.

Figure 1: Operational window of a lithium-ion battery

This is where the BMS comes in. Like a central nervous system, the BMS combines hardware and software to collect information from its “sensory organs” (sensors) and make real-time decisions to ensure safety and optimize performance. The complexity of a BMS depends on the application. Devices like e-readers or smartphones may use simpler architectures, while large-scale electrified systems – such as marine propulsion platforms, electric vertical take-off and landing (eVTOL) aircrafts, or electric vehicles (EVs) – require more advanced systems with additional sensors, advanced algorithms, and robust safety considerations.

The BMS Itself

Just as our senses feed information to our brain for interpretation and decision-making, all measurable inputs from a battery pack ultimately report back to the BMS—the brain of the operation. The BMS doesn’t just collect data; it continuously evaluates the health and performance of the battery and makes real-time decisions to ensure safety, efficiency, and longevity.

Figure 2: Conceptual illustration of a Battery Management System

From estimating internal states like State of Charge (SOC), State of Health (SOH), and State of Power (SOP), to making protection decisions and issuing control commands, the BMS is responsible for orchestrating every aspect of battery behavior. It must process noisy signals, respond to sudden changes, and adapt to variations across cells, modules, and operating conditions—all while meeting tight constraints on size, cost, power consumption, and timing.
In the following blog, we will take a deeper dive into the underlying BMS architecture and all the different components that are involved.

What’s Next in Our BMS Journey

This blog marks the beginning of our educational series on Battery Management Systems (BMS). Throughout the series, we’ll explore what a BMS is, its architecture and applications, and how simulation supports its design, testing, and validation including XiL (Model-, Software-, and Hardware-in-the-Loop) approaches. We’ll also share real-world case studies demonstrating how BMS solutions are shaping electrified mobility and beyond.
🎬 Check out our BMS playlist on YouTube for quick insights and visual explainers.
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