Understand the BMS Components and Functions

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Electric vehicles, Renewable energy storage, Smartphones… Battery technology powers some of the most influential innovations of our modern world. And what makes batteries more effective, reliable, and safe? It is a Battery management system (BMS). In this blog, we’ll briefly introduce what battery management systems are, and explore the BMS components, and how they work to get the best performance from battery packs. Read on to learn about this key enabling technology!

What is a Battery Management System?

A battery management system, or BMS, is an electronic monitoring and control system that manages rechargeable battery packs found in electric vehicles, renewable power stations, uninterruptible power supplies, and other advanced applications requiring efficient battery operation.

The purpose of a BMS is to optimize battery pack performance, longevity, and safety. To achieve this, it carries out several key functions:

  • Charging and discharging control – Regulates the battery’s charge and discharge currents and voltages to prevent damage. This helps maximize capacity utilization.
  • Cell monitoring Tracks parameters like voltages and temperatures at the cell level to detect issues early.
  • Balancing Ensures the individual cells in a pack stay in the same state of charge and health through redistribution of energy. This maintains pack stability.
  • Thermal management Holds cell temperatures within safe operating ranges through cooling or heating as needed. This preserves battery life.
  • Reporting and communication Provides status data to other systems and allows control instructions via interfaces like CAN bus.

In short, BMS technology gives battery packs “brains” to self-manage for efficiency, longevity, and protection.

Main Components of a Battery Management System

Now let’s look under the hood to understand the principle BMS components and what they contribute:


The microcontroller acts as the central brain, orchestrating all operations. It continuously acquires data from various sensors, processes this information using complex algorithms, and makes critical decisions. The microcontroller manages tasks such as cell balancing, thermal regulation, fault detection, and communication with external devices. Popular choices for microcontrollers in BMS designs include ARM Cortex M4 processors, known for their high performance, low power consumption, and extensive peripheral support.


Sensors play a vital role in providing the microcontroller with real-time data about the status of individual cells within the battery pack. To monitor the status of each cell in the battery pack, the BMS employs several types of sensors:

  • Voltage sensors: These sensors measure the voltage across each cell in the battery pack, providing critical data to the microcontroller. This information is essential for monitoring the state of charge (SOC) and preventing overcharging or excessive discharge of individual cells, both of which can lead to degradation or safety issues.
  • Current sensors: By monitoring the current flowing into and out of the battery pack, current sensors enable the BMS to control charge and discharge rates, detect anomalies in current flow, and optimize runtime. Common current sensor technologies include Hall effect sensors and shunt resistors.
  • Temperature sensors: Temperature sensors are strategically placed throughout the battery pack to monitor the temperature of individual cells or groups of cells. This allows the BMS to detect hotspots that may arise due to internal flaws, excessive load conditions, or other issues. Temperature data is used to predict potential faults and trigger appropriate thermal management actions to regulate cell temperatures within safe operating ranges, thereby preserving battery life.

Cell balancers

Cell balancers are crucial components that help maintain an equal SOC across all cells in the battery pack. As cells age or undergo different charge/discharge cycles, they can develop imbalances in their SOC. Cell balancers employ techniques such as shunt resistors or transformer-based circuits to redistribute energy from stronger cells to weaker ones during periods of inactivity or low load. This balancing process improves the overall stability and lifespan of the battery pack by preventing individual cells from becoming overcharged or excessively discharged.

Power switches / Relays

Power switches or relays act as safety breakers, providing a means to electrically isolate the battery pack from energy flows in the event of faults, overheating, or other critical issues. These components are typically implemented using low-on-resistance (RDSON) field-effect transistors (FETs) or solid-state relays, which can rapidly disconnect the battery from the load or charging source to prevent further damage.

Thermal management system

The thermal management system is responsible for regulating the temperature of the battery pack within safe operating limits. It consists of dedicated components such as cooling fans, heating pads, liquid cooling loops, or phase change materials. The specific approach depends on factors like the battery chemistry, pack size, and application requirements. The thermal management system works in concert with the microcontroller and temperature sensors to actively monitor and control the temperature of individual cells or cell groups, ensuring optimal performance and longevity.

Communication interfaces

Modern BMS designs incorporate communication interfaces that enable the exchange of data and control instructions with external systems. Common protocols used for this purpose include the CAN bus, Universal Asynchronous Receiver-Transmitter (UART), and others. These interfaces facilitate communication with charging stations, battery optimizers, cloud monitoring platforms, or other connected devices. This connectivity is essential for the BMS to perform functions such as receiving charge/discharge commands, reporting diagnostic information, and enabling remote monitoring and control.

These key BMS components form an integrated system that actively monitors cells, balances charges, optimizes flows and coordinates cooling – all to enhance battery performance, longevity, and safety.

Optimizing Battery Life and Safety

A well-designed battery management system can significantly enhance critical aspects of battery operation through its active monitoring and control capabilities:

  • Performance optimization – By continuously tracking cell voltages, currents, and temperatures, the BMS can orchestrate precise charge/discharge control. This enables squeezing the maximum available capacity out of the battery pack without exceeding safe operating limits.
  • Lifetime extension – The BMS works to prevent cell damage from abuse conditions like overcharging, excessive discharge currents, and extreme hot or cold temperatures. Catching issues early avoids permanent capacity degradation.
  • Safety assurance – Keeping all cells balanced at similar states of charge is key to the BMS’s role. It employs cell balancing algorithms and redistributes energy from stronger to weaker cells to maintain consistent pack health. This prevents dangerous imbalances from developing.

In essence, an intelligent BMS acts as the brain governing battery packs. Through careful regulation based on real-time data and modeling, it prevents conditions that would otherwise lead to failures, fires, or early end of life. The result is safer, higher-performing batteries that provide reliable service over extended durations.

MOKOENERGY – Advancing BMS Technology

As a leading provider of battery management solutions, MOKOENERGY brings extensive expertise in intelligent BMS design, modeling, prototype building, and compliant mass production.

Through tailored solutions leveraging technologies like cell balancing, cloud connectivity, and model-based control, MOKOENERGY helps customers:

  • Obtain higher-performing, longer-lasting battery packs for a competitive edge
  • Meet emerging application challenges in areas like electric mobility
  • Speed up product development cycles through custom BMS development
  • Reduce BMS costs through optimized designs

Overall, we enable organizations to get quality BMS faster and maximize return on investment.

The Future with Smarter Battery Management

The growing impact of battery technology across diverse applications like electric vehicles, renewable energy storage, aerospace, and consumer electronics is driving battery management systems to become increasingly intelligent and tightly integrated. With rapidly expanding markets, motivations to optimize and innovate BMS solutions are intensifying. We can expect advanced BMS with capabilities like machine learning for sophisticated monitoring and control, cloud connectivity for remote analytics, modular scalable designs, and precision simulation modeling. Leading companies like MOKOENERGY will remain at the forefront, advancing state-of-the-art intelligent energy storage solutions. Through smarter battery management, the future promises safer, higher-performing, longer-lasting battery packs to enable innovations that reduce environmental impact and improve quality of life.

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