Battery management system (BMS) is an intelligent component that plays a significant role in maintaining the safety, performance, charge rates and longevity of a battery pack.
The BMS monitors the cells within a battery pack and calculates an appropriate amount of current that can flow into each cell when charging or discharging a lithium-ion battery.
Safety
Safety should always be a top priority when designing battery management systems. Lithium-ion batteries contain flammable liquid electrolyte, so they must operate within specific limits at all times to avoid fire or explosion hazards.
One of the most essential safety components in a battery management system is thermal runaway protection. This safeguard helps avoid an emergency where cells start venting flammable gases when they reach an unsafe temperature, potentially endangering those around them as well as property.
Another essential feature of a battery management system is its capacity to detect and avoid short circuits, particularly with large format lithium-ion batteries. Furthermore, this protection helps safeguard the battery against overvoltage, extreme temperatures, and other problems which could damage or even explode it.
Battery management systems monitor the current, voltage, and temperature of each cell in a battery pack. These readings enable them to determine when it is safe to charge or discharge the battery.
A Battery Management System (BMS) can also protect the battery by maintaining equilibrium within its cells to avoid them drifting apart from one another. This ensures the battery operates optimally and lasts longer.
When a battery pack is in use, it can be exposed to various conditions like vibrations, extreme temperatures and dirt. These elements can cause the battery to breakdown prematurely – potentially dangerous for anyone around it.
The battery management system must also be able to identify when a short has occurred, in order to halt charging or discharging activities. This is especially pertinent for large-scale batteries situated in potentially hazardous environments.
It is essential to be aware that lithium-ion batteries can become damaged if exposed to freezing temperatures. This condition damages their metal anode and reduces their capacity.
That is why it is imperative to design a battery management system that ensures the safety of those using the battery. This is the only way to guarantee your batteries are always operating safely and optimally.
Monitoring
Battery management systems are essential components for electric vehicles, as they keep the battery secure, extend its lifespan, and provide accurate information about its status. These systems closely monitor and communicate with the onboard charger to guarantee that batteries do not receive excessive charge or discharge.
The Battery Management System (BMS) collects information about a battery’s voltage, current, and temperature. This data can then be utilized for optimal charging and discharging operations.
Voltage and Current Limits: Lithium-ion cells have a relatively narrow voltage range, spanning from -4 degrees Fahrenheit (20 degrees Celsius) to 131 degrees Fahrenheit (55 degrees Celsius). If the voltage drops too low or rises too quickly, it can damage the cell.
Temperature: The temperature range of lithium-ion cells is critical for safety, as thermal runaway can occur if the pack runs too warm or cold. To prevent this from occurring, the battery management system (BMS) monitors both battery pack and cell temperatures and adjusts heating or cooling fans as necessary to maintain ideal conditions.
Capacity: Battery capacity can fluctuate due to self-discharge, charge/discharge cycling and temperature effects – all of which can reduce its life span. The BMS compensates for these variations with cell balancing, which equalizes SoCs across adjacent cells in a pack assembly.
Integrations: The battery management system can be seamlessly integrated with a variety of devices and software packages, providing users with insights into their operations while avoiding costly disruptions.
A reliable monitoring system should enable users to set alerts based on specific criteria, such as time or location. Furthermore, it offers a dashboard that presents data clearly and concisely.
Integrating a monitoring system with other applications and systems can enable users to quickly respond to emerging situations. Furthermore, this saves them time and money by allowing them to leverage existing solutions.
A reliable monitoring system will continuously assess the performance of its components and report on their status to help engineers decide what improvements need to be made to enhance efficiency or enhance performance. It also offers easy access to essential information for troubleshooting and maintenance, enabling users to address problems before they become major issues.
Communication
Battery management systems monitor and regulate the charging and discharging of batteries. They detect the type, voltages, temperature, capacity, state of charge, power consumption and other characteristics of a given battery.
In addition, they can detect the health of each cell and pinpoint the cause of malfunctions. Furthermore, they have the capability to stop power flow and sound an alarm if necessary.
One of the key functions of a BMS is monitoring cell temperatures. If temperatures rise too high, the system can activate thermal runaway safety mechanisms to halt operations and minimize risk.
Another essential feature of a battery management system is its capacity to convey information about battery condition and status to users or other equipment. Typically, this involves sending data from the battery via communication bus to displays or other devices.
Battery management systems can either be centralized or distributed (Figure 6). With a centralized BMS, there is one main control board located within the battery pack assembly that links all batteries directly.
This topology has several advantages, such as compactness and cost efficiency; however, it can also present complexity and difficulty when troubleshooting or extending the BMS to larger battery packs. Furthermore, there are a lot of wires, cabling, and connectors involved.
The distributed BMS is a more versatile design, capable of accommodating higher voltage and current demands in battery packs that need it. Furthermore, it reduces bulk while simplifying cabling requirements.
A distributed BMS utilizes a daisy chain ring topology in addition to its main control board, where each monitored cell has its own sensor module connected to a slave printed circuit board which polls the master for updates. An RS 485 three wire data bus links these sensors together at the master board level.
No matter the BMS topology selected, its primary role is to optimize battery performance through regenerative braking and energy storage. To do this, it’s necessary to understand each cell’s state-of-charge (SOC). This can be accomplished by redirecting excess current around high SOC cells during charging cycles so all other cells reach their maximum SOC without overcharging.
Control
A Battery Management System (BMS) monitors a battery to guarantee its safety and efficiency. It collects information from sensors within the battery and processes it for protection against overcharging, extreme temperatures or other hazards. Afterwards, the BMS provides this data to its user.
Batteries operate most efficiently when exposed to certain conditions, such as voltage, temperature and current. Overcharging or operating the battery outside these ideal conditions can significantly shorten its productive life and create potentially hazardous situations like explosion or fire.
All batteries have voltage and temperature limits that are designed to protect them from damage. These limits, known as shutdown thresholds, may be set by either the cell manufacturer or car manufacturer depending on what needs are met by the vehicle.
The BMS regulates charging by instructing the charger to reduce or cease current when the battery approaches its limits for either voltage or temperature. This safety feature shields both drivers and batteries from permanent harm.
It can also disconnect a battery from its load circuit if charge or discharge conditions become hazardous for either the battery or charger. This is done using an electrically controlled switch, commonly referred to as a field-effect transistor (FET).
Two types of BMSs exist: centralized and distributed. Centralized type BMSs use a single control unit that oversees all monitoring modules. While designing and building a centralized BMS is simpler and cheaper, its main disadvantage is that if one of its control units malfunctions, all other monitoring modules will too.
Distributed BMSs are typically composed of submodules, each with its own dedicated bundle of wires and connections to an adjacent portion of a battery stack. This makes troubleshooting and maintenance much simpler, while also enabling extensions to larger batteries without adding extra control units.
A battery management system is an integral component of any electric or hybrid vehicle that uses a rechargeable lithium-ion battery. A well-designed management system can make all the difference between long lasting batteries and those needing replacement frequently.