The Critical Role of Battery Management Systems (BMS)

In modern energy storage solutions, Battery Management Systems (BMS) are indispensable for ensuring optimal battery performance and safety. As the “brains” of battery operations, BMS units are crucial for both maintaining reliable and safe functionality as well as maximizing battery life. This is particularly vital in applications ranging from electric vehicles (EVs) to renewable energy storage and portable electronics.

The Dual Functions of BMS: Safety and Performance

BMS’s operate on two primary fronts: safety and performance. On the safety side, a BMS monitors various parameters such as voltage, current, and temperature. This monitoring is essential to prevent hazardous conditions like overcharging, over-discharging, overheating, and short circuits. For example, in EVs, a BMS ensures that the battery does not overheat during rapid charging or sustained discharge, which could lead to thermal runaway—a potentially catastrophic event.

On the performance side, a BMS manages the state of charge (SoC) and state of health (SoH) of the battery. By accurately estimating these states, the BMS can optimize charging and discharging cycles to prolong battery lifespan and improve efficiency. This function is critical in maximizing the range of EVs and the longevity of batteries in renewable energy systems, where frequent cycling is common.

Interdisciplinary Approach: Software and Electrical Engineering

The development and optimization of BMS units requires a confluence of software and electrical engineering. Electrical engineering focuses on designing the hardware components, such as sensors and circuitry, that monitor battery conditions and ensure safe operation. This includes the creation of robust power management circuits and integrating them seamlessly with the operations of the battery pack.

Software engineering is pivotal in developing and implementing the algorithms that process data from the sensors, predict battery behavior, and make real-time decisions. These algorithms must be sophisticated enough to handle the complex electrochemical nature of batteries and the various environmental conditions they may encounter. The software also plays a role in communication with other systems, such as vehicle control units in EVs or grid management systems in renewable energy applications.

Challenges in Optimizing BMS

Optimizing BMS involves addressing several challenges.

• • One major challenge is achieving accurate state estimation. Due to the non-linear voltage response of battery chemistry in operation, predicting SoC and SoH can be difficult and imprecise, especially at extreme temperatures.  This requires large data sets developed from cell bench testing, coupled with advanced modeling and machine learning techniques.

• • Another challenge is managing the trade-off between safety and performance. Ensuring the battery operates within safe limits can sometimes limit its performance, necessitating a delicate balance.

• • Balancing features with cost represents another tradeoff.  Knowing when to choose between passive and active balancing is critical in hitting performance and cost targets. Ironically, batteries for consumer products stand to benefit the most from intelligent battery management and safety protection, but cost sensitivities often dictate that a simpler system be applied to these batteries.  Skilled engineers can minimize the impact of de-featuring a BMS.

• • For large battery systems, BMS architecture choices such as centralized, distributed or hybrid systems are a balance between complexity, cost, and benefits. These choices have a substantial impact on developing the BMS for a specific battery architecture.

• • Communication protocols have expanded over the years and many systems now take advantage of multiple protocols, but this can further add to the complexity of a BMS unit’s electrical and software interactions.

• • High Voltage systems as seen in EV’s require more functional safety and BMS involvement with features like High Voltage Interlock Loop (HVIL), isolation monitoring, and contactor functional checks.

• • Moreover, BMS must be designed to handle a wide range of operating conditions and a breadth of battery chemistries. This requires extensive testing and validation, which can be time-consuming and costly. As battery technologies evolve, BMS must continuously adapt, incorporating new algorithms and hardware to accommodate these advancements.

 

In conclusion, BMS units are vital for the safe and efficient operation of modern batteries. The interdisciplinary nature of their development and the challenges involved in their optimization highlight the complexity and importance of this technology in the rapidly advancing field of energy storage.

About Treetown Tech

Treetown Tech provides deep knowledge and execution in cell chemistries, cell products, battery pack design, development, prototyping, production, and battery management systems (BMS). Our battery expertise and services are complemented by Treetown Tech’s extensive product development and engineering capabilities including software, electronics, and mechanical system design, located in a state-of-the-art facility in Ann Arbor, Michigan. You can learn more about our battery engineering solutions here and the rest of our capabilities here.