Roman Bykadorov of Lemberg Solutions writes that active cell balancing can help mitigate battery management and lifecycle issues, but its application requires complex consideration.
Improving battery efficiency offers multiple opportunities for your business, including cost savings, growing customer satisfaction, and increased sales margins. Active cell balancing is an optimal solution to achieve these goals, as it is the key to reducing battery heating and improving energy use efficiency.
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With active cell balancing, energy is evenly distributed among the cells rather than being converted into heat. It also allocates higher current levels as the energy is redistributed efficiently. This article will aim to present the benefits of active cell balancing and technical approaches that will help you introduce it to your battery management system (BMS).
Why active cell balancing?
Even if the battery cells are well-matched by the manufacturer, some cells begin to store less charge and degrade faster than others over time. It depends on individual cell properties as well as the physical location of the cell, e.g., different pressures and temperatures will promote capacity variation. Besides, slight manufacturing differences are a valid consideration, as cell variation will increase with time. Whatever the reason behind growing cell variations, eventually, cells become unbalanced — they charge and discharge inconsistently.
This leads to waste of energy, early battery degradation, and safety issues.
At this point, active cell balancing comes into play. It helps prevent all of the above risks by transferring energy from stronger to weaker cells, improving overall battery performance.
Let’s take a closer look at the benefits:
Higher energy efficiency
Energy transfer-based cell balancing is more efficient for battery systems. By redistributing energy from stronger to weaker cells, you’ll get the opportunity to preserve more charge and make your system’s consumption more efficient. This is especially beneficial for large-scale systems, such as electric vehicles (EVs) or large-scale battery energy storage for grid regulation, load shifting, or renewable energy integration.
Extended battery life
Active cell balancing improves battery capacity and health by reducing cell stress caused by overcharging and discharging. Consistent cell balancing leads to slower battery degradation, prolonging its lifespan.
Fast charge balancing
Active balancing provides a much faster energy transfer among cells, improving scalability and cell balancing speed. Rapid balancing is crucial for systems with a large number of cells.
Lower heat generation
While passive balancing methods convert excessive energy into heat, active balancing ensures that the energy is transferred rather than dissipated. That’s why active balancing systems are perfect for compact or heat-sensitive devices, and are critically important for large-capacity storage.
Improved safety and reliability
Active cell balancing keeps voltage within safe bounds, reducing the chances of cell over- and undervoltage. Ensuring equal energy distribution is especially critical for applications with strict safety requirements, like grid storage or aerospace industry projects.
Introducing active cell balancing
To achieve tangible results, you’ll have to get to the core of the underlying pitfalls. Design is the main challenge while engineering an active cell balancing system. Unlike passive cell balancing, active cell balancing requires a more complex design.
While a passive balancing system consists of a transistor and a resistor, an active balancing system requires a coil to redirect energy between the different cells. With the energy stored in inductors, the active balancing system also consists of a transistor and driver microchip. The energy stored in the inductor is transferred to a specific cell, requiring a more complex controller to determine the energy destination and forward it to the defined cell.
Manufacturers provide ready-to-go reference designs for the DC-DC controllers that can be tailored to your specific needs for active cell balancing. Another option is open-source investigating results available for further customisation to your cell-balancing needs.
Let’s review potential ways for introducing active cell balancing below.
Off-the-shelf ICs and reference designs
The most straightforward method is to use ICs and reference designs provided by manufacturers. Monolithic Power Systems delivers ready-to-go reference designs, helping embedded engineers integrate active balancing quickly and efficiently. Off-the-shelf solutions usually include circuit topologies such as flyback or Cuk, basic firmware, and built-in communication protocols.
Thus, using reference designs is an optimal option for commercial products or rapid prototyping.
Custom circuit design based on converter topologies
Engineers can design circuits from scratch to build a tailored solution using converter topologies like flyback or Cuk. This approach allows you to customise all cell balancing parameters, including battery efficiency, heat dissipation, and PCB layout. However, if your deadlines are tight or your engineers don’t have the necessary experience, this may not be the best option for you.
There’s no one-size-fits-all solution
After reviewing ways to implement active balancing into a BMS, it becomes clear that there’s no ‘one-size-fits-all solution’ for all applications—your choice will depend on your specific needs and requirements.
Many off-the-shelf solutions leave little room for customisation. Thus, if high adaptability and long-term optimisation are your priorities, open-source and custom-designed solutions are better for you. However, if your deadlines are tight or your engineering capacity is insufficient, ready-to-go solutions might be your best choice.
At Lemberg Solutions, we’ve been helping businesses introduce active cell balancing to their battery management systems. Behind each successful implementation stands a detailed analysis of the desired cell balancing logic and business goals. Thus, before integrating active cell balancing into your system, make sure to analyse your needs and BMS specifics first.
About the Author
Roman Bykadorov is the embedded engineer tech lead at Lemberg Solutions, a tech consulting & software engineering company. Roman specialises in both software and hardware, developing a wide range of system solutions for embedded electronics. Successfully delivered projects across diverse industries, including heavy machinery, industrial electronics, Industrial IoT, automotive ECU development, as well as smart home technologies and consumer electronics.
