Overview
Batteries are complex. Some aspects of their performance and degradation even experts don’t completely understand. You could argue that testing a battery is closer to testing the human body than a circuit board. Like humans, batteries are dynamic, their condition changes due to their environment and usage, and each one behaves a little differently. Combine this ambiguity with the need to boost performance, reduce testing times, and scale production and we see that the industry must evolve quickly.
As the automotive industry goes through a massive transformation to electrify vehicles, batteries are front and center. Perhaps no component has ever had such a far-reaching impact on the final product while also undergoing its own rapid pace of technological changes.
Historical approaches to battery cell test do not all transfer seamlessly to new battery technologies, which can yield inaccurate results and inadequate insights. We must re-engineer and transform our processes using AI, ML, automation, and digital transformation to improve accuracy, optimize efficiency, and provide valuable insights.
Batteries present unique test coverage requirements. Automakers are accustomed to testing electromechanical systems, but batteries also comprise chemistry. This additional variable introduces an additional layer of complexity that requires not only electrical and mechanical testing procedures but also necessitates understanding and monitoring the electrochemical processes integral to a battery’s operation and performance.
Battery Production Overview
It’s difficult to discuss battery cell testing without understanding the production process. Battery cell production requires many steps using different technologies and domains, such as chemical compound mixing, mechanical assembly, material lamination, welding, and more. Each step has a profound impact on the quality of the final battery. To summarize, the production process is grouped into a few macro areas: electrode manufacturing, cell assembly, the conditioning phase, and pack assembly.
Electrode Manufacturing
Electrode manufacturing is where the fundamental components of a battery are made from raw materials. This process starts with mixing a slurry, applying the slurry to metal foils, and cutting the coated foils for further stages. These coated foils become the anodes and cathodes, which are the electrodes of the battery.
A mix of active materials, solvents, and a binder make up the slurry that is used in the electrodes for storing charges. The formula for the slurry depends on the chemistry of the cell and the type of electrode (anode or cathode). The slurry mix sets the stage for the performance of a battery cell. The slurry is applied to metal foils through a precise coating process. The coating must then dry so the solvents can evaporate, leaving only the active material on the foil. The dimensions of the foils influence the cell’s architecture and form factor.
Multiple variables are monitored and controlled during the coating and drying processes. Slurry viscosity, coating speed, and foil tension impact the thickness and uniformity of the coating. Temperature and humidity must be strictly regulated during the drying process. The dried foils are passed and compressed between rollers in the calendaring process. Calendaring improves uniformity, reduces the overall electrode thickness, and smooths out imperfections. The electrode sheets are then precut into manageable shapes for cell assembly.
Cell Assembly
Battery cell assembly is performed in a rigorously controlled environment to avoid degradation of the electrodes from moisture, dust particles, thermal expansion and compression on the materials. The electrodes are assembled in a battery cell through a process of cutting, stacking, packing, and sealing.
- The electrodes are cut into appropriate shapes, depending on the final cell form factor, such as cylindrical, pouch, prismatic, and so on.
- The anode electrodes and cathode electrodes are stacked with a separator between them. Different techniques are used in this process depending on the architecture of the cell. In all cases, the alignment of the layers is crucial to ensure there is no contact between the anode and cathode because any contact would lead to a short circuit.
- Thin strips of conductive metal called tabs are welded to the anode and the cathode. These tabs connect the electrodes to the external circuit.
- The cell is assembled in a preformed packing material, depending on the form factor.
- The packed cells are filled with an electrolyte that facilitates the movement of lithium ions between the anode and cathode during charging and discharging. Absolute precision is required in the filling process. Errors or contamination could degrade the battery’s performance or even pose safety risks.
- The filled cells rest for a period of time, called soaking. The soaking process allows the electrolytes to fully saturate the electrode materials and ensures no air bubbles are trapped in the cell.
- The battery cell is sealed to prevent the electrolyte from leaking and to keep air and moisture from getting in.
Conditioning Phase
At this stage, the battery cell looks like a battery, but it isn’t active. The cell is activated through a process called formation, which enables the cell to store and release electrical energy.
During formation, the battery cell undergoes a charge and discharge cycle. During charging, the electrolyte reacts with the electrode materials, and lithium ions move from the cathode to the anode, forming the SEI (solid electrolyte interphase) layer. The SEI layer prevents the decomposition of the electrolyte while still allowing lithium ions to pass through. After each formation cycle, the battery cell goes through a process of removing unwanted gasses generated by chemical reactions within the cell. The cell is then left to age and stabilize in a controlled environment before undergoing another formation process.
These processes and cycles vary greatly for each cell manufacturer and are repeated with different techniques. This entire phase is crucial for proper operation and longevity of the battery cell. The challenge is that it takes days; and traditionally, you won’t know whether you have a good SEI layer until this process is finished.
Battery Pack Assembly
Battery pack assembly comprises the process of assembling individual battery cells into a complete battery pack. Battery cells must be sorted, modules are assembled and interconnected, and a battery management system (BMS) is installed before being placed in the final enclosure. The BMS is a critical component that monitors and controls the battery pack’s performance. It keeps track of parameters like voltage, current, temperature, and state of charge. It can also adjust as necessary to maintain optimal performance and safety.
Figure 1: Battery Modules
- The cells are sorted based on their capacities and internal resistances. For optimal performance and lifespan, the cells within a battery pack should have similar performance characteristics. Cells that vary too much could lead to imbalances when charging and discharging, degrading the pack’s performance over time.
- Cells are physically arranged into modules and connected in a combination of series and parallel circuits to achieve the desired voltage and capacity. Multiple modules may be connected by wire bonding or welding conductive strips or wires to the terminals of the cells or modules. The construction depends on the requirements of the device or vehicle where the battery pack will be used.
- The modules and BMS are placed into a casing or enclosure. The enclosure protects the components from physical damage, helps to manage heat, and provides electrical insulation.
Validation engineers use various tests to verify aspects of battery cell quality and performance. Each test has different objectives, advantages, and disadvantages.
Collaborative Engineering with Global Technology Partners
Building a reliable battery testing system involves more than selecting the right tools. It requires software, hardware, automation, and data analysis working together as one system. Haliatech partners with global leaders in test and measurement technology to ensure that every solution is robust, scalable, and aligned with industry standards.
This collaboration allows organizations to implement systems that support various stages, including:
- System design and simulation
- Prototype development
- Testing and validation
- Deployment and long-term support
Whether for research laboratories or production lines, the solution can grow alongside technology needs.
Why Battery Cell Testing Matters
A battery cell is a complex electrochemical system. Its behavior is influenced by manufacturing consistency, material composition, testing conditions, and how it is used over time. Even small variations during production can affect capacity, charging behavior, efficiency, and safety. Effective testing helps organizations:
- Detect defects early
- Improve consistency and traceability
- Reduce production waste and cost
- Accelerate development and manufacturing timelines
Modern testing also incorporates data analytics and automation to shorten testing cycles while maintaining accuracy.
Technology Used in Battery Cell Testing
Battery testing systems typically include measurement hardware and automation software to deliver accurate and repeatable test results. Common components include:
Related solutions are available through Haliatech’s product catalog:
National Instruments | Tektronix | Keithley | Elektro-Automatik
Pickering Interface | MacPanel
Figure 2 Battery Cell Validation Lab
Industry Reference and Best Practices
To support structured test development, Haliatech follows best practices used across global battery testing programs. One publicly available reference discussing battery cell testing methodology can be found here: Link
This reference provides an example of how modern testing frameworks can improve accuracy and workflow consistency in battery testing environments.
Conclusion
Haliatech helps organizations build scalable test systems supported by global technology partners and strong engineering capabilities. Whether developing new battery technology or scaling production, Haliatech provides the support needed from planning to deployment.
Free consultation available, contact us now!
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Email: sales@haliatech.com
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