How to Overcome EV Battery Inspection Challenges

EV manufacturers are faced with unique EV battery inspection challenges, many of which are related to performance and safety. Therefore, manufacturers must implement inspection systems to safeguard against production issues affecting product quality.
In this resource, learn about common EV battery inspection challenges and how KEYENCE high precision measurement solutions solve them.

Understanding EV Battery Inspection

EV battery inspection is a process where the battery cells, modules, and packs are checked and tested for defects, electrical anomalies, structural deformities, and other deviations from established quality standards.

Different EV battery types are available and so are their unique EV battery inspection challenges. These issues typically arise due to battery design and production processes.

KEYENCE offers different battery inspection systems to handle many aspects of EV battery quality assurance efforts. KEYENCE laser displacement sensors can be used for coating, calendering, slitting, winding and lamination inspection in addition to assembly checks.

Inspecting battery cells, modules and packs for issues like potential overheating or structural imbalance helps prevent product hazards and unreliable performance.

Inspection Challenges for Different Types of EV Batteries

As previously mentioned, every EV battery type has unique inspection challenges, primarily due to build design and production routines. Common battery cells are pouch, prismatic, and cylindrical. Let's discuss common inspection challenges for these types of EV batteries.

Challenges With Inspecting Pouch Cells

Pouch cells lack rigid casing, which is one major reason for their higher energy density and lightweight design. Their casing — which is made from multilayer aluminum composite foil — makes them flexible. This creates lots of specular glare and wrinkles, making inspection difficult.

If an inspection system cannot accurately identify flaws on a pouch’s surface, it could lead to compromised battery integrity and performance. Such systems can also create false negatives where acceptable cosmetic blemishes are identified as critical surface flaws or defects.

The distinction between a flaw such as a scratch and any permissible imperfection like a blemish can be as small as a few microns.

Challenges With Inspecting Prismatic Cells

Lots of welding is involved in the manufacturing of prismatic EV battery cells. Prismatic cell sheets are housed in a rectangular metal casing. The casing or housing requires welding around the edges and a lid or top panel.

EV battery inspection challenges arise when checking for welding seams on the top and side panels before the cell is coupled into a module. Cold joints, spatter, burn-through, lack of fusion, and other types of underpowered and overpowered welds can be challenging to detect since weld seam defects come in different shapes and sizes.

Challenges With Inspecting Cylindrical Cells

Cylindrical batteries are metallic and round. Lot, date, material origin, and other DPM data are typically coded directly on the sides of the battery. Because these batteries are circular, codes are often deformed or distorted and traceability may be difficult.

Difficult-to-read codes create EV battery inspection challenges because codes must be verified for accuracy and legibility. If marked data can’t be visually inspected, traceability is a stake.

Coded data is required to effectively manage product recalls, comply with regulations, and isolate issues of production runs. Therefore, an inspection system must be able to recognize/read poor codes.

Strategies for Overcoming EV Battery Inspection Challenges

Of course, additional challenges might occur when inspecting batteries for defects. How to overcome these challenges depends on the problem and the inspection system used.

Below are a few ways or strategies to test electric vehicle batteries for quality assurance.

Electrical testing

Typical tests include high potential tests (to verify insulation integrity) and welding micro resistance tests (to check battery cell connections).

Optical inspection

Optical tests check the physical condition of the batteries. For example, wire welding inspections determine the quality of wire welds within the battery pack. Material absence, gaps, scratches, and irregularities are also areas of focus in optical checks.

Geometrical measurements

The planarity or flatness of components like separators, electrodes, and battery casing is checked during the geometrical test. Laser profilers are often used during this measurement procedure.

Thermal testing

The temperature response of battery cells in cold, hot, and other weather conditions is tested via this inspection strategy. Temperature control is important to prevent the risk of fire hazards and system failure in extreme temperature conditions.

Best Practices for Effective EV Battery Inspection

Some best practices to employ during EV battery inspection include performing inspections at critical process points, keeping accurate documentation, and utilizing specialized equipment such as measurement sensors.

One critical process point in EV battery production is the assembly of battery cells into modules. It’s essential to inspect if cells are lined up properly and spaced properly to prevent short circuits and other issues.

A laser displacement sensor can measure the distance between cells and verify their alignment. By performing this inspection at this crucial stage, manufacturers can prevent defective components from reaching the next stage of production or a bad product from reaching final assembly.

Rework costs (and associated delays) can be avoided by identifying and correcting issues early in the manufacturing process.

Keeping accurate documentation can help with traceability throughout the supply chain. Using the right equipment for inspection efforts will also help with the speed, accuracy, and efficiency of inspection efforts.

Another practice that deserves attention is prompt attention to problems. Detected issues should be addressed as quickly as possible to prevent simple issues from compounding into bigger problems. Even when faced with significant challenges, allocating sufficient resources to correct problems as they appear is crucial.

Timely response to difficulties will not only help achieve effective and efficient EV battery inspections now but also aid in overcoming EV battery inspection challenges in future operations.

Ensuring Long-Term Success in EV Battery Inspection

Achieving sustainable success with the inspection of different EV battery systems depends on several factors, including the equipment utilized.

Though human input is required, the bulk of inspection for systems like battery cells, modules, and packs is done using automated solutions. These automated solutions not only improve the efficiency of inspections but also enhance consistency, reducing the risk of human error in inspection efforts.

KEYENCE offers a range of measurement solutions ideal for different aspects of an EV battery inspection. Our measurement sensors for the EV industry can, for example, be used to inspect the alignment of battery components during assembly. KEYENCE’s laser profiler can perform 2D/3D measurements of height difference, angle, and width using a single sensor.

For more information on our high-precision measurement products and how they can be applied in EV battery production lines, contact us today.