Why Introduce SWIR Sensors into Electric Vehicle Battery Production Monitoring and Quality Control Testing?
To ensure that electric vehicle batteries meet the strict safety, performance, or quality requirements, it is crucial to conduct quality control testing on them. Currently, leak detection methods are slow and inaccurate, and even tiny leaks can shorten the battery’s life, impact performance, and increase warranty costs. Even worse, leaking can shortcircuit electrical systems, set fires, or cause damage to battery components.
A battery can be non-destructive tested before it leaves the factory. Automated radiographic inspection (X-ray inspection) can be used to examine hidden inner structures and identify defects before the cells leave the factory. This prevents defective cells becoming part of battery modules. The cell structure is also important for quality control. Rolled cells can be examined in 2D. Stacked cells, however, require 3D computer tomography. This is more difficult than interpreting a transmissive radiograph image.
Engineers assess a battery’s condition during manufacturing by measuring the state of charge or discharge. Engineers also assess the condition of the battery’s battery’s busbar. This is a conductor that is long and isolated from the ground. It is responsible for discharging current throughout the battery pack. Because the weld resistance of batteries is an important indicator, testing the busbar is an essential part of the process. Any resistance that is too low can lead to excessive heat and early failures. By measuring the resistance before a battery is operational, engineers can remove any defective modules in the shortest time possible.
In addition to performance testing, SoC information is critical to estimate a battery pack’s usable life. It is possible to reduce the usable life of a lithium-ion battery pack by charging it too often or discharging it too frequently. This information is also used by the battery management system (BMS) to maintain the cells within their safe operating limits. BMS must also include a precise charge estimator to calculate SoC.
SoC can’t be measured directly, unlike voltage and temperature. It must be calculated using proprietary parameters.
SWIR can be used to adapt the Lithium-Ion Battery Testing Process
In terms of testing equipment suitable for adaptation to existing production systems, high resolution, wide field-of-view, and extended SWIR cameras can be utilized to overcome important lithium-ion battery inspection challenges, therefore enabling lithium and lithium-ion battery producers to meet increasingly demanding performance and quality specifications.
SWIR Vision’s Acuros SWIR cameras, for example, can provide imaging through the Li:Ion separator using SWIR wavelengths. These cameras – or sensors – provide the necessary alignment accuracy of inter-layer electrodes leading directly to more available energy storage capacity and longer battery lifetimes.
These sensors are able to see through objects and provide high-resolution images at a fast-fire rate. This makes them ideal for quality control throughout the manufacturing process. We expect SWIR cameras to be adopted quickly for battery testing.