In this exclusive op-ed for The Manufacturer, Keysight Technologies’ Christian Loew explores how intelligent test automation and early-stage validation can help EV manufacturers balance battery pack safety, quality and throughput while reducing production costs and risks.
In Electric Vehicle (EV) production, a small number of gating test functions ultimately determine yield, safety, and time to market, with battery pack validation among the most critical. The primary objective is to perform all required tests as fast as possible, as throughput is the most critical (and expensive) factor in production. However, the challenge lies not only in the number of tests that must be covered, but also in the time they typically require in a conventional lab environment. In general, the goal is always to keep the test time as low as possible while ensuring all parameters are tested vigorously to ensure the highest quality output.
Testing early to reduce cost and risk
As battery systems scale in complexity and cost, manufacturers are increasingly pushing quality validation earlier in the process by expanding functional and parametric testing at the cell and module levels. By verifying electrical performance, safety limits, and consistency before final pack assembly, defects can be detected when they are still inexpensive to correct. This testing strategy significantly reduces the risk of discovering faults after pack integration, reducing rework, scrapping, or disassembly. But early testing of cells and modules does not eliminate the necessity of performing functional, safety, and performance tests after final assembly.
For the fully assembled battery pack, a wide range of tests needs to be performed. Functional tests such as Battery Management System (BMS) verification are relatively manageable in terms of time and complexity. It primarily involves communication checks, firmware validation, and serial number verification. More hardware-intensive tests include leakage detection in the cooling circuit of the battery packs and isolation testing (HiPot), which are not only time-consuming but require specialized equipment.
The real limiting factor is the functional validation of the charging and discharging behavior, along with battery capacity testing. These processes are time-intensive and demand high power. If a certain operational point needs to be tested, the charging rate (current) cannot be arbitrarily accelerated due to chemistry- and design-imposed current limits. Even if charging the packs is not required, most transportation safety protocols require a discharge to a safe stage (20 to 30% State of Charge).
Each battery design and chemistry has specific charge and discharge characteristics that cannot be exceeded, and testing according to them is critical to ensure safety, as well as provide reliable data. The strategy in production therefore relies on parallelized testing and charge/discharge processes, increasing throughput at the expense of higher hardware investment, energy consumption, and floor space. The optimal approach lies between extremes: combining sufficient power resources with intelligent switching and automation to balance parallelism, cost, and efficiency.
The role of test automation in high-volume production
What is ultimately required to ensure gapless operation for such connected test benches is an automation platform that delivers fast, repeatable, and adaptive execution while allowing engineers to precisely fine-tune test sequences to the requirements of each device under test. Two purposes need to be fulfilled: Integration of all needed test equipment in a flexible and deep manner without limitations, as well as a final user interface that allows operators to safely, intuitively, and confidently perform in-line and end-of-line tests.
With these basics given, modern platforms extend the functionality in the backend with tools for faster analysis in cases of failures, big data handling, and pattern recognition to boost early recognition of systematic errors, supporting low failures and highly productive quality assurance.
Balancing speed, quality and safety
In conclusion, early testing of all components helps reduce risk, but packs still need to be tested broadly.
To ensure safety, quality, and longevity of the battery packs, part of the production tests needs to verify operational functionality and communication, leak-free operation of the cooling circuit, sufficient electrical isolation, and proven charge/discharge functionality. Most of the time, the production tests conclude in a discharge down to a safe handling voltage. During production tests, the majority of the time is spent on charge and discharge, and it has the biggest influence on the throughput of the lines.
To ensure smooth operation and optimal alignment between the test steps and different production lines, a test automation platform is key. It helps to automate the test steps, provides an intuitive interface, and supports data handling and data insight in the backend.
About the author
Christian Loew is a product manager in the Automotive and Energy Solutions group of Keysight Technologies, focusing on battery cell, pack, and module test solutions.
Christian holds a degree in Electrical Engineering from the University of Ulm, Germany.
