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e-Drive Leak and Functional Tester
JWF Reference (Partnership)

Battery Test Bench

Test stands for battery leak testing using helium for several German OEMs
JWF Reference (Agency)

Permanent leak tightness (IP67) is a key prerequisite of batteries used in e-mobility. Testing must produce safe and reliable results to avoid short circuits due to splashing. Helium leak testing has a major advantage over air leak testing: It is able to detect even very small leaks (ca. 2.5 cm³ at 50 mbar). There is very little helium in the ambient air, enabling reliable test results even when only slightly increased concentrations of the gas can be detected.

The helium sniffing test uses a sniffer probe to scan all possible leakage points of a test part filled with helium, enabling it to particularly reliably and accurately detect and later repair possible faults. The concentration of the helium/gas mixture can vary depending on the task at hand, making it possible to use it cost-efficiently. JW Froehlich has decades of experience in this field.

A German OEM required test stands which are able to safely test large quantities of components in very little time to start serial production of truck batteries. Their requirement was maximum product and process safety at optimum cost efficiency. A solution for tailor-made and automated test stands for two different locations was developed in close collaboration with the client, and delivered within eight months. Based on these developments, another 20 helium leak test stands were ordered at a later date. Further lines will be equipped by the end of 2024, bringing the total number of helium leak test stands to 30.

1

Overview

For the preliminary test of the incompletely assembled batteries, information is read out from the individual modules, compared with defined limit values, and evaluated. The cell modules are checked for correctness, grade purity and position, the cell voltage and temperature are compared with the limit values, and the self-discharge rate for each battery cell is established. A condition assessment of the battery is always carried out on the basis of these data, which allows for potential risks to be identified early on, and for the battery to be removed from the test station according to the operator’s emergency plan.

Following the leak testing of the battery box and thermal management using air or – for very small permissible leak rates – using a helium sniffing test, the final electrical tests of the completely assembled battery pack are carried out using an EOL test. Once the connection with the battery management system has been established (usually via CAN communication), various electrical quality assurance tests are carried out.

Furthermore, JW Froehlich offers individual mapping for the determination of the ideal leak tightness test procedure for battery components such as housing, cooling systems, rupture discs, etc.

2

Test Procedure

  • Inserting the battery into the helium leak test station
  • Positioning of test part
  • Closing roller shutters
  • Contacting and sealing the battery (manually or automatically, depending on the station’s design)
  • Filling battery with helium
  • Concurrent testing routine (subsurface measurement, nozzle measurement of sniffer lance, calibration leak test, capillary leak test)
  • Waiting to observe penetration time
  • Sniffing battery using robotcontrolled sniffing lance of mass spectrometer
  • Venting and decontacting the battery
  • Opening roller shutters of helium leak test station
  • Removing battery from the test stand, concurrent change of ambient air in the station.
3

Test Methods & Characteristics

Test Method

  • Helium sniff test with Inficon mass spectrometer XL3000flex

Test Characteristics

  • Leakproof seams
  • Various screws
  • Electrical plug on battery management system (LV and HV components)
  • Rupture discs
  • Weld seams

4

Specifications

Downloads

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