JW Froehlich is an expert for quality assurance in series production developing test stands that include pre-testing as well as the end-of-line testing of batteries. Following the electrical pre-tests of the batteries or modules before they have been fully mounted to form a battery pack, leak testing using air or helium sniffing tests, followed by EOL functional tests are performed. Batteries that do not fully meet the test criteria are subjected to repeat tests following repair.

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.

Test methods and contents
  • by air (pressure decay or mass flow procedure)
  • by helium sniffing test (detects minute leak rates and individual leaks, robotic automation possible)
  • Reading out of various battery module information
  • Tests for correctness and grade purity in combination
  • Assignment of assembly position within the housing
  • Testing cell voltage and temperature
  • Testing selfdischarge rate for each battery cell
  • Battery condition assessment
  • Reading out and testing of various battery pack information
  • Voltage resistance measurement
  • Insulation resistance measurement
  • Residual voltage measurement
  • Insulation monitoring testing
  • Operating/quiescent current testing
  • HV voltage measurement and testing of HV contactor/switches
  • Load test (charge and discharge cycles)
  • Permanent battery condition assessment

Our test stands and test systems are equipped with leakage test devices developed by our company, which are optimally integrated into the test process.