Automotive Test Systems stands as a trailblazing company with an extensive and diverse background in Product Validation, Structural Testing, Data Acquisition and Analysis, Vehicle Handling & Performance evaluation, NVH Testing, and Power Train Testing. In a recent interview conducted by Himanshu Vaibhav, Technology Journalist from ELETimes and timeEV.com, Dr Manoj Modani, Director of Automotive Test Systems, delved into the intricacies of electrical and mechanical testing of EV batteries, as well as the cutting-edge technologies employed in the testing process and other pertinent aspects.
TimesEV: Provide comprehensive information regarding the testing equipment utilized in electrical testing.
Dr Manoj Modani: Electrical test equipment includes a Motor test rig, eAxle test rig, Chassis dyno, Battery s2imulators or Bi-Directional Power supplies Data logger, Battery cyclers, Power analyzer with Voltage & current sensors, Temperature loggers, Coolant conditioning systems for controlling the Temperature of the batteries. The state-of-the-art facility at our Technical Centre in Bangalore has the above test equipment sourced from Europe which is accurate and rugged. It can test components of high power ratings up to 257 kW.
TimesEV: Provide a concise summary of the mechanical testing conducted on electric vehicle batteries.
Dr Manoj Modani: Ingress Protection (IP Test), Impact test, drop test, crush test, mechanical shock test, mechanical integrity test, random vibration test, electromagnetic vibration, a rollover test, nail penetration test, Gravel Bombardment test, Salt Water Spray Test. etc.
The cycles for the tests such as Random Vibration, Mechanical shock, etc. depend on the vehicle category in which the battery pack is going to be used, as the size & weight of the battery matter for such testing. Also normally these tests are done with the batteries either in fully charged or 50% charged conditions.
ATS is proud to inform you that we have signed MOU with govt. of Telangana to develop a world-class test facility near Hyderabad and TUV is our partner for the same. Once up it will be the best in the whole of India.
TimesEV: Provide details about the tests conducted to evaluate a battery’s ability to withstand sudden impacts or collisions.
Dr Manoj Modani: Mechanical shock/impact test as per test standards IEC62133, UN38.3, UL 1642:2012, AIS 038, AIS 048, AIS 156. Where in different Ramp rates, Frequencies for testing are used based on the battery size, weight & vehicle category in which the battery pack shall be used.
TimesEV: Provide detailed information about the test that assesses the battery’s capability to withstand the compression forces that can arise during a vehicle accident.
Dr Manoj Modani: The important tests as per AIS AIS 038, AIS 048 & AIS 156 are thermal propagation, short circuit, fire resistance test, protection against electrical shock, protection against water flooding
TimesEV: Provide comprehensive information about the procedure involved in conducting electrical testing for electric vehicle batteries
Dr Manoj Modani: Electrical testing for electric vehicle batteries includes Life cycle Durability testing to determine the Charge retention capability, Cell Balancing ability of the Battery pack, External short circuit protection, Over charge protection, Over discharge protection, Over temperature protection, over-current protection, thermal propagation etc.
TimesEV: Provide a succinct overview of the electrical test employed to estimate the battery’s performance and useful life across multiple charging and discharging cycles.
Dr Manoj Modani: Based on the manufacturer’s battery design, the batteries are subjected to life cycle durability tests where batteries are subjected to several Charging & Discharging cycles which are performed over some time/cycles ex. 500 or 1000 cycles. Which runs into a few thousand hours of testing. During these cycles, different Charging & discharging rates such as 1C, 2C etc. are selected. During the entire trial Thermal conditions or Temperature of cells, Battery module & pack level are being monitored. These tests are mainly performed to estimate the battery life & electrical charge-holding capability of the cell & also the pack level.
The state of charge of a battery describes the difference between a fully charged battery and the same battery in use. It is associated with the remaining quantity of electricity available in the cell. It is defined as:: the remaining charge in the battery/ the maximum charge that can be delivered by the battery X100
The state-of-health (SoH) of a battery describes the difference between a battery being studied and a fresh battery and considers cell ageing. It is defined as:: the maximum battery charge available of the battery / rated capacity of the new battery X100
TimesEV: Provide a concise overview of the process involved in evaluating and comprehending the electrochemical properties and behaviour of batteries.
Dr Manoj Modani: Li-ion batteries have become one of the most widely used energy storage devices due to their high energy and power densities. However, their applications are limited by the performance limitations. Higher performance will result in serious polarization which is caused by mass transport limitations within the electrolyte and electrodes. The impact of each process on the polarization is dependent on the dynamic and kinetic material properties, the battery design and the charging-discharging mechanism. The relationship between the influencing factors and the polarization is very complex and is done by a complex mathematical model. In a nutshell, the electrochemical properties of batteries are evaluated by the energy it stores and the power density (power it delivers, per kg of weight)
TimesEV: What are the key challenges encountered by testing engineers during the execution of mechanical and electrical testing for electric vehicle batteries?
Dr Manoj Modani: Safety against explosion/fire is a major concern, and we provide a safety enclosure while testing high-power batteries. Ongoing changes in technology and test standards are another challenge – which is part of any new development. ATS has joined hands with NATRAX Indore to offer advanced testing and certification services. MOU has been signed recently for the same.