Aimil Ltd. is an esteemed organization celebrated for its exceptional expertise spanning multiple domains such as electric vehicle battery testing (both electrical and mechanical), coating and inspection, civil engineering software, traffic monitoring and safety, data acquisition, condition monitoring and alignment, power electronics, and medical instrumentation equipment, occupies a prominent position within its industry. During an insightful interview conducted by Himanshu Vaibhav, a Technology Journalist of timesEV.com, Mr RK Mohanty, Product Manager – EV/EVSE Test solutions of Aimil Ltd., provided valuable insights into the intricate aspects of electrical and mechanical testing of EV batteries, along with an exploration of the challenges encountered by the company throughout the testing process.
TimesEV: Provide comprehensive information regarding the testing equipment utilized in electrical testing.
RK Mohanty: When we speak about vehicles, The trend suggests that the consumer’s approach towards a car is not different from a gadget. They want it to be smart, keep up with time with regular updates and meet the basic need of commute. This brings a lot of challenges for test engineers responsible for Mechanical, Electrical, Electronics & Software associated with a unit. With the evolving e-mobility segment the demand for comprehensive testing on the Electrical side has become paramount. There are a series of standards which govern the test conditions and qualification criteria, however, here are the regular types of equipment required in electrical testing,
- Battery capacity test systems (Cell & Pack cycles)
- BMS test system (Battery cell simulators)
- Hardware in loop test systems for a test of subsystems
- Software in loop test systems
- Drive & power train test dynamometers
- Charging standard compliance tester/simulator
- Safety test systems(Insulation, impedance, earthing..etc )
- Regenerative grid simulators and power supplies
- Road load data acquisition (accumulation of electrical and mechanical behaviours)
TimesEV: Provide a concise summary of the mechanical testing conducted on electric vehicle batteries.
RK Mohanty: There are well-established guidelines provided in standards such as AIS, ISO, UN, UL, etc for batteries and their safe operation in vehicular conditions. The industry is very well versed and is employing best practices in qualifying their products to meet the operational, environmental and safety requirements. Some of these tests are
- Vibration test to check the robustness and durability
- Mechanical integrity and shock test
- External/internal short circuit test
- Thermal shock
TimesEV: Provide details about the tests conducted to evaluate a battery’s ability to withstand sudden impacts or collisions.
RK Mohanty: These tests are primarily done at component, sub-system and system levels. The standards recommend tests like impact/shock test, vibration, nail penetration test, etc to understand the behaviour and integrity of the battery & cells. Furthermore, there are safety tests/impact tests conducted at the vehicle level to assess the mechanical & electrical integrity.
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.
RK Mohanty: These tests are carried out in a controlled atmosphere to understand the behaviour of different chemistries and packaging of cell technologies using specially built machines where an extrapolated load is applied to analyze the change in chemical and electrical characteristics at the cell/pack level.
TimesEV: Provide comprehensive information about the procedure involved in conducting electrical testing for electric vehicle batteries.
RK Mohanty: When we talk about the presence of higher voltage and current Safety takes the front seat. Most tests done in HV are safety and performance related. Some major tests are insulation & isolation resistance, HV impulse test, Power and efficiency tests, leakages and RCD, etc. When we speak of charger and vehicle interface during the charging process the test procedures and test cases are well defined in standards such as IEC, IS & DIN. Furthermore, there is a body of experts such as CHARIN who also recommend the best test methods to ensure a safe & efficient charge process.
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.
RK Mohanty: To know or optimize the battery’s performance one should look at capacity i.e the amount of charge a battery can store, Voltage which defines the force with which the electrons flow, energy density meaning the amount of energy the battery can store per unit volume or mass, life cycle states several time a battery can charge & discharge, self-discharge, charging time, efficiency test helps in understanding how much energy is lost in form of heat during charge/discharge and temperature range which helps optimize the battery performance.
TimesEV: Provide a concise overview of the process involved in evaluating and comprehending the electrochemical properties and behaviour of batteries.
RK Mohanty: Well, the evaluation of electrochemical properties is not too different from testing a battery as mentioned earlier. The tests are carried out to understand the thermal characteristics which explain the ability of chemistry to deal with the heat generated during the charge/discharge process, rate capability, cycle life, power & energy density, capacity, etc.
TimesEV: What are the key challenges encountered by testing engineers during the execution of mechanical and electrical testing for electric vehicle batteries?
RK Mohanty: One of the major challenges faced today is the infrastructure. The industry certainly is interested to implement best of the testing facilities practised across the globe however it is primarily driven by the consumer. The current customer trend in EV purchases is a price-sensitive one. When value overtakes the decision-making process over price things ought to improve. However, The industry is well in compliance with required test standards. Furthermore, The knowledge base is getting wider each passing day. This shall help the manufacturers to establish their own standard which is often the best as they may have to compete in the global market.