Testing and Diagnostic Technology for E-Mobility and Alternative Powertrains

Frequently Asked Questions About E-Mobility, High-Voltage Systems, and Electric Vehicles

Electric and hybrid vehicles require new testing procedures and specialized workshop equipment. The following questions provide an overview of high-voltage battery diagnostics, state of health, leak testing, thermal management, electrical safety, charging technology, and fuel cell systems.

• What testing equipment does a workshop for electric vehicles need?

  The testing equipment required depends on the specific task and the vehicle manufacturer’s specifications.

  Typical testing and service tasks for electric and hybrid vehicles include, among others:

  • Assessing the condition of a high-voltage battery
  • Leak testing of battery housings and high-voltage components
  • Testing, evacuating, and refilling of cooling and thermal management systems
  • Testing coolant quality and electrical conductivity
  • Electrical safety and insulation measurements
  • Testing of wall boxes, EVSEs, and charging cables

  Autotestgeräte Leitenberger offers a variety of specialized testing and service equipment for these applications.

• What is a high-voltage battery?

  The high-voltage battery, also known as the traction battery, stores the electrical energy used to power an electric or plug-in hybrid vehicle.
  
  In addition to the actual battery cells, the battery system includes—depending on the vehicle—components such as the battery housing, electrical connections, sensors, control unit, cooling system, and the Battery Management System (BMS).
  
  Due to the high electrical energy involved and the safety-critical functions, special work procedures and appropriate test equipment are required for diagnostics and service.

• How can you check the condition of a high-voltage battery?

  An important metric for evaluating a high-voltage battery is the State of Health (SoH).

  Depending on the test procedure, relevant battery data can be retrieved from the Battery Management System via the OBD interface, or additional dynamic battery data can be collected during a defined drive.

  The Leitenberger HVBD 01_LR enables—depending on the supported vehicle model—both a stationary SoH readout and a drive test.

  For more information, see High-Voltage Battery Diagnostics and State of Health (SoH) Testing.

• What does “State of Health” (SoH) mean for an electric car battery?

  The State of Health (SoH) describes the health or aging status of a battery relative to a defined reference state.
  
  The SoH is often expressed as a percentage.
  
  How the value is determined depends on the test method used and the available battery data. Therefore, an SoH value read from the BMS and an independent dynamic assessment do not necessarily have to be based on the same calculation method.

• What is the difference between SoH and SoC?

  SoC – State of Charge describes the battery’s current state of charge.

  SoH – State of Health, on the other hand, describes the battery’s long-term health or state of aging.

  To put it simply:

  The SoC answers the question “How full is the battery?”

  The SoH answers the question “What is the battery’s condition?”

• Why is the SoH becoming increasingly important for used electric cars?

  Age and mileage alone do not provide a complete assessment of a high-voltage battery’s condition.
  
  Battery aging can be influenced by factors such as usage, temperature, charging behavior, and operating conditions.
  
  A transparent SoH assessment therefore provides additional clarity during purchase, sale, lease return, vehicle appraisal, and fleet management.

• Is a SoH battery certificate the same as the EU Battery Passport?

  No.

  An SoH report or battery certificate documents the determined condition of a specific high-voltage battery at the time of testing.

  The EU Battery Passport, on the other hand, is a legally defined digital record under the EU Battery Regulation and contains significantly more comprehensive information about the battery.

  For relevant electric vehicle batteries, the Battery Passport will become mandatory as of February 18, 2027.

  An SoH test therefore does not replace the EU Battery Passport.

• Why is it necessary to check the leak-tightness of a high-voltage battery?

  The battery housing protects sensitive high-voltage components from external influences.

  After certain repair, disassembly, or maintenance work, a leak test may therefore be necessary to verify, in accordance with the vehicle manufacturer’s specifications, whether the housing or the affected component is sufficiently leak-tight.

  You can find suitable test equipment under Leak testers for HV batteries and high-voltage components.

• What methods are available for leak testing high-voltage batteries?

  Depending on the component, the vehicle manufacturer’s specifications, and the test requirements, different methods may be used.

  These include, for example:

  • Pressure testing
  • Vacuum testing
  • Pressure drop testing
  • Flow rate or leak rate measurement
  • Leak detection using a suitable test gas

  The permissible test pressure and the test method specified by the manufacturer are always critical.

• Why is thermal management important for electric vehicles?

  The high-voltage battery and other components of the electric powertrain operate within defined temperature ranges.

  Depending on the vehicle, the thermal management system cools—and in some cases also heats—the battery, power electronics, and other components.

  Therefore, proper refilling is essential after work on the cooling system. Trapped air, incorrect coolant, or leaks can impair the function of the thermal management system.

  You can find suitable devices under Thermal Management and Coolant Testers for Electric Vehicles.

• Why is the electrical conductivity of coolant measured in electric vehicles?

  For certain coolants used in high-voltage and fuel cell systems, low or defined electrical conductivity is one of the key properties.
  
  Aging, contamination, or mixing with an unsuitable medium can alter the electrical conductivity.
  
  A suitable conductivity meter can therefore be used to verify whether the measured value falls within the limits specified by the vehicle or coolant manufacturer.

• Are all coolants for electric vehicles the same?

  No.
  
  Different coolant technologies are used depending on the vehicle and cooling system.
  
  In addition to conventional or specially formulated water/glycol-based EV coolants, there are low-conductivity coolants as well as dielectric thermal fluids for specialized direct cooling systems.
  
  Therefore, coolants must not be selected or mixed together based solely on color or general product names. The vehicle manufacturer’s approval is the determining factor.

• What is an insulation test on an electric vehicle?

  An insulation test evaluates the electrical insulation condition of a high-voltage system or a component designed for such a system.

  This test is an important part of certain electrical safety and diagnostic tasks on high-voltage vehicles.

  Test procedures, test voltage, and limit values depend on the specific application and the relevant specifications.

  You can find suitable devices under HV Safety and Electrical Tests on Electric Vehicles.

• Is UN ECE R100 a workshop testing regulation?

  Not in the sense of a general work instruction for every maintenance or repair task.
  
  UN Regulation No. 100 sets forth requirements for the approval of vehicles with regard to electric propulsion and the safety of rechargeable electrical energy storage systems.
  
  Among other things, it includes requirements and test procedures for insulation resistance.
  
  However, the specific measurements a repair shop must perform during a particular repair depend primarily on the vehicle manufacturer’s specifications, the scope of work, and the relevant occupational safety and qualification requirements.

• Who is authorized to work on high-voltage vehicles?

  Work on vehicles with high-voltage systems requires qualifications appropriate to the specific scope of work.
  
  DGUV Information 209-093 describes a qualification framework for this purpose and distinguishes, among other things, between different levels of work and qualification.
  
  The required qualification depends on the specific work to be performed and the condition of the high-voltage system.

• Is every multimeter suitable for working on high-voltage vehicles?

  No.
  
  The measuring instrument, test leads, measurement category, voltage range, and measurement method must be suitable for the specific test task.
  
  In addition, the required qualifications, personal protective equipment, and the specifications of the vehicle and measuring instrument manufacturers must be observed.

• What is the difference between an HV vehicle inspection and a wallbox inspection?

  During a high-voltage vehicle inspection, the electrical properties and safety conditions of the vehicle or high-voltage system are examined.

  A wallbox or EVSE, on the other hand, is part of the charging infrastructure and serves as an electrical interface between the power supply and the vehicle.

  Special EVSE test adapters and test equipment are used for this purpose.

  You can find suitable devices under Wallbox, EVSE, and Charging Cable Test Equipment.

• What does EVSE stand for?

  EVSE stands for Electric Vehicle Supply Equipment.

  This term refers to devices that connect an electric vehicle to an external power source or control the charging process safely.

  These include, for example, wall boxes and other AC charging stations.

• Can Mode 3 charging cables be tested?

  Yes. Special test adapters are available for electrical safety and functional testing of Mode 3 charging cables.
  
  Depending on the test equipment, it is possible to check, among other things, continuity, resistance, and insulation condition.

• What is the difference between indirect battery cooling and immersion cooling?

  In indirect liquid cooling, the coolant flows through cooling plates, channels, or heat exchangers. The battery cells or electrical components through which current flows are not in direct contact with the cooling medium.

  In immersion or direct cooling, on the other hand, the components to be cooled are in direct contact with a suitable dielectric thermal fluid.

  Both systems place different demands on the cooling medium, service equipment, and materials.

• What is a low-conductivity coolant, or LECC?

  LECC stands for Low Electrical Conductivity Coolant.

  This is a coolant with low electrical conductivity designed for use in appropriately engineered electric or hybrid vehicle cooling systems.

  LECC should not automatically be equated with a dielectric coolant used for true immersion cooling.

  The specific coolant and its handling always depend on the specifications provided by the vehicle or coolant manufacturer.

• What types of testing are required for fuel cell vehicles?

  In fuel cell vehicles, in addition to high-voltage technology, thermal management and coolant quality play a particularly important role.

  For fuel cell cooling systems designed accordingly, factors such as filling the system and monitoring concentration and electrical conductivity may be relevant.

  You can find suitable devices under Thermal Management and Coolant Testing for Fuel Cell Vehicles.

• Can standard workshop tools also be used on electric vehicles?

  In some cases, yes—but not automatically.
  
  The key factor is whether the specific test, measurement, or service equipment is approved or technically suitable for the particular application, voltage range, fluid, and vehicle.
  
  In particular, when working with high-voltage systems, low-conductivity coolants, and safety-critical tasks, the relevant manufacturer’s and safety specifications must be followed.