Identifying and addressing high voltage leaks in electric vehicles (EVs) is paramount for the safety and efficiency of the vehicle. This procedure outlines the steps necessary to locate and rectify any high voltage leaks.
Safety Precautions
Before commencing any testing, it is crucial to adhere to the following safety measures:
- Personal Protective Equipment (PPE): Wear insulated gloves, safety goggles, and appropriate protective clothing.
- Isolation: Ensure the vehicle is isolated from the main power supply and turned off. The keys should be removed and kept away from the work area.
- Warning Signs: Place warning signs around the work area to alert others of high voltage testing in progress.
- Emergency Protocols: Familiarize yourself with emergency procedures in case of an electric shock or other incidents.
Required Tools and Equipment
Gather the following tools and equipment before beginning the testing procedure:
- Insulation resistance tester (megohmmeter) capable of 1000V test voltage and insulation testing from .01 MΩ to 2.0 GΩ (Minimum CATIII)
- HV rated tools to remove screws from battery fuses
- Safety Glasses
- High voltage safety gloves rated for >1000 VDC and insulating mats
- Service manual for the specific EV model
Testing Procedure
Step 1: Prep Testing Site
- Move Vehicle to a dry and level location.
- Power of the vehicle and wait 15 minutes for the systems to discharge.
- While wearing the appropriate PPE, remove the MSDs from the S-Box and wait 15 minutes
Step 2: Visual Inspection
- Perform a thorough visual inspection of the vehicle's high voltage components. Look for any signs of physical damage, corrosion, or wear on cables, connectors, and insulation.
Step 3: Isolation Verification
- Ensure that the high voltage system is completely isolated. Use the multimeter to check for any residual voltage in the system before proceeding.
Step 4: Insulation Resistance Testing
- Set the insulation resistance tester to the appropriate voltage range as specified in the vehicle's service manual.
- Remove back cover on ePDU
- Connect negative lead to chassis ground and perform isolation test on each high voltage cable and record values.
- Perform isolation test on ePDU and record values.
- If low isolation is found, determine if component failure of cable failure and replace suspect cable/component.
Step 7: Documentation and Reporting
- Document all findings, including resistance values, voltage readings, and identified leaks.
- Provide a detailed report outlining the location and nature of the high voltage leak.
- Include recommendations for repairs or replacements as needed.
Alternate Method without Insulation Tester
Step 1: Prep Testing Site
- Move Vehicle to a dry and level location.
- Disable HVIL on vehicle.
Step 2: Visual Inspection
- Perform a thorough visual inspection of the vehicle's high voltage components. Look for any signs of physical damage, corrosion, or wear on cables, connectors, and insulation.
Step 3: Isolation Verification
- Ensure that the high voltage system is completely isolated. Use the multimeter to check for any residual voltage in the system before proceeding.
Step 4: Component Testing
- Power off vehicle and wait 15 minutes for vehicle to discharge.
- Unplug a high voltage component from the ePDU
- Power on vehicle
- Does low isolation DTC clear? If DTC does not clear, start restart Step 4: Component Testing disconnecting a new component. If DTC clears, continue.
- Power off vehicle.
- Reconnect all precious components except the last one disconnected.
- Power on vehicle.
- Does low isolation DTC clear? If DTC does not clear, start restart Step 4: Component Testing disconnecting a new component. If DTC clears, continue.
- Determine if cable or component has low isolation and replace.
Conclusion
Locating a high voltage leak in an electric vehicle is a meticulous process that requires careful attention to detail and adherence to safety protocols. By following this procedure, technicians can accurately identify and address high voltage leaks, ensuring the safe and efficient operation of the vehicle.