Maintaining and servicing electric vehicles is different from other fuel cars. This article explores key safety considerations to follow while servicing these high-voltage vehicles. We would like to thank Jinesh Vinayachandran, Academic Advisor, Little Flower Engineering Institute, Kochi for sharing his input on the subject.
The market for electric and hybrid cars is rapidly increasing, and sooner or later they will replace traditional vehicles. With this rising popularity, they bring with them new dangers to the technicians who have to work on them. Most OEMs have readily available service precautions that need to be read and carefully followed before working on their electric vehicles. Still, there are some inhibitions among the auto mechanics. While EVs are no harder to repair than fuel-based cars, specialised training is required on electrical safety, specialised components, and more. Let’s look at some of the unique safety issues with electric vehicle maintenance and repair and how it differs from combustion-engine vehicles.
Voltages above 60-volt DC are considered high voltage and hazardous to human. While electric two-wheelers come under the 48-volt category, the range is between 300 to 800-volt for electric four-wheelers. Because of this increased danger of high voltages, EVs pose special challenges to the collision repair shop.
Electric vehicles contain significant critical wiring that facilitates their operation. Wires running
internally through vehicles are generally divided into two voltage categories – low voltage and high voltage. Low voltage wires are Black in color. High-voltage wires are colored in recognisable Orange to make this danger easily identifiable even for a person with color blindness. Workers should
wear gloves or avoid contact with high-voltage cables unless the high-voltage battery has been disconnected.
Battery packs for an EV can contain several hundred individual cells. Each cell has a nominal voltage of 3.5-4.2 volts depending on the cell chemistry. If proper precautions are not taken, these high-voltage batteries can kill the technician in seconds. Even the electromagnetic field created by permanent magnets inside the electric motor can cause harm to anyone with a cardiac pacemaker or any biomedical equipment or steel implants. Compared to ICE vehicles, servicing EVs requires some particular precautions. Before working on EVs, it should be ensured that the workshop complies with EV safety standards and that the workers received necessary safety training.
Prerequisites for EV workshop safety
- Safety Cone, Danger Sign Board and Simple Barricade Tapes for the work bay to warn people instantly about the possible danger of high voltage system.
- Fibre Rescue Pole that can be used to separate person under electric shock from contact.
- Class D Category Fire Extinguisher for fighting battery fires that involve combustible metals or metal alloys, such as nickel, lithium and cadmium.
- CAT III (Up to 1000V DC) multimeter to measure voltage and resistance.
- Battery charging and discharging equipment.
- Non-metal workbench or insulated workbenches, terminal covers, and insulated mats and covers.
- Battery jack to lower or rise the battery pack from/to vehicle without damage.
- Instructions for what to do in case of emergency like battery fire inside the garage.
- Insulated working tools (up to 1000V DC) and proper diagnostic tools.
Equipment for workers’ safety
- Class 0 (Category Zero – up to 1000V DC) insulated rubber gloves to handle batteries and high-voltage parts while avoiding potentially fatal electric shocks.
- Cotton gloves (also called liner gloves) to absorb sweating inside insulated rubber gloves.
- Leather gloves to protect insulated gloves against heat and sharp objects in the workspace of the vehicle.
- Face shields and Goggles to protect against high voltage leaks and arc flash risk.
- Coverall garment to protect against leaking electrolyte chemicals used in batteries and flying hot metal shrapnel created by electric arcs.
- Non-slippery insulated boots/overshoes.
Also, never wear jewellery while working on an electric vehicle, as it increases the possibility of electrocution and never jack an EV other than its lift points as it may cause crushing HV insulation if such a line passes by.
Safe servicing processes of EV
- Secure the vehicle in a cordoned-off area with appropriate warning signage.
- Lock away the remote operation key to prevent the accidental operation of electrical systems or movement of the vehicle. Check that the vehicle is in a safe condition before the key is retrieved.
- Unplug the service plug to disconnect the battery from HV lines and lock or keep it safe.
- Wait 5-10 minutes before working on the vehicle after the supercapacitors have been discharged.
- Ensure with a multimeter that voltage is between 10 to 0 before starting repair and maintenance.
In readiness for embracing the EV trend, the auto repairing and maintenance industry needs to ensure that adequate safety systems are in place and that all workforce are effectively trained. With the proliferation of EVs, concerned authorities should give proper general awareness training to the public and emergency response tactical training to the emergency responders like Fire Force, Trafic Police, and NGOs for safely handling EV accidents.
-Compiled by: Mahesh Kallayil