Electric vehicle work safety section covers some risks when working with electricity or electrical system, together with suggestions for reducing them. This is known as risk assessment. The diagnostics process is o different but avoid working on high voltage vehicles unless you are trained and have specialist equipment-stay safe.
Electric vehicles (Pure or Hybrid) use high voltage batteries so that energy can be delivered to a drive motor or returned to a battery pack in a very short time. Voltages of 400V are now common and some are up to 700V. So, clearly there are electrical safety issues when working with these vehicles. High voltage means the classification of an electric components or circuit if its working voltage is >60V and <_1500V DC or >30V and <_1000V AC root means square (rms). High voltage can also be present on vehicles without high voltage batteries such as headlamps that use ballast resistors for example.
EV batteries and motors have high electrical and magnetic potential that can severely injure or kill if not handled correctly. It is essential that you take note of all the warnings and recommended safety measures outlined by manufacturers. Any person with a heart pacemaker or any other electronic medical devices should not work on an EV motor since the magnetic effects could be dangerous. In addition, other medical devices such as intravenous insulin injectors or meters can be affected.
The electrical energy is conducted to or from the motor via thick orange wires connected to the battery. If these wires have to be disconnected, SWITCH OFF or DE-ENERGISE the high voltage system. This will prevent the risk of electrical shock or short circuit of the high voltage system.
Electrolytes used in EV batteries can be harmful and it is important to remember that both acid and alkali solutions are used in this technology. Understanding before you start work what type of chemical I present will enable selecting the correct procedure when dealing with a spill.
Stages of Electric Vehicle Work Safety
The general advice about working on high voltage vehicles is split into four areas-
Turn OFF the ignition switch and remove the key.
- Switch OFF the battery module switch or de-energies the system
- Wait for 5 minutes before performing and maintenance procedures on the system. This allows any storage capacitors to be discharged
- Isolate system and stow key in safe location only accessible to the technician.
Always wear correct PPE when there is risk of touching a live component.
- Always use insulated tools when performing service procedures to the high voltage system. This precaution will prevent accidental short-circuit.
- Always use correct workshop equipment to define the work area, warning others of the dangers present and use a correct insulated rubber mat when appropriate.
When maintenance procedures must be interrupted while some high voltage components are uncovered or disassembled, make sure that-
- The key is only accessible with the working technician’s knowledge
- The battery module switch is switched of
- No untrained persons have access to that area and prevent any unintended touching of the components.
Before switching on or re-energizing the battery module after repairs have been completed, make sure that-
- All terminals have been tightened to the specified torque
- No high voltage wires or terminals have been damaged or shorted to the body
- The insulation resistance between each high voltage terminal of the part you disassembled and the vehicles body has been checked.
Safety training is essential for any type of electric vehicle before repair or maintenance due to its high voltage.