Within the automotive sector, electromobility encompasses various vehicle concepts that differ in terms of their design and energy supply. The following overview sums up the most important types.
| Vehicle type | System voltage | Main features |
| Mild Hybrid (MHEV) | 42V to 150V | Start/stop function, recuperation, electric boost support, no fully electric driving |
| Hybrid Electric Vehicle (HEV) | > 100 V | Recuperation, boost, limited electric driving, no external charging function |
| Plug-in Hybrid Electric Vehicle (PHEV) | > 100 V | Combination of combustion engine and electric motor, recuperation, electric driving, external charging option |
| Battery electric vehicle (BEV) | 200V to 1000V | Fully electric vehicle, recuperation, electric driving, charged by external power source |
An electric vehicle features various linked high-voltage and low-voltage components that ensure the electric drive and power supply.
In addition to staff's professional qualifications, the employer bears the main responsibility for the safe performance of work on high-voltage systems.
Key duties include in particular:
Working on electric vehicles requires special care, even if, at first glance, it does not involve high-voltage components. The integrated networking of contemporary systems means that even simple modifications to conventional components can have an impact on the high-voltage system. A structured approach that guarantees the safety of everyone involved at all times is therefore crucial.
A risk assessment must be carried outbefore starting work. It forms thebasis for all protective measures and must be regularly reviewed as well as adapted in the event of safety-relevant changes. The responsibility for this lies with the competent and responsible person in the company or with the employer.
Safe operational processes start with the right preparation:
Applicable personal protective equipment depends on the work due as well as the manufacturer specifications.
PPE must be checked for damage before each use. Do not use faulty equipment.
Exclusively authorised and tested tools must be used for work on high-voltage systems. Tools must comply with the applicable standards, be insulated and have a dielectric strength of at least 1000 V. Visual inspections are mandatory before each use. Exclusively fully tested and undamaged tools guarantee the required levels of safety.
Always check whether the vehicle must be de-energised before starting any maintenance or repair work.Manufacturer specifications must also be observed. Play it safe if you are unsure. The vehicle must be de-energised in accordance with the manufacturer specifications. The safety of anyone involved is the top priority.
Regarding work on high-voltage systems, the recognised five safety rules of electrical engineering apply in an adapted form:
The first three safety rules must always be implemented when working on high-voltage systems. Whether rules four and five are also applicable depends on individual circumstances. Manufacturer specifications must always be observed.
The process of working on electric vehicles differs depending on the vehicle manufacturer. Consequently, the respective manufacturer specifications must always be observed for all activities, including the replacement of 12 V components. Some manufacturers stipulate that the high-voltage system must be de-energised before any intervention in the 12V vehicle electrical system, for example when replacing the intelligent battery sensor. Non-compliance with this specification may cause high-voltage contactors to open under load and be damaged as a result.
The de-energising procedure itself may also differ between the individual manufacturers. While, in one vehicle, de-energising the high-voltage system must be verified and recorded using a suitable measuring device, this condition is confirmed by a display or message in the instrument cluster in another, provided the high-voltage system is not affected by any faults.
The vehicle manufacturer's de-energising and testing instructions must be strictly observed for all work on electric vehicles. This is the only way to guarantee that there is no unwanted voltage and that high-voltage contactors or control units do not suffer consequential damage.
