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Choosing The Right Company To Carry Out Your Electric Hybrid Battery and High Voltage System Repairs.

Updated: Mar 5

At present there’s no legislation in place to stop unqualified persons from working on high voltage batteries and associated systems and while appreciating that people are generally pre-disposed to want to save money where possible, it should be said, a person wouldn't think repairs on household electrical system was a good idea unless qualified to do so, so why would it seem a good idea to take the same risk while working on vehicle high-voltage systems?

The following guidelines are set out by the Institute of the Motor Industry

Persons Permitted to Carry Out Work On Vehicle High Voltage


L1 Award in Electric/Hybrid Vehicle Awareness

L1 is designed for trainers and employers to promote awareness of the

dangers surrounding and the precautions required to avoid potential

injury while near hybrid electric vehicles.

This course can be delivered online and is aimed at non-technical


L2 award in electric/hybrid vehicle routine maintenance

Working safely around Hybrid Electric vehicles while carrying out routine

maintenance this level of qualification does not allow working on the high

voltage systems.

L3 award in electric/hybrid system repair and replacement

Designed for maintenance and repair technicians. This is the minimum

level award allowing for repair and replacement of components within

the high voltage system.

L4 award in diagnosis, testing and repair of hybrid electric vehicles

For technicians, this qualification is designed to ensure the safety of

technicians testing and working on or near live high-voltage systems.

It is the responsibility of managers and technicians to manage work on

and around high-voltage vehicle systems to ensure this is done in the safest

possible way, following operating procedures, minimising risks, adhering

to safety standards and using correct PPE (personal protective

equipment) and carrying out risk assessments.

DC or direct current is more dangerous than AC alternating current - 99% Of adults will not be able to let go with a current greater than 22 mA


Current in mA

Effects on the Human Body


Electrical Sensation


Painful Shock


Let go threshold for children


Minimum let go threshold for adults


99% of adults cannot let go


Tetany - contact area


Tetany – respiratory muscles


Ventricular fibrillation

1 milliamp = 0.001 of an amp - As an example, a Toyota Prius high-voltage battery can deliver 100 -150 amps for short bursts

The Picture above is of a Toyota battery module which has cracked open during use, causing an isolation fault with an electrolyte leak

Knowing how to keep yourself and customer vehicles safe is of the utmost importance

Although electric/hybrid vehicle systems are generally safe and are designed with safety as a paramount concern and every effort is made to keep anyone who comes into contact with the high voltage system safe, some system faults could be encountered which pose a significantly higher risk of causing injury or death, such as a voltage leak to the chassis of the vehicle where the isolation between the high voltage system and the chassis has become compromised and the voltage can find itself in areas where it is not meant to be found, the outer metal case of a battery as an example, which could be caused by component failure or by water ingress exposing anyone working on batteries to much greater risk if proper safety procedure is not adhered to.

There are other risks which could be encountered and should be considered before work begins on any high voltage system, especially while testing while the system is live. A full risk assessment should completed prior to any work being carried out, including a full system diagnostic, carried out to search for fault codes that could help identify the level of risk the high voltage fault presents. An example of an additional risk is leaking caustic electrolyte such as potassium hydroxide which has potential to cause harm if correct personal protective equipment (PPE) is not used.

Using the correct service information as supplied by the manufacturer - guesswork is not an option

Without the proper service information, it makes it very difficult to do the job properly, this will include diagnostic fault code information, testing procedures, and detailed schematics including components, current direction flow and required torque settings.

The Picture above is of a Generation 2 Toyota Prius where a build-up of corrosion on the pins of the High Voltage battery ECU has caused increased resistance and resulted in a very minor Fire.

Necessary Insurances

There are multiple insurances which should be in place before work can be carried out on your vehicle high high-voltage system these include a mobile works policy if you operate as a mobile service, goods in transit to carry commercial goods including batteries, Public liability and a fully comprehensive motor insurance for when the need to test drive a vehicle arises.

HYBRID REPAIR SERVICE carries Level 4 Institute of the Motor Industry TechSafe certification and has all relevant insurances in place.

Final Note - Having your electric/hybrid battery and associated system faults repaired by a professional is the best advice,

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