High voltage – Big opportunity: Part 1

Ian Gillgrass begins a new series that will try to take some of the fear out of working on EVs, and instead highlight the advantages for garages

Published:  24 December, 2018

Electric vehicle technology means both opportunity for garages and technicians but also necessitates investment, especially in technicians and equipment as businesses have a ‘duty of care’ to look after the technician while servicing and repairing electric vehicles.
    
Who here is old enough to remember when the supposedly deadly airbag was introduced on mainstream production vehicles during the 1990s? Nearly everyone around during this era was nervous of the technology and the highly dangerous components, such as the airbag deployment device, that were encountered by technicians. Today airbag technology is encountered by the workshop technician on a daily basis, and every modern vehicle has some form of supplementary restraint system (SRS) fitted to the vehicle. The dangers first feared by the technician are now treated as part of the daily routine. It will probably be a similar scenario as more and more high voltage electric vehicles are seen both on the road and in vehicle workshops for service and repair around the UK.
    
Treat the vehicle technology with care, educate the technician, gain confidence with the technology and the fear typically reduces. Most vehicles (hybrid and pure electric) fitted with this high voltage technology are inherently safe, reliable and safe to work on providing a few rules are adhered to such as ‘don’t stick metal objects in places where high voltage exists.’
    
Many of the vehicle manufacturers will highlight the potential dangers by placing various warning signs on the hazardous components that have a risk of electrocution, corrosive, fire and magnetism.

Training
Many of the training providers around the UK are now providing training courses on the technology, most will provide an industry recognised qualification or certification by a recognised awarding organisation such ABC Awards, City & Guilds or The Institute of the Motor Industry (IMI). The Health and Safety Executive (HSE) has developed guidelines for the recovery, repair, and maintenance of these vehicles both for independent workshops and franchised dealership networks which is available to view at http://www.hse.gov.uk/mvr/topics/electric-hybrid.htm
    
The HSE website can also provide some useful information that can supplement the information provided on specific High Voltage Vehicle training/qualification courses. The workshop should have the applicable policies in place and ensure that the necessary risk assessment procedures are in place to prevent injuries and fatalities. They should also inform the applicable insurance organisation(s) that they are working on these types of vehicles.
    
It should be noted as with all the present vehicle technology that the vehicle’s control unit will closely monitor the high voltage system and in nearly all cases of a fault being detected, the vehicle system will store an applicable diagnostic trouble code (DTC) and default to a safe running mode or even shut the high voltage system down, disabling the vehicle. The control unit will also illuminate a malfunction indicator lamp (MIL) to indicate the fault to the driver of the vehicle.

Correct
It is therefore imperative that the vehicle workshop has the correct test equipment to be able to access the vehicle systems necessary to retrieve the information to correctly repair the vehicle. Only with dedicated equipment will a workshop be able to facilitate the diagnosis and repair of the vehicle. This also includes the necessary personal protective equipment (PPE) and necessary dedicated hand tools such as a multimeter, insulation tester, insulated tools and the necessary workshop equipment to both repair the vehicle and warn individuals of the potential risk to the exposure of electrocution through high voltage vehicles (i.e. insulated safety equipment, signs and barriers).
    
Hybrid vehicles have been fitted with high voltage batteries since the late 1990s such as the Honda Insight/Accord or the Toyota Prius (now in its fourth generation). The high voltage technology has been seen for many years, its only over the last few years that we have seen that technology being used more widely on vehicles that our customers drive on a daily basis.

Safety steps
To enable a technician to disable the high voltage system to be able to work near/on the high voltage components they should always follow the vehicle manufacturers repair instructions however this can also be seen as ‘seven steps’ to disable the vehicle’s high voltage system. Step 1 to Step 3 are indicated in this article with the remainder in the next article.

Step 1. Ensure others are aware of the potential high voltage/risk: The technician should ensure that others in their workplace are aware of the potential dangers of a vehicle with high voltage in the workshop. The technician has a duty of care to highlight the potential risks and hazards. The technician should perform this task by highlighting to others of the potential danger, indicating that the vehicles’ high voltage system is either ‘active’ or disabled. This can be achieved by applying warning signs on the vehicle along with their name and contact details such as a mobile phone number. The technician should walk around the vehicle to check to ensure there is no obvious damage, liquids or other risks that could harm others. The technician should at the same time begin/follow a risk assessment identifies the potential hazards (HSE indicate that a business that employs five staff and above needs this to be documented). The technician should place additional signs and barriers to enable the vehicle is cordoned off and ensure that others are protected as far as possible from the risk.

Step 2. Switch off the ignition switch/remove the key from the vehicle (3-5 metres away): Hybrid vehicles typically use a vehicle security system that no longer requires the vehicles key (or key fob) to be inserted into a lock assembly to switch the ‘ignition on’ or make the vehicle ready to drive. Many vehicles now have keyless technology so as long as the key is in the vicinity of the vehicle the vehicle ‘could’ become alive. A simple solution is to remove the key (or key fob) at least three metres from the vehicle so that the vehicle does not recognise the key and there is no fear on the vehicle energy unit (engine or high voltage battery system) becoming live. As an example it has been seen that a technician drains the engine oil on a vehicle during a service and the engine starts, the consequences of such an action can be enormous. This scenario could also occur if the vehicle is fitted with a Stop/Start system that is active.

Step 3. Disconnect the low voltage battery:  Vehicles, at present, will still have a low voltage (12 volt) ancillary battery to operate conventional systems such as driver and passenger control systems i.e. instruments, comfort and audio. The low voltage system will also typically control and monitor the high voltage system. Therefore, if the low voltage battery were to become discharged then the vehicle will display the signs of a flat battery and the technician will have to connect their ‘battery booster’ to the low voltage battery in order to wake up the high voltage system.
    
On NO account should the technician access the high voltage battery to connect any booster/charging equipment. The low voltage battery is typically re-charged with a component called the DC to DC converter. This is normally located near to the invertor/electric motor. Note that a battery (low or high voltage) can only store direct current (DC) and to propel the vehicle requires this DC to be inverted into AC to turn the electric motor through a component referred to as the ‘inverter.’ Late vehicles could be seen as no longer fitted with a low voltage battery, vehicle manufacturers are looking to increase the driving range of the vehicle through weight reduction. A low voltage battery typically weighs around 12Kg. The lithium battery will provide both the low
voltage and the high voltage energy required to energise the vehicle.
    Voltages present in hybrid and electric are significantly higher (up to 650 Volts-DC)) than those used in other vehicles (12/24 Volts DC) we commonly see on the road network. In dry conditions, accidental contact with parts that are live at voltages above 50 Volts DC can be fatal. If wet conditions are encountered, then this voltage can become significantly reduced. These vehicles remain inherently safe but as vehicle workshops can be high risk the workshop should always have a trained/qualified first aid person on site. High voltage will also apply to the various equipment that has been used for many years in this environment.
    
The high voltage output is controlled by the low voltage system with the use of ‘contactors’ or large relays. These relays can be seen as large mechanical switches and due to the large currents, that pass through the contacts can be prone to faults such as welding closed. The vehicle low voltage system will typically check the function of these relays during the start-up procedure and if a fault is detected the system will normally produce a DTC applicable to the fault.

Further information
Further information on high voltage vehicle components and their operation will be contained in the next of the articles in this series, along with the next steps in the disconnection process. The reading of these articles will increase a technician’s knowledge of high voltage and the various vehicle systems, but a technician should always ensure that they have the ability to work on these vehicle types competently prior to work commencing.

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