Training special analysis – Pro-Moto’s Hybrid/EV Level 2 & 3

Whether you are a Hybrid/EV ‘liker’ or ‘hater’, Rob Marshall attended the IMI-accredited course in March and argues that it is beneficial not only for technicians’ safety but also for garage management’s duty-of-care obligations. 

Indeed, while there was a degree of scepticism surrounding the ownership experience of hybrids and EVs in the classroom, everybody concurred that they will be required to service, diagnose and repair them now, if not in the very near future. Even experienced delegates from EV service centres and battery suppliers agreed that they were looking to soak-up fresh insights about the functions and diagnoses of both hybrid and EV systems, as well as learning new safe working practices. Their admissions that the course was beneficial to them proves its worth. 

Despite around 65% of the course being ‘classroom’ based, attendees are not lectured. Active debate, sharing experiences, humour and asking questions is actively encouraged. Starting with the theory of Hybrid vehicle layouts, from looking at the differences between parallel, series, power-split and dual types, with practical examples of each design, through to detailed descriptions of the separate low and high voltage systems, provided the basic knowledge. Naturally, when discussing how the high voltage system works, a degree of elementary electrical knowledge is required but this did not extend beyond Ohms’ Law and the difference between AC/ DC. Yet, when technicians needed to brush-up on their basic knowledge, they felt comfortable enough to ask. At no point did anyone comment that they felt trapped in a two-days-long physics lesson. 

WITH SAFETY AT ITS CORE

Aside from the practical experience of testing the high voltage Hybrid/EV electrical system and making it safe, you are also briefed on the test procedures required every time you use the required safety equipment.

As 40-50 volts is sufficient to overcome human skin’s resistance with 0.08 amps being sufficient to cause cardiac arrest, it is unsurprising that many technicians treat hybrid/EVs with trepidation, considering the typical 100 to 600 operating voltages, and up to 150 DC currents being expected within the high voltage system. While the course emphasises these risks continually, it succeeds in making attendees more confident without encouraging carelessness. Detailed explanations impart knowledge about how a car powers itself down, followed by practical demonstrations of how to check that the high voltage circuit is safe and, if not, how to make it so, in order for subsequent diagnosis and repairs to be conducted safely. 

Explanations about why capacitors are needed to supplement the high voltage battery in high demand situations, such as during move-off and rapid acceleration conditions, highlighted the different discharging procedures. On the third-generation Toyota Prius demonstration car, the capacitors discharge within ten seconds via the motor/generator windings but technicians need to be aware that this can take up to five minutes on some other makes. 

Interestingly, the course supplements model-specific data that workshops can glean, because not all manufacturer procedures include crucial health and safety material. The importance of using, checking and renewing Class Zero rated gloves that offer a minimum of 1,000 volts protection, choosing, testing and handling multimeters (not forgetting the leads) of at least Category Three insulation, plus using insulated tools that comply with IEC/EN 60900 are all emphasised. While
the technician working on a hybrid/EV is responsible for the health and safety aspects, the course also gives the knowledge about how to protect other people in the workshop from potential harm. This includes how to use emergency safety equipment, as well as how to deal with potential chemical and fire hazards that the different battery types present, as well as being respectful of the strong magnetic fields within the motor/generator unit. Aside from technicians, workshop managers and garage owners would find attending the course useful as well, especially with due regard to Corporate Manslaughter as a result of breached duty-of-care. 

PRACTICAL EXAMPLES

The second day of the course sees more advanced operations, from taking voltage readings at various points of the high voltage battery pack, to removing it completely and safely from the car.

Unlike the major components of a conventional ICE car, certain parts of a high voltage system can be sited in various locations. Therefore, the high voltage battery control unit, the AC/DC semiconductor inverter, the DC-DC converter and capacitors are not positioned in the same places. On the 2009 demo Prius, they are situated within the main inverter, identified by orange DC cables entering it
and three-phase AC cables exiting to the motor/generator and air conditioning compressor. Everybody had an opportunity to use the safety equipment and go through the theoretical seven-step safety procedure, by removing the invertor’s access cover and checking the DC connections for voltage, to determine whether, or not, the vehicle was safe. 

Several written exercises take place, with a final online assessment (more of a quiz than a formal examination) ending the course. Nobody failed to attain the 60% required pass rate, during our visit.

The following day, everybody refreshed the practical skills of the previous day, prior to learning how to test-probe the high voltage battery, prior to disconnecting it safely from the car and removing the entire unit and placing it on a work bench. Naturally, with the emphasis firmly on safety, everybody learns how to remove the battery covers and make visual inspections of the air cooling ducts, terminals and wiring for corrosion, as well as measuring the voltages both on the battery itself and on its relays. Considering that most attendees started the course with virtually zero confidence with working on high voltage systems, the fact that they could perform such a major operation safely and with confidence by the end, highlights its effectiveness and value. 

GARAGE OWNER GIVES HIS VERDICT 

“I previously took a Level Two Hybrid/EV course with Eliot and enrolled on this combined Level 2 and 3 module as a pathway to Level 4’s more advanced problem-solving techniques. Eliot has a knack of engaging with everyone present, regardless of ability and I cannot recommend the course more highly. Yet, when deciding on training, a variety of factors influence the decision. The costs of travel, subsistence and being away from the workshop have to be weighed against the value of the knowledge gained. With Eliot taking his show on the road (and Matt of Cleevely Electric Vehicles providing a venue fairly local to me) my decision was easy to make.” 

Peter Greenow, Director, Dinedor Cross Garage, Herefordshire. 

COSTS

On-site training: