I have never been able to guess the future, or I would have won the lottery by now, but when I was the only technician on a recent hybrid and electric training course, I thought I might have got involved at the right time…
I don’t think anyone could have failed to notice the growing number of electric or hybrid vehicles on the roads. Sales of alternatively fuelled vehicles have risen month-on-month for a while now, even before ‘Diesel’ became a dirty word, and electric charging points are springing up all over the place. The IMI is currently lobbying the government to push for technicians who work on alternative fuelled vehicles to be licensed because these vehicles are entering workshops at an increasing pace and there are potential dangers involved in working around these systems. I think that we should carry a licence to work on all types of vehicles, but that is another argument!
Hybrid vehicles are not the new kid on the block; the Toyota Prius, which has an electric motor to assist the engine, has been available for 17 years now. A few variations of drivetrain design have been made by various manufacturers, but here I will focus on a pure EV and a PHEV (Plug-in Hybrid Electric Vehicle) to give you an idea of the technological advances these vehicles have on-board.
THE NISSAN LEAF
My company car of choice is a Nissan Leaf. The Leaf has been on sale since 2011 and is the most popular, mass built EV in the country. It has no internal combustion engine at all, having only an 80kW electric motor driving the front wheels, which is powered by a large battery pack. The last thing you should be thinking is milk float! These batteries are made-up of 98 individual cells, each holding nearly 4V, approximately 400V in total. Dangerous stuff if not treated with respect.
The high voltage battery cabling, which carries DC voltage from the battery to the inverter unit on top of the motor, is protected by bright orange covers making it easy to spot, this is true of the majority of EV, PHEV and hybrid vehicles. The drive motor is DC and an inverter sits neatly on top of it. The ancillaries, lights, wipers, ECUs etc. are all 12V, as we are used to. The 12V is created by a DC-DC converter, in place of an alternator, there are no drive belts on a Leaf.
The motor assembly is cooled by a traditional coolant system, with an electric water pump circulating the coolant around the drive motor and through a radiator, but not enough heat is generated for cabin heating. This is dealt with via an electric heater, so defrosting is very quick!
THE LEAF HAS A 80KW MOTOR AND IS POWERED BY A 24 OR 30 KWH BATTERY. SINCE IT IS 100% ELECTRIC IT DRIVES COMPLETELY SILENTLY.
Prices start from £16,680, however, entry level Flex models do not include the battery in the vehicle price, a separate and additional battery hire agreement is required. All Leaf OTR prices include a £4,500 government Plug-in car grant.
What’s the range?
Nissan lab tests report a range of up to 124 miles for the 24kWh model and up to 155 miles for the 30kWh model. A meter on the dash provides telemetry data at a glance.
Setting a moderate cabin temperature, pre-heating or pre-cooling the cabin while it’s still charging, will save more of the battery for the road. Driving at constant speeds, minimising rapid acceleration and using ECO or B Mode will also preserve charge.
Activating this limits the motor’s output, cuts back on the air con and slightly increases regenerative braking.
This gives more aggressive regenerative braking, charging the battery back-up using recovered energy from the brakes.
CHARGING THE VEHICLE
Rapid Charger, 30 minutes. Plug into a rapid charger to reach up to 80% charge in 30 minutes.
Home Charging Unit, from 4 hours. Charge overnight using a 32A home charging unit and reach full charge in approximately seven hours (24kWh) or nine and a half hours (30kWh). An optional 6.6kW on-board charger will reduce this time to four hours for the 24kWh battery, or five and a half hours with the 30kWh.
Plug into the mains, 12-15 hours. Charge anywhere there is a standard wall socket.
AND ONE MORE THING…
Solar-powered radio is here! An optional solar cell spoiler, available on the Tekna, converts sunlight into energy, helping power the air con, the 12-volt outlet and the audio system.
THE MITSUBISHI OUTLANDER
I also have a Mitsubishi Outlander, similarlyto the Leaf it uses electric motors, but as it is four-wheel drive, it has them front and back. It’s a hybrid, so also has a two-litre petrol engine. The Outlander’s battery has the capacity for up to 30 miles of pure electric drive, depending on driving style, but cleverly uses the petrol engine to provide power for the batteries, a bit like an on-board generator, in this mode it is a ‘series hybrid’. It also has the function of a ‘combination hybrid’, which means it uses the engine to power the motors as well as the battery pack.
Both the Leaf and Outlander feature regenerative braking. The drive motors’ magnetic fields are turned into generators when slowing. The kinetic energy generated is transformed into electrical energy by the generator and is then converted into chemical energy by the battery. Any additional required braking force is measured by a sensor on the brake pedal, which will then activate the hydraulic braking system once the electric motor loading is at its maximum.
REGENERATIVE BRAKING & HYBRID OPERATING MODES
Regenerative braking, as the name suggests, is a system to generate energy as a vehicle slows down – in particular, when the brakes are applied. Instead of losing energy as heat from the brake disc and pads, which is what all non- hybrid/electric vehicles do, it is put back into a high voltage battery. In this way, the energy can be used again.
Formula 1 fans will have heard of KERS, or the Kinetic Energy Recovery System. This is a good description of what regenerative braking does, it recovers energy that would have been wasted. See info on the right for the operating modes of a typical hybrid vehicle. Pure electric vehicles are the same but, of course, do not have an internal combustion engine.
Under normal conditions, the motor will immediately start the engine at a speed of 1,000 rpm. When the state of charge of the high-voltage battery module is too low, the temperature is too low, or if there is a failure of the motor system, the IC engine will be cranked by the normal 12V starter.
During acceleration, current from the battery is converted to AC by an inverter and supplied to the drive motor. The motor output is used to supplement the engine output so that power available for acceleration is maximised and fuel consumption reduced.
When the vehicle is cruising, the IC engine drives the motor, which now acts as a generator. The resulting output current is used to charge the battery, but only at a very slow rate.
During deceleration the motor is driven by the wheels such that regeneration takes place. The generated output is used to charge the high-voltage battery. Most hybrids now cut the IC engine completely. During braking a higher amount of regeneration will be allowed. This will increase the deceleration force so the driver will automatically adjust the force on the brake pedal. In this mode, more charge is sent to the battery.
On most stronger hybrids, the engine hardly ever idles as the motor will be used to move the vehicle and start the engine if necessary. Other vehicle functions such as aircon can also be run from the high-voltage battery.
Details taken from Tom Denton’s textbook ‘Electric and Hybrid Vehicles’, available on the Amazon bookstore. Tom is currently compiling Hybrid & EV eLearning content for the IMI’s website, which will be available from September.
THE WORLD’S FIRST PLUG-IN HYBRID SUV USES TWIN ELECTRIC MOTORS AND A HIGHLY EFFICIENT 2.0 LITRE PETROL ENGINE.
All new Outlander PHEV models qualify for an £2,500 government plug-in car grant towards the purchase price. Prices start from £31,749, for the entry level Kotu model.
WHAT’S THE RANGE?
Combined range of around 500 miles and up to 33 miles in EV mode, producing combined emissions of only 41 CO2 g/km.
EV power mode:
Drive on pure electric power with near-silent driving and no exhaust emissions.
Series hybrid mode:
The petrol engine charges the battery while the battery powers the wheels.
Parallel hybrid mode:
The engine takes over for high speed motoring and steep hills.
CHARGING THE VEHICLE
By using the network of charge points throughout the UK. All Outlander PHEVs are supplied with a DC rapid charging socket, which can be used at the many CHAdeMO charging stations across the UK. Rapid charging gives an 80% charge in approximately 25 mins. A dedicated charge point installed at home will charge the PHEV battery flat to full in three hours.
I must admit, as a car lover, that it is a strange experience to accelerate away in a car that makes no noise, but it is something that I got used to very quickly. The acceleration performance from both cars is surprisingly good – one advantage of an electric motor is that it can develop 100% torque instantly. My wife often boasts that the Leaf has surprised more than one performance car driver when she’s pulled away at traffic lights!
Personally, I think that this version of emissions-saving technology is the best.It is very convenient to plug either car into my house and not have to visit a fuel station. Flat to fully charged in the Leaf costs approximately £2 of domestic electric, which will give around an 80-mile range. Considering around 90% of people travel less than 30 miles a day, you can see how these cars will catch on.
This technology will filter through to us in the aftermarket and we must be prepared for it. But like high-pressure diesel, in common rail systems, if it is treated with caution, we undergo the correct training and use safe methods, we will adapt and cope, because that’s what we do in the aftermarket!