What goes into electric super cars?

Just look at those lines. The 324-kWh battery pack from a BYD bus
shows how deeply unsexy electric conveyances are inside.

WITH reference to Wheels report on ‘Electrifying supercars’, it’s become astonishing to see that they can not only reach speeds of 300 km/h, but the acceleration factor is almost unbelievable. Zero to 200 km/h in 7,1 seconds must impose something like 1,5 to 2G on the occupant(s).

The questions are, what sort of motor or motors are used, kW, amperages, voltages etc. and what type of drive transfer?

Best regards and thanks for an always interesting supplement.

Werner Ehlers,
Mt Michael.

WE are glad you enjoy reading as much as we do compiling the latest trends in transport.

The answers to your questions can fill volumes, but I want to say if you find the tecnology in fast
electric cars fascinating, you may be astounded by what I deem the world’s best new car — the solar-powered Stella Lux.

Built by Dutch students, this four-seat, family saloon has a 15 kWh battery bank that only gets tapped when the car moves faster than 45 km/h, but at slow city speeds the 5,8 m² solar panel, which doubles as the Stella Lux’s roof, captures more power than the car uses.

This is as close to a perpetual motion machine as physics allow.

Its all in the hub

But back to your questions, most electric vehicles (evees) use alternating current, synchronous brushless electric motors, and they come in all sizes — even fitting inside the rims of skateboard wheels.

While Tesla puts these motors on both axles, the trend is towards in-wheel hub motors, whether to propel bicycles or trucks. To my mind, Protean Electric leads the fray with their 75 kW (100 hp) and 1000 Nm (sic) hub motor that has already been extensively tested.

While as strong as a truck engine, Protean’s hub motor weighs only 34 kg and fits into a 18-inch rim. Vector control of the power to each hub ensures precise cornering.

The first patent for a hub wheel motor dates back to 1884, but what will ensure that modern electric cars will not fade like those at the turn of the 19th century are cheaper Watt-hours and sophisticated traction control systems.

Amp it up

As for Amps and voltage, the “fuel tank”, or battery pack of modern evees can contain from hundreds to thousands of the same lithium-ion batteries we use in toys. These 3,6 Volt, 3000 mAh rechargeable batteries has now totally replaced the lead-acid batteries.

Tesla made Panasonic’s batteries the trusted brand, packing over 6 000 of these tiny batteries into the Tesla cars’ battery banks, each cell connected in series with their own little fuses in modules.

Because the battery packs are modular, engineers can pack as many kilo-Watts as space allows.

The 2015 world solar race built by UKZN students had 20kg, or close to 500, of these lit-ion cells in its battery pack, to power a tiny 2kW Mitsuba hub wheel.

The Jaguar Ipace packs a respectable 90kWh, but the Chinese BYD bus comes loaded with 324 kWh and daily runs over 300 km in 35 countries.

Face-peeling fast

Because torque is almost immediate on electric motors, all forms of electric transport — even the BYD bus — have face-peeling acceleration if left uncontrolled.

The fastest evee currently is the 168-kg Grimsel electric race car.

Built in less than a year by engineering students at ETH Zurich and Lucerne University of Applied Sciences and Arts, it last year did the 0-100 km/h run in 1,513 seconds.

The Grimsel used four 37 kW hub motors, putting out a combined 1 700 Nm and 148 kW (an old fashioned 200 hp). This makes the 4s run of the all-electric Jaguar Ipace seem slow. But none of these excite me as much as a family car that uses the sun to make more power than it uses.