EVs still need a gearbox

LEADING Australian transmission engineer Ric Tamba believes that future electric vehicles should be developed with two-speed rather than one-speed transmissions.

While he concedes that electric car designers have so far chosen to demonstrate the exceptional torque characteristics of electric motors by using only one forward gear, Mr Tamba claims he has proven that having two forward gears will improve acceleration for the same amount of electricity and could also help keep costs down.

“We have done some tests on the (BMW) Mini, comparing the 88kW petrol model to an electric version fitted with an 88kW electric motor,” he said after addressing an AutoCRC technical conference in Melbourne last week.

“With a single-speed transmission, the electric Mini was slower. But when we installed a two-speed gearbox, it was much faster than the petrol model.

“We then installed a 70kW electric motor, and the single-speed version was slower again. When fitted with the two-speed transmission this car was, of course, slower than the 88kW car with two speeds (but) it was still faster than the petrol car.”

Left: Ric Tamba.

Mr Tamba said this meant car-makers could save money by using a smaller electric motor and batteries.

Although the two-speed gearbox would eat up some of the savings, he nevertheless predicted there would be a trend among EV designers towards multispeed automatics and CVTs (continuously variable transmissions).

“We are actually working on a little project for a Chinese manufacturer that wants to take a washing machine motor, put it in a car and put an existing 4-speed auto behind it so he can have a 4-speed EV,” Mr Tamba told the conference.

“They’ll use a cheap little $100 motor basically to get that vehicle up and running – maximum speed 60km/h – but that’s what they are interested in doing. You need to look at the market before deciding what is the best technology to take into it.”