Warwick, England – Using a multi-speed transmission on an electric vehicle (EV) improves its energy efficiency over the single-speed gearbox that most currently use, according to new research by automatic transmission company Antonov.

Comparative studies by the company over eight different drive cycles suggested that the multi-speed transmission typically delivers 10 per cent better cycle efficiency.

“The majority of electric vehicles are currently equipped with a single speed, so there are clear implications for the next generation of electric vehicles,” said David Paul, business development manager at Antonov. “Our analysis shows that with a single-speed gearbox there is significant variation in drive cycle efficiency, whereas a multi-speed transmission tends to be more consistent with better overall cycle efficiency.”

Paul said that there is an inevitable compromise with a single-speed gearbox, particularly in terms of low-speed acceleration, hill climbing and high-speed cruising. “The 10 per cent step change improvement in efficiency can be achieved with just two ratios, but technical compromises remain in other areas,” Paul said. “Three or more ratios are better, delivering additional improvements in performance and refinement as well as efficiency, with each additional ratio providing small incremental gains in cycle efficiency.”

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