Earlier examples of the Leaf, built in Japan, had a similar protuberance in the boot. As with the Ford, the bulky rear box was needed to house chunky pieces of high-voltage hardware, responsible for supervising the flow of energy to and from the battery. More recent British-built examples of the Leaf, updated in various ways, benefit from smaller lumps of hardware that have been squeezed under the bonnet, yielding a rear end free of unexpected bulges.
Leaf and Focus boast about the same battery capacity – 23kWh in Ford’s case and 24kWh for the Nissan. Ford’s battery is tucked away under the rear seat and above the rear axle, while the Nissan’s battery is flatter, wider and mounted further forward, running under the front and rear seats as well as beneath the raised rear footwells. When it comes to packing in all the required pieces of hardware, Leaf trumps Focus comprehensively.
Both cars employ a lithium-ion battery chemistry but the Ford package is more sophisticated, with liquid heating and cooling of the pack to help ensure long life and durability. The Leaf’s battery, by contrast, is passively air-cooled, though it’s too early to say if this less complex design will prompt many early failures. In the relatively mild temperatures of the UK, the benefits of active temperature control may well be negligible – or at least that’s the argument put forward by Nissan.