One of the most difficult aspects of designing an electric or hybrid car is packaging the batteries. A plastic fuel tank can be blow-moulded into amazing shapes and squeezed into the space under the rear seat.
Batteries, however, are big and square and demand lots of space.
At the Detroit show, I noticed that back-up battery for VW’s hybrid concept coupe swallowed up a considerable chunk of the otherwise giant boot.
The Mini E, of course, loses its rear seats in an attempt to squeeze in enough battery power to propel the car a claimed 120 miles.
However, Detroit was also host to an intriguing cut-away display of the Nissan Leaf electric car, which shows the importance of a bespoke engineering if you are trying to build a viable battery-only passenger car.
From the right handside, the Leaf’s floorpan looks completely conventional. Which is not altogether surprising as the Leaf is substantially based on the Golf-sized Nissan Tiida.
The left side of the display, though, shows the cleverness of the Leaf layout. Nissan has a battery manufacturing collaboration with NEC and has been able to design these clever, slimline units, 48 of which can be packaged under the floor pressings.
From what I could see, the only compromise was a reduction in the depth of the rear footwells (though that could be compensated for by raising the rear seat). More importantly, the Leaf retains a full-size boot and five proper seats.
It’s an especially impressive achievement as the VW Concept’s suitcase-size battery was only good for 1.1kWh, whereas the Nissan array measures in at 24kWh.
I can understand why Nissan is being very bullish about the potential of the Leaf, which might yet be built in the UK. I drove a late prototype last year in Japan and was hugely impressed by its refinement and pace.
Although Nissan has clearly solved one half of the battery car dilemma, there’s still a way to go on reducing the considerable cost of manufacturing Lithium-Ion batteries.