How EVs Are Delivering New Packages

Internal combustion engines are heavy, bulky lumps of hardware that have a huge bearing on a car’s design. Whether front- rear- or mid-engined, each layout has advantages and drawbacks that determine a major proportion of a car’s overall appearance.

An electric vehicle (EV) has an equally important piece of hardware: the heavy, bulky battery. However, there’s one key difference: batteries don’t have to be fitted in one concentrated lump. A battery’s cells can be arranged, distributed and connected together in a wide a variety of different forms – this should give EV designers a far wider scope.

Shaped batteries

The electric Morgan EV3 provides a good example of the way that batteries can be adapted to fit an awkward space. Morgan needed to create a battery that would fit under the EV3’s slender, curvaceous nose, while still leaving sufficient space for occupants’ legs. Relatively small cells were chosen to allow the overall battery to be shaped to fit the complex form required, using 1,914 individual cells.

Volvo researched sandwiching battery pouches between carbonfibre layers

The notion of shaped batteries has also been explored by Volvo. Working together with academic research partners, it formed cells into the shape of existing body panels for an experimental S80 saloon, revealed in 2013. Their approach sandwiched thin battery pouches between layers of moulded carbonfibre. Though a far-sighted approach, bodywork batteries are not yet a practical proposition for a real-world vehicle.

Engine replacements

Many of today’s EVs are based on platforms shared with conventional cars, leading to restrictions when packaging the electric hardware. Batteries and motors are often shoehorned into spaces meant for an engine, fuel tank and transmission. As a result, T-shaped batteries, running along a transmission tunnel and spreading out under seats, are common. Front-mounted batteries in engine bays have also been trialled by various manufacturers, while the boxy swappable battery of Renault’s Fluence Z.E was even mounted behind the rear axle of an elongated front-wheel-drive saloon.

Tesla stretched an Elise by two inches to fit the battery where the engine was

Tesla’s original Roadster dropped an oblong box of 6,831 laptop cells into the vacant engine bay of a stretched Lotus Elise chassis. The Roadster’s electric motor took the place of the rear axle, with power electronics positioned immediately above, leaving space for a narrow boot at the very back. As a result, the Roadster’s package differed very little from its gasoline cousin, offering its occupants exactly what it resembled – an Elise with an alternative power unit.

Skateboards

Tesla’s first purpose-designed EV employed a very different layout, with the Model S adopting a ‘skateboard’ format. Thousands of cylindrical cells – 5,376 in the base 60kWh pack and proportionally more in the bigger capacity editions – are clustered into flat modules, forming a broad expanse between the axles.

The lithium-ion cells Tesla uses are 70mm long, each standing upright across the floor. As a result, the battery structure is not particularly deep – nobody would climb into a Model S and ask why the cabin floor is so high off the ground.

For their first fully bespoke model, Tesla laid the batteries flat in the floor

Keeping the weight of the battery low to the ground is beneficial from a handling perspective, and with motors and power electronics also positioned at axle height, Tesla’s chassis has created some striking packaging opportunities. The Model S debuted with an unexpectedly large front trunk (or “frunk”) as well as a big boot capable of housing a rear-facing third row of seats. While the Model S’s fastback tailgate left the rearmost seating short of headroom, a deep footwell provided plenty of legroom, due to the lack of a big silencer.

The result is a car with very few packaging restrictions. The shape, created by Franz von Holzhausen and his team, doesn’t shout this out, however; the Model S was deliberately made conservative in outline, designed not to alienate buyers accustomed to conventional cars in the same price bracket.

The Model X and Model 3 have followed in much the same cautious tyre tracks, aside from the dramatic indulgence of falcon-wing doors on the X.

BMW LifeDrive marries a carbon monocoque with a battery skateboard

BMW likewise adopted a skateboard layout for its i3 electric city car, creating a ‘LifeDrive’ modular approach with the carbon-fibre Life frame of the cabin sitting atop the alloy Drive module containing the battery, motor, suspension and, in the case of the range-extender edition, a small rear-mounted motorcycle engine.

Catering for an add-on engine left the i3 short of boot space (the engine void was not, alas, liberated for luggage in the pure EV version), but the remainder of the cabin demonstrated the benefits of the skateboard approach. The i3 provided 3-Series interior dimensions within a Polo-sized footprint.

Production platforms

Skateboard-like platforms will underpin many of the next wave of EVs. Volkswagen has already shown a number of concepts based on ‘MEB’, its modular electric platform, including the ID hatchback and ID Buzz minibus, as well as the ID Crozz and Skoda Vision E crossovers. All adopt a Tesla-like layout with floor-mounted batteries and hub-height motors.

Porsche made two large gaps in the Mission E’s battery for greater leg space

Audi’s larger ‘e-tron’ SUV and crossover will use a similar format while sharing components with the Porsche Mission E sedan. The Porsche highlights the flexibility of EV design by cutting out two sections of its floor-mounted battery, yielding sufficient rear legroom within the Mission E’s low-slung, four-seat form.

The upcoming Lucid Air sedan applies exactly the same trick to release space in its opulent rear cabin, while double-stacking cells under the front centre console.

Concepts and the future

Once all the drive components of a vehicle have been packaged into a low-slung module, designers gain huge freedom over the body on top. Front and rear overhangs can be tweaked more easily, for example, when they don’t house essential pieces of hardware.

GM Hy-Wire promised a fuel cell skateboard with interchangeable bodies

While the skateboard layout is now reaching production cars and will soon become increasingly commonplace, the idea has been explored all century long through concept cars. Here are some standout examples:

Venturi Eclectic (2007)

This upright gazebo on wheels also employed a roof-mounted solar panel and even its own compact wind turbine to generate as much of its own electricity as possible. Its top speed of just 31mph meant that aerodynamics were not of any serious concern, hence the focus on visibility and space.

Dodge ZEO concept (2008)

Sitting low at a mere 51 inches (1295mm) high overall, the sleek four-door compact concept very much operated at the other end of the skateboard scale, its 200kW (268bhp) single rear motor putting it firmly into performance car territory.

Nissan Pivo (2005)

Concept vehicles have also explored the potential for deleting further mechanical constraints via drive-by-wire controls. Memorably, Nissan’s Pivo and Pivo 2 concepts in 2005 and ’07 mounted a spherical, rotating passenger pod on top of a flat drive module.

GM Autonomy (2002) and Hy-Wire (2003)

In 2002 and 2003, GM showed a pair of concepts called Autonomy (see top image) and Hy-Wire, pioneering the skateboard approach with a hydrogen fuel-cell powertrain, hub-mounted motors and full drive-by-wire facilities.

While the Autonomy featured a low, shrink-wrapped supercar body, the Hy-Wire was a monoform four-seater that better emphasised the layout. Glazing applied to the Hy-Wire’s nose and tail created an airy cabin, highlighting the absence of mechanical interruptions.

BMW Mini Vision Next 100 (2016)

Mini’s more recent Next 100 concept of 2016 echoed the ideas seen in the earlier Hy-Wire, featuring a similar glazed nose enabled by its battery-powered flat chassis.

Volkswagen Group Sedric (2017)

VW’s Sedric concept, meanwhile, highlights how an EV powertrain combined with fully autonomous technology can yield a vehicle where almost the entire footprint translates into useful interior space.

ItalDesign/Airbus Pop-Up

The Sedric is by no means the most ambitious concept to ride on a skateboard, however. That prize belongs to the ItalDesign/Airbus Pop-Up shown in Geneva this year, designed to unplug from its earthbound battery and take to the skies.