Updated: 03 Feb 2010

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Introduction

We look at the latest advances in electric-car technology.

Car companies are spending multi-millions developing electric cars, trying to future-proof their industry and respond to market demand for non-polluting vehicles. Several approaches are being tried - battery-electric, hybrid, plug-in hybrid and hydrogen fuel cell - although few are likely to be available here in the short term.

We look at vehicles that are using these new electric technologies, and take the Mitsubishi MiEV full-electric car for a spin to see how it handles.

Battery-electric

Examples: GM EV1, Tesla roadster and saloon, Nissan Leaf, Misubishi MiEV

The godfather of the modern electric vehicle was the General Motors EV1, the first electric car from a major manufacturer.

The EV1 wasn’t based on an existing vehicle and was produced in limited quantities (1117 of them) between 1996 and 1999. Customers, although they could only lease the vehicles, loved them – but the project was dogged by politics. Eventually General Motors recalled the vehicles and crushed all but a few. The Chevrolet Volt hybrid (more on that below) is the spiritual successor to the EV1.

Electric motors are highly efficient and provide more than enough grunt – the problem is getting enough power to them. Battery-electric vehicles have a rechargeable battery pack that powers an electric-drive motor. There’s no petrol or diesel engine. Recharging is generally done from a standard power socket (which takes several hours) or sometimes from a high-current quick-charge unit. If battery-electric cars become commonplace then recharge stations could possibly be fitted to car parks and parking meters.

Petrol is 77 times more energy dense than the latest lithium-ion batteries – so battery vehicles have a way to go before they can match the range of a petrol or diesel vehicle. Even the latest batteries still leave the vehicle heavy, with limited range and long recharging times. Currently, you can have a high-performance battery-powered vehicle with low range, or a longer-range vehicle with low performance. Only the Tesla roadster comes close to having both (more on that below, too).

Mitsubishi MiEV test drive

We recently put all this theory into practice and “test drove” a Mitsubishi MiEV full-electric car. It’s based on the Mitsubishi iCar, with a lithium-ion battery pack providing the sole power for the car – there’s no petrol engine back-up as is the case with hybrid vehicles.

Visually there’s nothing to distinguish a MiEV from a standard iCar – outside or in. The fuel filler flap opens to reveal a socket for the charging lead, which plugs into a standard  household socket. Charging with the standard built-in charger takes seven hours. An external 30-minute charger is also available, but to use that you need access to a 3-phase electrical supply.

Our verdict
The MiEV is like any other car: you turn the key, put the “transmission” in drive and press the accelerator. But there are noticeable differences. The first is the lack of noise. Electric motors make very little noise – none when stationary and just a slight whining when working. The spirited performance is also noticeable: the MiEV can easily out-accelerate its petrol equivalent.

The downsides are range and cost. The MiEV is only suitable as a city or commuter vehicle. Its range is about 160km – but this varies with driving style, just as it does with a petrol car.

Cost is the biggest killer. Our test model was an engineering prototype: production models could be available in very limited numbers later this year – prices are yet to be announced.

Other battery-electric vehicles

Nissan has also got into the act, with the all-electric Nissan Leaf. This 5-door hatchback is based on the existing Nissan Tiida but is powered solely by an 80kW electric motor that’s fed by a lithium-ion battery pack. Its range is around 160km. The Leaf is due to go on sale (overseas) late in 2010.

In range and performance, the Tesla roadster is the nearest all-electric equivalent to a petrol vehicle. Production of the Tesla roadster – which is based on the lightweight Lotus Elise sports car – began in 2008. The battery pack consists of 6831 standard laptop computer lithium-ion cells, giving the Tesla a seriously quick 0-97km/h acceleration time of 3.7 seconds and a range of 393 km. More than 700 Tesla roadsters have been produced. Their base price in the US is US$109,000.

Tesla Motors has also announced a Model S all-electric saloon will start production in 2011.

Hybrid and plug-in hybrid

Examples: Toyota Prius and Honda Civic hybrids, Chevrolet Volt

In a hybrid vehicle, a smaller-than-normal petrol engine and a battery-powered electric motor power the car. The electric motor assists the petrol engine when required. It also acts as a generator when the car is going down hill or decelerating: it captures energy that would otherwise be wasted on heating the brakes and uses this to recharge the battery. And because the electric motor provides reserve power, the petrol engine can be tuned for economy rather than outright power.

When a hybrid car goes down a hill or comes to a halt, the petrol engine stops – which saves fuel. (Hybrid vehicles save most fuel when used for stop-start city and commuter driving, rather than long-distance motorway cruising.)

A further development is the plug-in hybrid. Here a slightly larger battery can be recharged through a mains power outlet or by the moving vehicle. This means the first battery charge of the day (possibly enough to power the vehicle for a daily commute) can be supplied from the electricity mains. If the battery charge gets low, the petrol engine kicks in.

The vehicles

Now on its third generation, the Toyota Prius is the world’s most successful hybrid vehicle. Power for the latest version comes from a 1.8L petrol engine and a 60kW electric motor supplied from a nickel-metal-hydride battery pack. Toyota has announced its intention of producing a plug-in version equipped with lithium-ion batteries.

The Prius doesn’t have it all its own way: Honda is challenging with its Civic and Insight hybrids. Now in its second generation, the Honda hybrid system is simpler mechanically than Toyota’s and so it’s cheaper to make. The electric motor isn’t as powerful as the Toyota version – so the car doesn’t save quite as much fuel.

The Chevrolet Volt keeps alive the legacy of General Motors’ EV1. This plug-in hybrid prototype seems to have survived General Motors’ financial problems and its US launch is expected in late 2010.

Unlike the Toyota and Honda hybrids, the Volt is always solely driven by its 111kW electric motor; its petrol engine is connected only to an electric generator. The lithium-ion battery pack can be recharged from mains power and gives the car a battery-only range of around 60km. From then on, the petrol motor generates electricity to power the electric motor and recharge the battery. The battery-only range is sufficient for most daily commutes.

Hydrogen fuel cells

Example: Honda Clarity

Hydrogen fuel cells have been around for decades – but they haven’t yet made it to consumer products because of cost. They directly generate electricity from a chemical reaction without any moving parts. The fuel cell generates electricity to power an electric motor, which drives the vehicle. Refuelling is from a special filling station.

Honda has taken the lead here through its FCX Clarity. Still in limited production, the Clarity is available only in Los Angeles (where there are suitable hydrogen filling stations).

It’s powered by a 100kW electric motor fed by a hydrogen fuel cell, which converts hydrogen and oxygen from the air into electricity (and water). A supplementary lithium-ion battery pack captures braking energy for reuse – just like a hybrid vehicle does.

The Clarity is a full-size car, about the size of a Honda Accord and with similar performance and range. It has 5-minute refuelling. Honda says it could start mass-producing hydrogen-fuel-cell vehicles by about 2020.

 

Report by Bill Whitley.