Will electric cars protect you and your family in the event of an accident?

By Gavin Conway on July 21, 2011 5:22 PM

The benchmark for pure electric car safety has recently been set by the Nissan LEAF, which earned the maximum possible score of five stars in European crash testing (Euro NCAP).

The LEAF also scored the top rating in American crash tests - it shared that best possible result with the Chevrolet Volt extended range electric car, which goes on sale here in the UK in 2012 alongside the virtually identical Vauxhall Ampera. And we would expect that the Volt/Ampera will do very well when put through Euro NCAP testing later this year.

As you’d expect, the LEAF and Ampera come with all of the safety kit you’d expect of any car in the class, regardless of what’s powering the wheels. That includes ABS brakes, electronic stability control, pre-tensioning seatbelts, front, side and curtain airbags and even ‘noise’ generators to warn pedestrians when the car is travelling at low speed.

There is good reason to focus on the Ampera and LEAF safety performance. Over the next couple of years there will be many more conventionally-sized pure electric cars coming to market from manufacturers such as Ford, Renault, BMW and Audi. And to be competitive with benchmark cars such as the LEAF and Ampera, they’ll have to match their excellent crash test performance. In that sense, the safety of future electric cars is likely to be at least on a par with their petrol/diesel class equivalents.

Other pure electric cars that have been put through Euro NCAP include the Citroen C-Zero and Peugeot Ion, both based on their sibling Mitsubishi i-MiEV. Each of them scored four out of five stars, a result that can be partly attributed to their relatively diminutive size compared with top-scoring Ampera and LEAF.

Then there are electric vehicles classified as ‘quadricycles’. The safety regulations applied to these are far less rigorous than those of more conventional cars like the cars mentioned above. Simply put, a tiny electric quadricycle such as the well-known REVA G-Wiz is far less safe than something like the LEAF, both because of its tiny size and comparative lack of conventional passive and active safety aids.

Another common concern about electric cars is the risk of battery fires, a risk perception that was heightened a few years back when lithium ion batteries in a number of laptops and mobile phones caught fire.

This risk relates to the high energy density of the batteries, with a huge amount of energy packed into a relatively small package. That makes lithium batteries a great candidate for powering electric cars, but also carries the risk of overheating. To prevent that from happening, manufacturers are using all sorts of precautionary technology, such as fuses and circuit breakers that will disconnect the batteries when sensors detect a collision is about to happen.

Cooling the batteries is important, too, as the hotter they are the bigger the explosion risk. Tesla, for example, uses radiator-chilled coolant throughout the battery pack to keep the temperature as low as possible while the car is running. By contrast, the current LEAF uses an air-cooling system.

The reinforced battery pack of electric cars are also normally located in the well-protected centre of the car, as far as possible away from the car’s crumple zones to avoid damage in a collision.

At any rate, we believe that the risk of battery fires is tiny, and driving a modern electric car is no more risky than travelling around with 60-litres or so of extremely flammable liquid on board. That’s what most of us with petrol-engine cars do every day.