Why are most electric cars only suitable for shorter distances?
Only very few electric cars achieve ranges of more than 200 kilometers, otherwise, the battery would be too large and heavy, because the energy density of rechargeable batteries is lower than that of petrol, for example.
One kilogram of petrol (around 1.33 liters) contains almost 12,000 watt-hours (Wh) of energy. Lithium-ion batteries in cars today have an energy density of no more than 140 Wh/kg. Since a typical electric car consumes about 20,000 Wh per 100 kilometers, it must carry about 150 kilograms of batteries.
What makes the battery so expensive?
The battery is the most expensive part of the electric car. In the E-Smart, for example, only the battery system costs an estimated 6,000 to 7,000 euros. That’s because battery modules consisting of several cells are connected together to achieve energy quantities of 15 to 30 kWh, which is usually required by an electric car. This means that a single battery can contain several hundred small individual modules.
Above all, however, demand affects the price: lithium-ion batteries suitable for use in cars cost a good 500 euros per kWh today. With large-scale production, the costs could be reduced to 130 to 160 euros in the future.
How long does an e-car battery last?
Experts estimate the service life to be ten years and more – provided that the battery is always kept at a good temperature. This means that heat generated during charging can permanently clog the battery. For that reason, it should be kept at a temperature of 25 to 45 degrees Celsius. In addition, the frequency and, above all, the intensity of charging and discharging have a decisive influence on the battery’s durability.
This is why batteries in electric vehicles are only discharged to around 20 percent of their capacity. This means that several thousand charging and discharging cycles are possible before performance drops significantly. The manufacturers guarantee mileages of between 100,000 and 160,000 kilometers. But real long-term experience is lacking.
How high is the fire risk?
In mid-2011, a Chevrolet Volt caught fire after a crash test; a year later, a Chinese e-taxi went up in flames. It’s individual cases like these that fuel discussions about the fire risk of lithium-ion batteries. Accident researchers are reassuring, however: In principle, drivers of series-produced electric cars are not exposed to higher risks in the event of a collision than in a comparable vehicle with a combustion engine.
Even the recent battery fires at Boeing’s “Dreamliner” cannot automatically be used to derive safety risks for electric cars: The aviation company uses lithium cobalt dioxide batteries – one of the most flammable lithium-ion variants. Less explosive materials are used in cars.
How much does battery production pollute the environment?
Assuming a service life of 150,000 kilometers, modern batteries account for a maximum of 15 percent of the total environmental impact caused by the manufacture, operation and disposal of electric cars, according to the results of a Swiss study.
According to material testers, regular charging has the greatest impact on the life cycle assessment. If, for example, a common European electricity mix is used to charge the car, the environmental impact is much greater than the battery itself.
Through recycling and dual-use, however, batteries could become more environmentally friendly in the future, since a large proportion of the raw materials can be recovered. In addition, cells that are already too weak for cars can be used for years as stationary energy storage devices, for example in homes with photovoltaic systems.