Short charging time, long range – the e-car is getting off to a good start

Date:2019-04-22 Posted by:Sunny View:779

Our mobility is constantly changing. Where this journey takes us will be determined by changes in our lifestyle and increasing awareness for a more sustainable future. It’s clear that the future of our mobility lies in electrification. E-cars produce no emissions. With the help of sustainably generated energy, they are also CO2 neutral in a broader sense. However, at present, few people are prepared to drive an e-car.

The widespread belief is that the cars are too expensive, take too long to charge, and don’t drive far enough. But these scenarios could soon be a thing of the past. Whether it’s a comprehensive charging infrastructure, development of fast charging stations, or the efficiency of the batteries, a number of innovations are on the horizon. It is, among others, the chip industry that is enabling the mobility of the future with new materials and technologies.

Why do so few people drive e-cars?
Ubiquitous: Charging batteries in everyday life

We all do it – and we do it constantly: Charge batteries. In many cases even without knowing what’s actually happening in our gadgets. The modern smartphone now needs charging every day. We place our electric toothbrush on the charging station overnight. As a matter of course, we also charge portable speakers, smart watches and e-bikes. These charging processes fit seamlessly into our everyday lives and offer maximum convenience with minimum effort: plug in, lean back, done. In principle, the charging process for an e-car is just as simple. Nevertheless, many people dread the thought. Why is that?

Charging e-cars – can it be done faster?
Charging a smartphone, toothbrush or e-cars? From a technical aspect, the process is the same. In all cases, electrical energy is stored in chemical form. However, if you look more closely, you see that there are major differences. Mobile phones can do two things at once: charge and work. The e-car doesn’t offer that luxury. It’s not a technical factor but it’s still significant: We find it normal to charge a toothbrush overnight so that it works the next morning for a few minutes. But when it comes to e-cars, most people regard this as unreasonable – although in most cases, the vehicle is not used for 23 hours a day.

Motorists have become used to driving long distances with their vehicle whenever they want or have to. But with e-cars, this is exactly what appears to be impossible. Yet times have changed! Thanks to technical innovations, we can also experience this freedom with e-cars. Batteries are being developed that enable performance that was previously considered unconceivable. In addition, fast charging stations provide the energy required for huge distances within just a few minutes.

Further development of batteries and charging time

Already a thing of the past: short distances and long charging times
The days when a passenger car equipped with lead batteries could travel no further than 100 kilometers are a distant memory. Just like charging for hours on end. In 1995, Volkswagen built the Golf 3 City Stromer, a car with lead gel batteries that was able to drive up to 55 kilometers. The battery capacity was later increased, which extended the range to 65 kilometers. This may not sound much – but we must remember that a spacious vehicle had to be moved. The charger in the vehicle was designed only for a normal household electric socket which limited the power output. Charging the empty battery cells easily took six to eight hours. A journey of 100 kilometers was possible only with an overnight stay.

These days, e-cars have batteries with much higher capacities. But that’s by no means the end of the story. New discoveries are being made every day.

But the key question remains: How can the battery of an e-car be made more efficient and powerful?

What can batteries do?
Essentially, two parameters of a battery determine how much power a battery set can provide to an engine – and the power with which the battery set can be charged. On the one hand, this is the capacity of the cells. This expresses in ampere-hours (Ah) the maximum charge that can be stored in chemical form. On the other, there is the power density of a battery. This defines how large and heavy a battery must be for a defined power level. The power density is determined by the materials used. The first lead battery was introduced in the middle of the 19th century; today’s lithium ion batteries can hold up to seven times the charge of a lead battery of the same size.

Charging e-cars – now and in the future
The ratio between battery size and charging current is important when charging a battery. For example, since 2016, the BMW i3 has had a battery capacity of 95 Ah. If a 100 Ah battery could be charged continuously with a current of 100 ampere (A), it would theoretically take an hour to fully charge.

To charge a battery with 100 Ah at the current normal voltage of 400 volt (V) in one hour would require an approximate charging power of 40 kilowatts (kW). With up to 50 kW, current DV charging devices already often supply more.

Is that already “fast charging?” Not really. Only roughly the amount of current needed for a range of 200 kilometers can be transferred in one hour.

In the future, everything will revolve around ultra high power chargers. This should allow a battery to be charged with power of up to 350 kW. If it could handle this, a 100 Ah battery would be full in just a few minutes. At present, this high charging power is not supported for any serial vehicle in the world. However, several models have been announced for 2018 that can use the full extent of the new charging technology.

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