Are electric cars also good for longer distances?

Posted by Christian Pfäffli on

Which factors are important? And what do you have to bear in mind when you decide on a long-distance model?

  • The charging technology is crucial for long-distance capability
  • E-cars are suitable for long-distance journeys if they charge energy for 200 kilometres in 30 minutes
  • Particularly important: The charging strategy of battery management

    Time is a precious commodity. Especially at work, but increasingly also in private life. No wonder, then, that we are always anxious to get to our destination as quickly as possible, even when we are on the road by car. No matter whether it's a business appointment, on the way to the cinema or to a holiday destination.

    At least on long-distance journeys, most electric cars still reach their limits in this respect. The necessity of having to reload several times on the way from Hamburg to Munich, for example, makes travelling a test of patience.

    However, in the meantime, current or already announced models have larger batteries and thus also longer ranges. Also, the fast charging technology of the vehicles is getting better and better. It's just a pity that vehicle manufacturers often provide only vague information on this and sometimes demand a surcharge for the CCS fast-charging socket. This should be standard equipment today.

    Fast charging with up to 350 kilowatts

    In addition to the Tesla models, which for years have been provided with high charging capacities of more than 100 kW on the specially installed superchargers, other car manufacturers are now finally offering vehicles for sale that can handle high charging capacities. High Power Chargers (HPC), for example, enable an energy supply of 150 up to 350 kW thanks to cooled charging cables.

    Cars that can digest so much charging power are the Audi e-Tron, Porsche Taycan and Tesla Model 3, announced are the VW ID.3, the Ford Mach-E and the Polestar 2, which will be on the market in 2020.

    Furthermore, there are more and more models that can charge with more than 70 up to 110 kW, for example, the Mercedes-Benz EQC and the Korean Hyundai Kona Elektro (64 kWh battery) as well as the Kia e-Niro and the e-Soul with the 64 kWh battery. With the Opel Corsa-e, Peugeot e-208 and the Citroën DS E-Tense, the trio of the French PSA group with the announced 100 kW charging capacity is in the starting blocks.

    The battery should feel good

    CSS-Ladestecker
    Made for quick charging: CCS plug ∙ © Daimler

    So we're good? Unfortunately not, because despite all technical progress, fast loading still has its pitfalls. Drivers are constantly observing that their e-cars sometimes charge faster, sometimes less quickly - and even at the same quick-charging station.

    Car manufacturers explain this phenomenon with the control strategy of the battery management system, which determines the actual charging performance. This is because the battery management system has to ensure that the battery is not overly stressed during charging. If it were to be subjected to excessive stress, this could harm its service life - and of course, the manufacturers want to prevent this at all costs.

    Like humans, a battery also has a kind of comfortable temperature and suffers from stress factors. To achieve the ideal charging capacity and thus short charging times, the temperature of the traction battery must always be within the comfort zone during the charging process. If the battery has cooled down in winter, for example, the charging time for quick charging will be considerably longer, as it first has to be brought to temperature.

    Car manufacturers usually specify the charging times for quick charging for up to 80 per cent of the battery capacity. This makes sense because the fuller the battery, the more the charging power is reduced to protect the drive battery.

    ADAC test: Charging curves and ranges

    Since it is important for electric car drivers and prospective buyers to know and understand the rapid charging behaviour of an electric car, the ADAC has measured the charging curves of some vehicles and shows them transparently. The focus here is on the range between 10 and 80 per cent battery charge relevant for quick charging.

    The result: The charging strategies for protecting the battery vary greatly between models from different manufacturers. The Audi e-Tron, for example, charges amazingly constantly in the relevant range with a maximum output of just under 150 kW, resulting in an average charging capacity of 145 kW. In contrast, the Mercedes EQC continuously reduces its charging power from a nominal 110 kW at just under 40 per cent battery level.

    In the power range around 50 kW, the Nissan Leaf also shows a constantly high charge curve, whereas the Renault Zoë starts to reduce power continuously at just under half battery level. Other vehicles, such as the Opel Ampera-e, do not reduce the charging power continuously, but gradually.

    But high charging power alone is not enough - the vehicle's fuel consumption is also important. In the end, the comparison of recharged range per time is of practical relevance for the driver. For example, the Audi e-Tron recharges 113 kilometres of range within the first ten minutes, while the Nissan Leaf recharges only 40 kilometres. If the e-Tron is recharged for half an hour, it can cover 305 kilometres with the charged energy, while the Nissan Leaf covers 124 kilometres. These are huge differences.

    200 kilometres in 30 minutes desired

    To make electric cars comparable in terms of their rapid charging capability, the ADAC will determine both the charging curves and the recharged ranges in the first 30 minutes in all future e-car tests. A definition of long-distance suitability will also be introduced: An electric car can be considered suitable for long-distance use if it has a range of at least 300 kilometres determined by ADAC Ecotest and a rechargeable range of at least 200 kilometres in 30 minutes.

    In practice, this definition means that a car journey requires a pause for charging about every two to three hours. This is a pause interval that should also be observed when travelling with a combustion engine. And in this respect, the travel time with the electric car is kept within comparable limits.

    Conclusion

    Of the vehicles tested to date, the Mercedes EQC and the Audi e-Tron meet the criteria for long-distance suitability. And even if no vehicle was currently available for measuring the charge curves, it can be assumed based on the known data that all Tesla models and the Porsche Taycan are also suitable for long-distance use.

    In principle, it is apparent that, given the appropriate fuel efficiency of the car in question, charging capacities of around 100 kW and above may be sufficient to achieve the defined long-distance capability.

    The other cars investigated to date do not meet the requirement of long-distance suitability. The Opel Ampera-e, the Renault Zoë and the Nissan Leaf feel more comfortable in the regional use scenario. For long-distance use, they should be used only rarely and with an appropriate time buffer. The upcoming ADAC tests will have to show whether cars with a charging capacity of less than 100 kW can be suitable for long distances.

    Tips for e-car drivers

    The better the quick charging function, the more flexible an electric car can be used in everyday life and for longer distances
    • Before purchasing, consider how often a vehicle should be used for routes beyond the vehicle range. The more often, the more important the quality of the quick charge function
    • Always order the fast charging function if it is not included in the standard scope of delivery
    • Always charge the battery only up to 80 per cent when on the move, charging takes a disproportionately long time
    • For longer distances, an e-car should have a range of at least 300 kilometres according to ADAC Ecotest and a range of about 200 kilometres reloaded in 30 minutes
    • To preserve the drive battery, only charge quickly when necessary
    • In cold temperatures, pre-heat the battery or allow for longer charging times

     

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