Electric vehicle consumption data is underestimated by manufacturers

Original author: Peter Kellerhoff
Двухлетнее исследование Института транспорта Технического университета Дании (Danmarks Tekniske Universitet) показало, что расход электроэнергии электромобилями при движении выше заявляемого производителями почти на 50%.

Проведенное исследование под названием «Harnessing Big Data for Estimating the Energy Consumption and Driving Range of Electric Vehicles» ("Применение Big Data для определения энергопотребления и запаса хода электрических транспортных средств", ссылка на статью по исследованию (англ.)) had a wide coverage: 741 drivers tested more than two years 200 cars of the brands Citroën C-Zero, Mitsubishi i-MiEV and Peugeot iOn on the roads of Denmark. Each vehicle was handed over to Danish residents for a period of three to six months. Then, GPS and power consumption data for charging were jointly analyzed.

The results showed instead of the declared consumption by manufacturers of 125 Wh / km, actual consumption of 183 Wh / km. These data were obtained from the results of a little more than 2.3 million km. The excess was 46.4%.

According to one of the engineers who conducted the tests: “The Citroën C-Zero battery capacity of 16 kWh means an average range of 87 km. This is much less than the manufacturer’s declared 130 or 150 km, which are achieved under the terms of the new European driving cycle. " (New European driving cycle on Wikipedia )

Thus, there is a significant difference between the real and declared characteristics, as in the case of cars with internal combustion engines. Only a quarter of the trips showed a consumption lower or at the level declared 125 Wh / km. In other trips, the consumption, of course, was higher, sometimes significantly (in some trips it reached 400 Wh / km).

During the study, important results were also obtained for planning city trips and shopping for electric vehicles. The preferred leisurely movement on an electric car at a speed of 30 km / h was not optimal in terms of range. The largest reserve and, therefore, the most economical mode was the movement at an average speed of 52 km / h. It is also important - with a decrease in speed below 30 km / h, energy consumption per kilometer increases exponentially.
Unlike cars with internal combustion engines, the increase in consumption at a speed is relatively small. So, consumption at an average speed of 25 km / h is identical to consumption at 100 km / h [ here, by "consumption" is meant ECR - energy consumption rate - idiv].

For drivers, the following is important - slower does not mean more economical and further. This is an important point for those responsible for planning urban development, who, if they want to reduce CO2 emissions in city centers, advocate a speed of no more than 30 km / h in the same centers.

Another result of the study was, according to Carlo Prato of the Institute of Transport: “People want to charge the car, although there is still at least half the charge. This definitely indicates a fear of being on the road without a charge. ”

On average, each driver carried out 3.4 trips per day, almost half of which were shorter than 5 km [ this value, according to the authors of the study, is due to the small size of the Danish communities and distrust of electric vehicles-idiv]. Only one percent of trips were longer than 50 km. Also, temperature played an important role: in the warm season, the average consumption was 168 Wh / km, in the cold - 225 Wh / km (almost a third higher). According to tests, the smallest consumption was achieved at a temperature of 14 ° C.

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