In the description of any electric car, you can find such a characteristic as a power reserve. Most often, the abbreviation WLTP or NEDC is next to it, but sometimes EPA is found, and CLTC for Chinese cars. We will look at how the range is measured in Europe, USA, Japan and China.
Often the range of the same electric vehicle differs depending on the rating system. For example, the American EPA test shows that the BMW i7 can travel 493 kilometers on a single charge, and according to WLTP - 610 kilometers.
Which of the data is closer to reality and how is it that different rating systems are so different from each other?
NEDC (New European Driving Cycle)
The European Standardized Driving Cycle NEDC has been developed since the 1980s and became mandatory in 1992. It applied to all passenger cars and light commercial vehicles.
NEDC was used to measure fuel consumption and CO2 emissions, and later to calculate the range of electric vehicles.
- The temperature in the test room was in the range of 20-30°C;
- Distance - about 11 kilometers;
- The cycle time is about 20 minutes, of which two-thirds of the time was simulated driving around the city, and one-third - off-road;
- Average speed - 33 km/h;
- The highest speed was 120 km/h;
- The time and conditions under which the gearshift occurred were determined in advance.
The main disadvantage of the NEDC standard was that the results obtained were far from the actual values of fuel consumption and the amount of harmful emissions observed during operation.
WLTP(World Harmonized Light Vehicle Test Procedure)
Another European standard, WLTP shows results closer to actual operating conditions than NEDC.
The assessment is carried out under the following conditions:
- The temperature in the test room is maintained at 23°C;
- Distance — about 23 km;
- Passage time - 30 minutes;
- The cycle consists of 4 phases (slow, medium, high and extra high);
- Average speed - 47 km/h;
- 13% of the cycle time the vehicle remains stationary;
- The highest speed is 130 km/h;
- The time and conditions under which the gearshift occurs are calculated individually for each car;
- The influence of additional optional equipment is taken into account.
Tests are carried out on a bench with running drums and on public roads. As already mentioned, the car must cover a distance divided into four blocks at different speeds:
- low (up to 60 km/h);
- medium (80 km/h);
- high (100 km/h);
- extra high (130 km/h).
In addition, two tests are carried out - with and without additional equipment turned on. This allows you to provide correct data for models in the basic and maximum configuration.
EPA(US Environmental Protection Agency)
This standard also has its own conditions for testing:
- Distance length — 17.7 km;
- Average speed is 32 km/h;
- The maximum test speed is limited to 96.5 km/h;
- Parameter evaluation is carried out in the laboratory and on public roads;
- Simulation of city driving occurs with frequent stops over 12 km.
When comparing the range rating of electric vehicles by different standards, the EPA results are the lowest.
In Japan, the JC08 valuation standard is applied and was formally adopted in 2010 and finally introduced in October 2011.
- Testing time - 20 minutes;
- The average speed is - 24.4 km / h ;
- The maximum test speed is limited to 81.6 km/h;
- 30% of the time the vehicle is at rest;
- Various start options are taken into account - with a jerk from a place and calm.
CLTC (China Light-Duty Vehicle Test Cycle)
For Chinese electric vehicles, CLTC, a local mileage standard that is very close to NEDC, has become more common. It implies smoother acceleration (0.45 m/s vs 0.53 for WLTP) and low average speed (28.96 km/h vs 46.42 km/h for *WLTP *).
To summarize, none of the above test systems will show the range that a particular electric vehicle will have, since the driving style of all drivers is different.
The result closest to the average will be WLTP. The Japanese JC08 gives more accurate figures for the urban cycle, and the American EPA is the minimum that an electric car owner can definitely count on.
The main problem of all testing systems is the temperature range at which the range of electric vehicles is evaluated. Tests are carried out at the most comfortable temperatures for battery operation around 23C, but in reality, electric vehicles are operated in less than ideal conditions.
For example, WLTP tests take place at 23°C, while in Norway, where electric vehicles are widespread, the average summer temperature ranges 7 to 17°C depending on the region.
When choosing an electric car, remember that the stated range is by no means guaranteed. Air temperature, precipitation, winter tires, terrain, open windows, air conditioning and a stove can cut it in half, maybe even more.