Temperature plays a role in the autonomy of an electric car. To take stock, we pass a Renault Megane e-Tech on our test bench.
In order to take stock of fuel consumption under real operating conditions, we have developed Clean Automobile Supertests. The idea: to check the current cars on the same roads and with the same preparation and driving record for each of them to establish a hierarchy and points of comparison.
But the consumption of an electric car and thus its range are very sensitive to various factors and can vary quickly. Mainly because of the outside temperature. We are as aware of this as you are, but our Supertest has its limitations: we cannot test all the cars at the same time and in the same weather conditions.
Renault Megane e-Tech test: consumption, autonomy and measured performance of our super test
Despite our strict protocol, where the air conditioning in particular is always set between 20°C and 22°C and the car is warmed up before testing, deviations can exist. But in what proportions? As long as we have a Renault Megane e-Tech EV60 again, we have decided to put the cover back on our typical loop to discover its summer autonomy and the differences that may exist.
Renault Megane e-Tech range: 335 km in cold weather
Brief summary of the facts. It was the Renault Megane e-Tech that had the honor of opening our Supertest section. More specifically, an EV60 Optimum Charge copy reviewed in early March. We measured the electric compact at an outside temperature of 9°C, air conditioning in auto mode at 20°C.
At the end of a perfectly mixed loop performed in both directions, the compact electric then admitted an average consumption of 17.9 kWh/100km. A value that allows it to offer up to 335 km of autonomy in these conditions with its battery of 60 kWh net capacity.
|Street||expressway||town, village||In total|
|Disadvantages Average A/R (kWh/100km)||16.9||20.5||16.4||17.9|
|Total theoretical autonomy (km)||355||292||365||335|
This new model that we were able to try is almost identical. More precisely, it is a Techno version, but with the same equipment as the Iconic version tested in winter, thanks to the optional packages. The weight difference, which doesn’t even appear on the data sheet, shouldn’t have an impact. It’s also based on the same 20-inch rims shod in the Goodyear EfficientGrip Performance Electric Drive.
Following the same procedure and with the air conditioning set at 20°C, this new Megane has therefore now been driven on the same roads at a temperature of 24°C. That’s 15 °C difference to our first test, and now under optimal conditions. Also note that we chose to drive in the dark hours of the night in order to develop at the lowest point of the temperature curve, but also to avoid the effect of the sun, which could turn on the automatic air conditioning severe test.
Autonomy in summer: 384 km
The differences in consumption were quickly felt in the current weather. At the end of this loop, the summer Mégane recorded an average consumption of 15.6 kWh/100 km, a decrease of 12.85% compared to winter consumption. With the 60 kWh battery, this equates to an average range of 384 km, or 14.63% better than our previous measurement.
Several factors affect range in winter. The first and last is related to the different thermal requirements, be it for passenger comfort, but also in relation to battery cooling. Since the air conditioning is set to the same temperature, only the thermal management of the battery can influence consumption. But the ambient air temperature is ideal for this, which works in its thermally optimal range.
Renault Megane e-Tech test: charging and driving times from our super test
Contrary to all expectations, the difference is least noticeable in the fast lane. But this is where air density can have the biggest impact. Because the air is denser in winter, it takes more energy for the car to move at a given speed. However, according to our findings, which will be the subject of a future topic in our columns, the difference is clearer at 130 km/h than at 110 km/h, the average speed defined for our mixed loop.
Finally, on the loading side, we didn’t see a significant improvement in downtime from 10% to 80%. In the best case, we were able to achieve a curve with almost 4 to 5 kW higher powers with the same load, which at best allows a time saving of one minute: the charging process is increased from 37 to 36 minutes, with still 128 kW peak power up to 15% SoC . Nothing new in the tropics once the car has been driven.
|Street||expressway||town, village||In total|
|Disadvantages Average A/R (kWh/100 km)||14.6||17.9||14.2||15.6|
|Total theoretical autonomy (km)||411||335||423||384|
A gain of 15% autonomy at 15°C more
In winter, if you don’t take precautions about the temperature of the passenger compartment before you hit the road, fuel consumption will explode. And that is especially true on short daily journeys, where the “fixed costs” of heating weigh heavily on consumption. It is accepted that, without special precautions, autonomy can drop by 25% to 30% between the two seasons. The opposite is also true: in the summer, turn on the air conditioning before driving (this is also for the comfort of the user) and make sure to park your car in the shade, otherwise open the windows ajar to ventilate the air. The cost of air conditioning is reduced.
Thanks to the careful preconditioning of the passenger compartment, the difference in autonomy between summer and winter, according to our measurement base and with the Renault Megane e-Tech, is almost 13%. This value is not an exact science (like actually all measurements outside the laboratory) and it is also difficult to establish a rule with a single measurement (we will repeat the exercise with other models), but it makes it possible to establish a first scale .
Why is the range of electric cars reduced in winter?
In short, to find the consumption at colder temperatures, you can multiply the value recorded in summer by 1.15. So, using the same coefficient, you can determine the autonomy in winter by multiplying that in summer by 0.87. Note that for the reverse calculation (from winter to summer) you only need to invert the multiplier coefficients (0.87 for consumption, 1.15 for autonomy).
To shed light on the differences in consumption depending on the temperature, we will not fail to drive the Renault Megane e-Tech again using the same protocol, with even colder temperatures close to 0ºC. See you in January 2023.