This study explains why the range of electric cars is sometimes higher in the north

A new study based on data from several thousand Tesla Model Ys shows that batteries in electric cars that are in “colder” regions degrade less quickly than those present in warm regions. With, the key, sometimes greater autonomy. We’ll explain all that to you.

We know that electric cars don’t like extreme conditions. Whether cold or hot. We were able to see this last winter with the major comparison of 28 zero-emission models conducted by the Norwegian media Motor.no, carried out in negative temperatures. Result: it was the Tesla Model S that did the best with a range remaining above 500 km, but with a degradation in range of 16% compared to the announced WLTP cycle. Among the poor performers, the Toyota BZ4x lost 35% of autonomy compared to the summer…

And yet, if the autonomy is indeed affected by the cold, it seems that the heat is not very good for the capacity of the batteries and therefore their autonomy in the long term. In any case, this is what the new study published by Recurring Auto in the United States, which studied data from more than 12,500 Tesla vehicles across the Atlantic.

Electric prefers fresh

This company has access to the data of these vehicles (2020 Model Ys) directly via its tracking software. Data using which it then gives an autonomy score to each vehicle tracked which is none other than the percentage of autonomy retained compared to the original one, when purchased new.

Let us remember in this regard that the range of an electric car decreases with its age and the number of kilometers traveled (via the different charge and discharge cycles).

The results were then put into perspective in relation to the geography and climate of the places where the car data was collected. And indeed, the average range score for 2020 Tesla Model Ys tracked by Recurrent Auto is slightly higher for cars used in the northernmost regions of the United States, where temperatures are on average lower than in the most northern regions. more southerly. The map of the United States published in the study speaks for itself.

In detail, we can see that Model Ys that have been subjected to lower temperatures have an autonomy score of 95, which means that they still retain 95% of their original autonomy. For models that live in warmer regions, the average range score drops to 92, or 92% of their original range. However, these are averages, because there is no indication of the mileage and age of the cars concerned.

But be careful, the range of electric cars in cold weather will always be lower than the range in hot weather. In other words, a car stored in a cold northern climate will benefit from better autonomy if it travels to a warmer climate. But it will still have lost less battery capacity than a car stored in a hot climate. And it will therefore have more autonomy, on a similar journey in terms of temperature.

Original autonomy degraded by heat

Why would ambient heat be harmful to the point of further degrading the batteries? Quite simply because it provides additional energy to the battery’s electrochemical reactions, which can accelerate unwanted chemical reactions that cause the battery to age prematurely. And according to the author of the study, the threshold beyond which the battery can degrade would be 30 degrees Celsius.

If the loss of autonomy in hot weather is due to degradation of the battery, and therefore irreversible, that in cold weather is temporary and due to the fact that the battery is put to greater use for heating the battery and the passenger compartment. But the absence of unwanted chemical reactions means that battery capacity (expressed in kWh) is not permanently lost.

The author of this study obviously tempers things by explaining that these are indeed averages, and that certain vehicles in hot regions obtained results similar to those in colder regions, because they were undoubtedly protected from the sun.

Furthermore, there are some tips to follow precisely to avoid degrading your battery in the hottest regions: protect it from the sun by parking it in the shade, and ideally, if it remains in the sun, it is better to leave it with a half-charged battery than a full battery. Furthermore, LFP batteries are more resistant to high temperatures.

Batteries that are deteriorating, but Tesla reassures!

Beyond these temperature considerations, inevitably, we know that batteries degrade over time. And the study talks in particular about what is called calendar degradation of the battery, which can be explained by chemical reasons: the battery cells degrade, and retain less energy over the years. And then there is the degradation linked to the number of cycles (complete recharge) of the battery.

However, there is no need to be afraid. Last April, Tesla published a report on the longevity of its batteries which is intended to be rather reassuring. A graph showed that the batteries of Model S and Model X lose on average 12% of autonomy after 200,000 miles, or 321,800 km.