In winter, the heat pump changes everything (or almost)

The winter cold is the sworn enemy of the electric car. But equipped with a heat pump, the battery car runs longer in freezing temperatures.

Basically, electric cars lose a fifth of their autonomy when mercury drops to zero, according to Recurrent, a company that collects battery performance data. Taking a place in an icy car is not pleasant, but it is by heating the passenger compartment that the battery is plus the most.

However, according to Recurrent, the installation of a heat pump can reduce the loss of autonomy by half. Generally, the heat pump less the battery than the old heating with electrical resistance which equipped the first electric cars. The best, today, only lose 11 % of their autonomy, on average, when it freezes.

“Among electric vehicle drivers, the concern linked to winter cold decreases rapidly,” says Andy Garberson, who directs research at Recurrent.

According to Greg Brannon, director of automotive engineering at AAA (the American CAA-Québec cousin), the heat pump could make the electric car viable in the eyes of many drivers of the regions moderately cold.

In the colder regions, when the temperature drops under -10 ° C, the impact is less, because the heat pump loses its efficiency in very cold.

“It depends on temperatures at home,” says Brannon.

What electric models work best in cold weather?

Army of data in real conditions of 18,000 electric cars in the United States, recurrent measured the lifespan of their batteries at different temperatures. The company classified 20 models according to the loss of autonomy when the mercury is under 0 ° C compared to their performance at around 21 ° C, the ideal temperature.

Some models have a heat pump only in certain versions, or after certain models, such as Tesla from 2021. This change makes a whole difference: the models only equipped with resistance heating lose twice as much autonomy in cold as The new models also equipped with a heat pump, according to Recurrent.

In general, heat pump improves performance in the cold, but not always. Other factors, such as battery design, have improved or reduced the classification of certain models, explains Mr. Garberson.

Consult the Recurrent site and the table of electric models equipped with heat pumps

Why does cold affect electric cars?

It is partly explained by chemistry: the cold slows down the movement of lithium ions inside the battery, which makes it less effective. In addition, the cold air is slightly denser, which increases its resistance for all vehicles, not just electricity.

However, most of the loss of autonomy is attributable to heating. Petrol cars use the residual heat of the engine to heat the cabin, but electric vehicles must draw from the battery.

Three -quarters of the loss of autonomy come from heating, estimates a 2019 AAA study.

The most common type of electric heating is to circulate a lot of electricity in a serpentin which heats up by resistance and gives off its heat in the ambient air. The heat pump, basically, extracts the little existing heat from the outside air and concentrates it in the passenger compartment, a process much less energy -consuming than heating by resistance.

Unfortunately, heat pumps lose great efficiency when the mercury goes down under -9 ° C or -10 ° C, notes Mr. Garberson. At these temperatures, even cars equipped with a heat pump switch to heating by electrical resistance.

In short, heat pump or not, when it is -10 ° C or less, the loss of autonomy is the same.

But otherwise, during the winter days when it is less cold – which is no longer so rare – there is still a notable advantage, concludes Mr. Garberson.

This article was published in the Washington Post.

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