Study confirms electric cars lose range in cold weather

A new report by the American Automotive Association confirms that electric cars from a variety of manufacturers lose range in colder weather even when the heating system isn't being used.

A number of Tesla owners and other electric car users in the US recently reported that their vehicles had been experiencing reduced range and other issues in the cold weather that recently hit part of the country. Conflicting reports from various manufacturers and users of electric vehicles has led the American Automotive Association to perform a comprehensive third-party study into the issue.

The new report released by the AAA analysed the performance of five battery electric vehicles in controlled conditions in temperatures of -6.6C, 23.9C, and 35C to represent driving in extreme cold weather, average weather, and extreme warm weather. All of the cars performed poorer in the cold and warm weather tests compared to the average case, resulting in lower overall range on a single charge.

Ambient temperatures of -6.6C resulted in around a 12% decrease in range and 9% drop in effective fuel economy, and temperatures of 35C resulted in a 4% reduction in range and 5% loss of fuel economy. These reductions came primarily from "the temperature dependency of both the recharge allocation factor (RAF) and battery discharge capacity" and happened independently of engaging heating or cooling systems for passengers.

When heating an cooling systems were used to adjust the vehicles' internal temperatures to comfortable levels, the additional drain on the battery exacerbated the range drop markedly. Heating the car from -6.6C reduced the car's range by 41% and cooling it from 35C reduced range by 17%, making this a significantly larger factor than the direct effect of ambient temperature on the lithium ion battery.

Source: AAA Report