During the colder months of the year, public transport operators must adapt to conditions that directly affect the range of their electric buses.
In extreme sub-zero temperatures, the range of these eVehicles can be reduced by between 20% and 30%, according to a report published by Yutong.
As Michael de Ruiter, Chief Performance Officer at Transdev Nederland, mentions to Mobility Portal Europe: “During the winter, the range is lower. The important thing is to adjust schedules and operations considering this factor.”
He explains: “Thus, every year, it is essential to update the planning with the anticipated range of the vehicle.”
What challenges do eBuses face during the sub-zero season?
Bruno Lapeyrie, Director of the Energy Transition Excellence Centre at Keolis Group, tells Mobility Portal Europe: “We have a great deal of experience with cold climates, and we understand that there are three effects.”
The first is the additional energy consumption required to maintain the internal temperature of the eBus, especially on routes where doors are constantly opening and closing.
This factor can account for between 15% and 20% of total energy consumption, according to the report published by Yutong.
Secondly, there is the inability of the cells to regenerate energy during braking.
“No one had anticipated this,” says Lapeyrie.
He adds: “When the battery, located on the roof of the eBus, is too cold, the system cannot regenerate energy during braking, which leads to an estimated loss of at least 15% of energy capacity.”
The third challenge is the additional time required to reheat the batteries before charging them.
In this regard, he explains: “If the cell is too cold, you cannot charge it, so you have to heat it up. You lose an initial hour of charging just to reheat the battery.”
According to the Keolis representative, this delay can compromise the availability of vehicles for the next day, especially in systems with tight schedules.
What is its experience?
In countries such as Sweden, Norway, and Canada, where winter temperatures regularly fall below -15 degrees, these challenges become more acute.
“The age of the battery decreases by approximately 2% per year, and most of the time, we plan to replace it after eight to ten years of operation,” he details.
This wear and tear, combined with the additional losses caused by the cold, can reduce the battery’s lifespan.
“In the last year, we would have lost 25% of the range,” confirms Lapeyrie.
It should be noted that each season has its own challenges.
For example, in summer, chargers, when exposed to the sun, tend to overheat, reducing their power output.
What solutions are eBus manufacturers implementing?
According to the report from Yutong, innovations include battery heating systems and intelligent energy management to balance range with heating needs.
These technologies enable operators to maintain operational efficiency even in extreme climates, although they represent an additional cost.
On the operational front, companies like Alsa are adopting specific strategies to deal with winter.
“Charging is done in the garage overnight, as the eBuses need several hours to properly ‘refuel’,” the company explains.
This approach not only ensures a full charge but also minimises downtime during operating hours.
This demonstrates that the experience of operators plays a central role.
Sveinung Kvalø, Senior Advisor at the Norwegian Association of Electric Vehicle Drivers, points out that “many drivers need a few winters to gain experience and learn how to handle these units in cold climates.”
The experience of Oslo
At the end of 2023, during the winter, a series of eBuses experienced complications and failures that slowed down the public transport system in Oslo, a city where most of these vehicles are electric.
Historically low temperatures recorded in the country’s capital allegedly paralysed the operation of 90 units.
In this context, industry specialists affirm that these challenges are not exclusive to electric vehicles.
According to Arild Hermstad, leader of the Green Party, “extreme weather and snow also caused problems with diesel buses in 2015.”
This puts into perspective that technological limitations are not exclusive to electric mobility but are inherent in any transport system operating under extreme weather conditions.
