First Student employee Yann Tschallener charges an electric school bus on a snowy day in Quebec.
A 2022 National Renewable Energy Laboratory study
showed electric transit bus range decreased by 33 percent when the air temperature was 25 degrees, as the battery’s chemical processes reduce available power and energy. Battery thermal management systems track energy
drawn from the electric bus batteries during idling or charging to warm up the battery, enabling it to optimally perform in all conditions. Alex Cook, First Student’s chief engineer, said the
required battery thermal management system tempera- ture varies by bus manufacturer. Battery chemistry with lithium-based chemistries have different thresholds. Insights from testing electric school buses in Quebec, Minnesota, and Rochester, New York, during winter reveal key considerations, Cook said. “For all-battery electric buses without auxiliary heat,
the recommended approach is to charge the bus over- night,” he shared. “Upon the driver’s arrival, starting the vehicle or activating internal heating will initiate the battery thermal management system, preventing range loss while warming the interior. The goal is to defrost
and warm the bus extensively before unplugging for the route, ensuring full battery storage.” Some districts opt for diesel fuel-fired auxiliary heaters
to preheat the cabin, seats and bus floor, raising the thermal mass to a temperature higher than ambient to enhance comfort and extend range, Cook added. A charger with sufficient capacity can handle cold
weather conditions, he commented, preventing range loss due to excessive energy consumption during preheating. As for range, internal combustion engines (ICE) beat
electric due to large fuel tanks, alleviating range anxiety, said Cook. He added that a 40-gallon diesel tank can provide more than 300 miles, while electric buses typi- cally achieve around 100 to 120 miles in ideal conditions. The Electric School Bus Initiative noted that Three
Rivers Community Schools outside of Kalamazoo, Mich- igan found its electric buses with a diesel heater have outperformed their internal combustion engine buses. Rick Lehnert, president, of HVAC manufacturer Transair,
said proven heating systems on conventional ICE school buses utilize wasted heat from the engine, which is trans-
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