Of all phases of flight, vertical manoeuvres demand the most energy from an eVTOL’s battery system and produce significant heat. Takeoff and landing are particularly power-hungry because the motors handle the full load, while in cruise the wings share the burden by generating lift. After landing, battery temperatures can easily exceed 60°C, immediately facing another thermal challenge as they need to be fast-charged to maintain optimal turnaround times1.

Lithium batteries perform best within a 10-45°C range. At high temperatures, there’s a risk of fire, and at low temperatures, lithium plating can occur—where a layer of metallic lithium coats the anode, reducing performance.

Electric aircraft companies like Joby Aviation and BETA Technologies are developing ground-up cooling methods specifically for aircraft. Unlike the automotive industry, aircraft chargers themselves can be integral to the cooling system.

Joby Aviation’s S4 eVTOL (Credit: Joby Aviation)

While eVTOLs may carry liquid coolant in flight, ground-based chargers can also circulate coolant through the aircraft to remove excess heat from the batteries.

For aviation insurers, battery safety is a key concern when underwriting Advanced Air Mobility (AAM) risks. Thermal runaway events could result in hull losses and costly liabilities—even if aircraft are unoccupied, such as when parked in a shared hangar or near other aircraft. Insurers will therefore assess both the manufacturers’ infrastructure and the operators’ charging protocols as eVTOLs enter passenger operations, facing the commercial pressures of civil aviation.

1 Yashraj Tripathy from About:Energy in Aerospace America

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