New, immature technology has new (and interesting
) failure modes. Batteries were a big concern - hence the 8 year warranty on the battery -- but the battery warranty is not much use if the motor/gearbox/EME fails after five years and 90K miles.
Quite a bit of EV related electric motor bearing wear research out there :
Paper: Electrical bearing failures in electric vehicles Feng HE, Guoxin XIE*, Jianbin LUO* State Key Laboratory of Tribology,
Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China Received: 08 September 2019 / Revised: 26 November 2019 / Accepted: 17 December 2019 © The author(s) 2019.
Abstract: In modern electric equipment, especially electric vehicles, inverter control systems can lead to complex shaft voltages and bearing currents. Within an electric motor, many parts have electrical failure problems, and among which bearings are the most sensitive and vulnerable components. In recent years, electrical failures in bearing have been frequently reported in electric vehicle
s, and the electrical failure of bearings has become a key issue that restricts the lifetime of all-electric motor-based power systems in a broader sense
. The purpose of this review is to provide a comprehensive overview of the bearing premature failure in the mechanical systems exposed in an electrical environment represented by electric vehicles. The electrical environments in which bearing works including the different components and the origins of the shaft voltages and bearing currents, as well as the typical modes of electrical bearing failure including various topographical damages and lubrication failures, have been discussed. The fundamental influence mechanisms of voltage/current on the friction/ lubrication properties have been summarized and analyzed, and corresponding countermeasures have been proposed. Finally, a brief introduction to the key technical flaws in the current researches will be made and the future outlook of frontier directions will be discussed.
All that current flowing around when you max the throttle could
take out the motor bearings. This failure mode doesn't exit in ICEs.
If you go into your dealership with bearing noise from the back end, the first thing they will tell you is .... Sorry to say motor/gearbox failure does happen and if not covered by the warranty that'll be 9k ... thank you.