Understanding vibration frequencies experienced by electric vehicle batteries

There has been comparably little research published critically examining the mechanical integration of the high voltage (HV) battery within either a battery electric vehicle (BEV) or a hybrid electric vehicle (HEV). The effects of vibration on electrical and electronic components and subsystems are potentially a major cause of in market durability failures. If excessive warranty claims are to be avoided, it is important that engineers tasked with the design of the HV battery system properly understand the magnitude and frequency of the vibration inputs that the system will be exposed to during the vehicle's predicted life. This paper outlines a study into the typical vibration input levels experienced by a range of BEV's and their battery packs when subjected to customer representative road surfaces. This research was conducted through the instrumentation and measurement of the vibration behaviour of the HV battery packs installed within a selection of commercially available BEVs and HEVs when driven over the repeatable surfaces at Millbrook Proving Ground. The primary conclusions are that there is evidence to suggest that the RESS construction, the associated cooling strategy and surfaces associated with a vehicles operational environment will impact the vibration behaviour observed by the energy storage device. There is also evidence to suggest that Engineers need to consider vibration frequencies above 300Hz when designing HV battery systems as it has been observed within this study that high frequency vibration from power electronics, electric drives and thermal management, can all be transmitted to the on-board energy storage device. Finally, results are presented within this document highlight the necessity for engineers to consider the battery vibration isolation strategy and the RESS to body integration as mod