Estimating Brake Pad Life in Regenerative Braking Intensive Vehicle Applications

Regenerative braking without question greatly impacts brake pad service life in the field, in most cases extending it significantly. Estimating its impact precisely has not been an overriding concern - yet - due in part to the extensive sharing of brake components between regen-intensive battery-electric and hybrid vehicles, and their more friction-brake intensive internal combustion engine powered sibling. However, a multitude of factors are elevating the need for a more accurate estimation, including the emerging of dedicated electric vehicle architectures with opportunities for optimizing the friction brake design, a sharp focus on brake particulate emissions and the role of regenerative braking, a need to make design decisions for features such as corrosion protection for brake pad and pad slide components, and the emergence of driver-facing features such as Brake Pad Life Monitoring. Tackling this question raises questions such as “is the proven braking energy and temperature based wear model still sufficiently predictive of wear or do other mechanisms become dominant?”, and “how does customer behavior for charging and discharging of the battery affect brake pad life?” In the present study, validated models for brake pad life in the field are adapted for regenerative braking equipped vehicles, including simple models for the battery charge acceptance power, battery state of charge, electric drive unit characteristics, and customer battery charging habits. After correlating with field data, the models are used in case studies to illustrate some of the important considerations for friction brake wear on regenerative brake equipped vehicles.