We examine some basic physics surrounding regenerative braking and air drag. First, we analyze under what conditions it becomes energetically favorable to use aggressive regenerative braking to reach a lower speed over ``coasting'' where one relies solely on air drag to slow down. We then proceed to reformulate the question as an optimization problem to find the velocity-profile that maximizes battery charge. Making a simplifying assumption on battery-charging efficiency, we formulate the recovered energy as an integral quantity and solve the associated Euler-Lagrange equation to find the optimal braking curve. Using Lagrange-multipliers, we also explore the effect of adding a fixed-displacement constraint.
@article{arxiv.2106.14686,
title = {Optimizing regenerative braking -- a variational calculus approach},
author = {L. Q. English and A. Mareno and Xuan-Lin Chen},
journal= {arXiv preprint arXiv:2106.14686},
year = {2021}
}