Regen will usually only gain you 3-5% total range, most of the power from biking is dissipated as heat through aero drag, even if you're biking up and down hill

Regen will usually only gain you 3-5% total range, most of the power from biking is dissipated as heat through aero drag, even if you're biking up and down hills. Source – my company exclusively does ebike research and development.