Designs for a battery-powered, all-electric locomotive and related locomotive and train configurations are provided. In one particular exemplary embodiment, a locomotive may be driven by a plurality of traction motors powered exclusively by a battery assembly which preferably comprises rechargeable batteries or other energy storage means. The locomotive carries no internal combustion engine on board and receives no power during operation from any power source external to the locomotive. A battery management system monitors and equalizes the batteries to maintain a desired state of charge (SOC) and depth of discharge (DOD) for each battery. A brake system may be configured to prioritize a regenerative braking mechanism over an air braking mechanism so that substantial brake energy can be recovered to recharge the battery assembly. Many locomotive or train configurations involving battery-powered or battery-toting locomotive(s) may be implemented. In one embodiment, a battery-toting locomotive is directly coupled with and positioned between two diesel-electric locomotives, wherein the batteries recover energy from regenerative braking and/or supply power to drive traction motors.