US Patent 8700284 Charge while being flat towed feature for electric vehicles

A towed vehicle is towed by a towing vehicle. The towed vehicle includes a motor/generator for both regenerative braking and for powering wheels. A tow member connects the towed vehicle to the towed vehicle. A sensor measures or infers the tension and compression in the tow member. A computer communicates with the sensor and with the motor/generator. The computer commands the motor/generator to either utilize regenerative braking or provide assistance in propulsion of the towed vehicle based upon the tension and compression forces in the tow member.