Briefly stated, technologies are generally described for harvesting energy for a vehicle having an engine and a torque converter. In various examples, an energy harvesting system is described, where the torque converter may be configured to have an input shaft driven by the engine, and an output shaft. Each of the input shaft and output shaft of the torque converter may be mechanically coupled to one of a first portion and a second portion of an electric generator. The electric generator may generate electrical energy using a rotational speed difference between the input shaft and the output shaft of the torque converter. As a result, the electric generator may store at least a portion of the electrical energy, which otherwise would be lost at the torque converter, in a charge storage device. The stored electrical energy may be transmitted to an assist motor configured to drive a rotation of wheels.