Vehicle operation mode systems and methods

A system for controlling a mode of operation of a driver operated vehicle having a rechargeable energy storage system (RESS), an engine configured to drive an electrical generator, and a drive motor coupled to the RESS and the engine, the drive motor selectively powered by at least one of the RESS and the engine, the system comprising:

• a controller operable to adjust the vehicle to operate in at least two operating modes including a first mode of operation in which the drive motor is powered only by the RESS and a second mode of operation in which the drive motor is powered by electrical power provided by the engine driven generator;
• a switch for the driver to select either the first mode of operation or the second mode of operation;
• a second switch for the driver to select either a first mode of braking operation or a second mode of braking operation;
• wherein when the driver operates the switch to select the first mode of operation the controller is configured to maintain the system in the first mode of operation and ensure that the only power source for the drive motor is the RESS regardless of the power demanded by the driver;
• wherein when the driver operates the switch to select the second mode of operation the controller is configured to operate the engine to generate electric power for the drive motor;
• wherein, when the second mode of operation is selected, the controller is configured to operate the engine as necessary to maintain the RESS at or above a predetermined state of charge;
• wherein, the controller is configured to automatically switch the mode of braking operation when the vehicle detects a grade change in a road.