Patent ID: 7073615

Claim:
A method for use in an electrically driven vehicle having a primary drivetrain and an auxiliary drivetrain, the method comprising: controlling a driving characteristic of the auxiliary drive train based on a first performance limiting strategy, the first performance limiting strategy based in part on future availability of the primary drivetrain; and switching control of the driving characteristic to a second performance limiting strategy, the second performance limiting strategy based in part an future unavailability of the primary drivetrain; wherein the second performance limiting strategy comprises setting a plurality of maximum vehicle speed ranges based on battery state of charge for a battery used to power an electric motor of the auxiliary drivetrain; and wherein setting the maximum vehicle speed ranges comprises setting the maximum vehicle speed to one of 45 mph if the battery state of charge is above 50%, 35 mph if the battery state of charge is between 50% and 45%, 25 mph if the battery state of charge is between 45% and 35%, and 15 mph if the battery state of charge is between 35% and 20%.