When commissioned by a Belgian client to develop an electric trike, Stuart Mills adopted a reverse trike layout i.e. two wheels at the front and one at the back. This was favoured due to improved stability under hard cornering and simplicity of a drive system to the rear wheel without the need for a differential which would have added to the weight. Two motors were experimented with during development. These included an AC brushless motor, but the more conventional DC brushed motor was the final choice due to the extra torque at lower rpm. The system runs at 72 volts and the 40 amp hour pack gives the trike a range of 35 miles. Acceleration is brisk, but the controller was developed to enable peak current and throttle ramp settings to be altered to extend the range and minimum voltage settings were introduced to protect the pack. The final drive gear ratios limited the top speed to 46 mph. The centre of gravity was kept extremely low with the batteries fitted slightly below the axle line, thus under hard cornering the trike tends to sideways drift rather than lift a wheel. Stuart drove it to victory in the UK’s 2008 electrathon. Like minded people considering alternative fuel transportation can buy build plans for £50 on the Mills Extreme Vehicles Ltd web site.
Design and Build a SPORTS CAR