For example, changing gears without a clutch relies on synchromesh within the transmission to match the motor speed with the transmission speed before a new gear can be engaged.
However, AC electric motors like the one in MR02EV are reversible - they can behave as a motor and a generator. When the motor is operating as a generator (in regen mode - when I take my foot off the accelerator) it dramatically slows the motor and transmission. This hinders the operation of the synchromesh and down shifts result in clashing and crunching of gears.
The way around this is to allow the motor to spin freely when attempting to change gears and allow the synchromesh to match motor and transmission speeds.
Regen is a great thing. It provides a kind of engine braking and transforms kinetic energy from slowing car into electrical energy which charges the batteries. So I didn’t want to permanently disable regen, but I needed to change gears.
I found a shifter knob with a button from B&M Transmissions (product code BM46112) which is used in 4x4 vehicles to engage differential lockers. In my case I use it to temporarily disable motor regen and change gears!
I have a Degree in Electrical Engineering from the University of Technology Sydney and am employed in Broadcast Television Industry. My hobby is the (continuing) modification of MR02EV. I am also the National Treasurer of the Australian Electric Vehicle Association.