Motors don't have infinite RPM range, at high RPMs back-EMF prevents you from spinning them faster.ericsf said:I don't think so. The electric motor can deliver max torque at zero speed and can spin way faster than needed (the LEAF's top speed is electronically limited). A fixed ratio gear transmission or no gears at all is all an EV needs. The weakest link is the inverter and the battery. What limits the performance and how much power you can draw through them.
At a possible cost in efficiency. It's amazing how inefficient even a simple fixed gear reduction can be.drees said:A transmission will definitely allow one to use a smaller motor for a given performance threshold.
Yes, but properly designed a transmission will improve overall efficiency.DeaneG said:At a possible cost in efficiency. It's amazing how inefficient even a simple fixed gear reduction can be.drees said:A transmission will definitely allow one to use a smaller motor for a given performance threshold.
While GM's secret sauce in the Spark EV lets it produce about twice as much torque, it runs out of steam at about half the speed. Net result - an improvement in efficiency thanks to having to spin the motor and input gear on the transmission half as fast, but it's no miracle.LTLFTcomposite said:With the secret sauce in the Spark's motor it seems this would be unneccessary long term. Assuming a manufacturer has enough patents to cross license with gm.
The motor draws the least amount of current when it's not moving anywhere. But the efficiency is also at it's lowest.fotajoye said:Without getting too deeply in the subject details, suffices to say there is a area of the torque/RPM curve that represents the most efficient rpm and load to run the motor; that area is usually where the motor draws the least amount of current while moving the car. to the best of my memory, I believe that point on the Leaf is about 30-40 mph on level ground with the present drive line.
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