Part 1: https://ssj3gohan.tweakblogs.net/blog/11470/why-fuel-cell-ca...
Part 2: https://ssj3gohan.tweakblogs.net/blog/11493/why-fuel-cell-ca...
Part 3: https://ssj3gohan.tweakblogs.net/blog/11556/why-fuel-cell-ca...
Part 4: https://ssj3gohan.tweakblogs.net/blog/11572/why-fuel-cell-ca...
> Besides the battery, the biggest component(s) by weight is/are the motor(s). Current generation electric cars use still fairly heavy central motors with an actual axle to the wheels. Upcoming generations will use in-wheel or near-wheel motors that have almost no drive train associated with them: no transmission, no gearing at all, no weight lost to things that aren't necessary. This is one of the reasons electric cars can actually become lighter than traditional gasoline-powered cars; the chassis can be reduced because there are almost no driving forces on it anymore. Note though: this is an advantage of both battery and fuel cell electric cars!
Motor on the wheel seems so obvious but still no one seems to build such a car. I’ve asked automotive engineers about this and the answer I get is often:
Wheel based motor would make the wheel heavier and thereby increase rotational inertia which decreases acceleration and increases the required (kinetic) energy for a given speed of the car. I also heard that the increased wheel weight reduces the performance of the suspension.
I suppose another problem is the need for two (4 for 4WD) gear boxes, since electric motors are low torque, high rpm. The author says „no gearing at all“ but how is this feasible with an electric motor?
Anyone in the knows can comment on this?
You can make lower RPM electric motors that can do direct drive but they will loose efficiency, power and speed. At some point gears became better to reduce the RPM, even after accounting for gear loses. Even current electric cars really need 2-3 gears for maximum performance and efficiency, but they can get away with fixed gears which greatly simplifies things. One of the interesting things about the 4 wheel drive Tesla’s is that the 2 motor/gear assemblies are optimized for different speed bands so they can have the benefit of both without needing to shift gears, they just shift power from one motor to the other.
In wheel motors generally will only be done for low speed applications where a suspension is optional, just like airless and omnidirectional tires.
> This is an extremely long, in-depth blog series, so I'll start by giving you a summary.