this post was submitted on 03 Feb 2024
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Quickly becoming a moot point. EVs don’t even have gears to shift. Single speed forward or reverse. Shifting gears will eventually be like dialing a rotary phone.
I'm not sure if that's the most efficient use of resources. EVs can only be gearless if they have over a half-ton of batteries providing huge amounts of power to their electric motors.
PHEVs, such as Prius Prime, Volvo or other cars (US Market, sorry I don't know UK market too well), do have an EV-only mode. But the smaller batteries force them to use CVT or other automatic transmissions so that their torque/horsepower bands can be better matched.
I'm not convinced that having all of our cars filled with half-ton to 1-ton batteries is the best design.
I’m going to knock your socks off… The vast majority of “normal” EVs don’t have gears as such. There are one or two supercar EVs that have a high and low gear but that’s it. Many hybrids don’t have gears either. My Accord Hybrid has an “eCVT” which is just marketing bullshit for covering up the fact that it’s functionally an EV with a gasoline powered generator. Honda has programmed the ECU to do fake shifts to make boomers feel more comfortable with the new technology. It’s only imitating an automatic transmission with software trickery. The gas engine isn’t even mechanically connected to the wheels for like 95% of the driving I do. IIRC that tech was borrowed or heavily influenced by the Prius.
https://www.youtube.com/watch?v=jofycaXByTc
I've decided to do some research on eCVT. I was surprised at its actual implementation. Toyota Prius, Ford Escape, and probably Honda Accord does this.
Its basically planetary gear magic. A computer can control two or three inputs, while the outputs are hooked up to the wheels of the car. By changing the speed of the variable input (likely the electronic engine)... the effective gear ratio of the "constant" input (likely the ICE engine) is modified. In the most extreme case, the variable input runs backwards to have the "overdrive" gear ratio.
It seems like the Honda Accord is a planetary gear eCVT system. Planetary gears are always so cool, I didn't realize that a CVT could be implemented with one (albeit with a hybrid vehicle where you have 2 or more powered inputs).
EDIT: it appears that you are correct. Honda's Hybrid system is different than what I'm familiar with (which is what the above video demonstrated).
https://youtu.be/QLUIExAnNcE?si=7JzkfL8GfUUoFnbK
So you're right with regards to Honda Accord Hybrid. Very interesting. Its always surprising to me how different car companies are with their implementations.
I'm well aware of the larger torquebands across wider RPMs of electric motors vs ICE motors, especially the high torque available at 0 RPM. But that doesn't change physics or chemistry.
Porsche Taycan isn't a supercar, and it has this high/low gear / Two-speed transmission for its EV, because at higher RPMs even an EV will run out of torque, and it becomes a good idea to convert RPM vs Torque through the use of a gearbox. Gearboxes / Transmissions have been used for a hundred years. They are among the most sophisticated parts of a modern car, and are made with cheap steel and highly automated manufacturing today.
Every motor will have a limit to their useful torquebands. EVs have the widest torque vs RPM in existence ever, but even the biggest motors and biggest EVs have problems.
This is complicated by the fact that Hybrids are far smaller electric-motors with far less battery power than the pure EVs like a Porsche Tycan. As such, the incredibly popular Toyota Prius Prime opts instead for a proper CVT transmission. And I'm willing to bet that Prius Prime 2024 is getting a better driving experience in practice.
Furthemore: there's something to be said about sophistication of dumber / simpler metals. Steel is found everywhere. Trading cheap steel for Lithium, Copper, and Cobalt sounds like a bad idea to me in general. I guess that copper/lithium is lighter than Steel so saving on weight is helpful, but there's some crazy bad environmental problems associated with these rarer and more complex metals.