this post was submitted on 31 Oct 2023
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Overdrive puts the engine in a lower RPM band which would save the battery I feel like. Plus a few cars have em.
Electric motors don’t like low rpm’s. You’ll end up using more battery as the torque requirement to move the taller gear set is higher.
So a small high RPM motor that doesn't have a lot of torque and needs higher gear ratios to make up for it but uses less electricity in trade is out?
Seems silly to me.
So it’s just how electricity works. With an ICE engine you have a powerband, and the individual gears solve the issue of power and efficiency.
CVTs also solve this issue by putting the ICE motor at peak rpm efficiency for the task. Eventually with an ICE motor the rpm’s can only go so low or else you’ll lug the motor introducing extra heat and pressure that will blow it up.
Back to electric, what happens when you turn a switch on in a room to power a light or fan? Why are fan settings 0-3-2-1 and not 0-1-2-3?
It’s because motors are designed to come on at full power to overcome mass. If you were to introduce a taller gear set like an ICE motor, even at higher speed, you’re introducing the motor to higher resistance than the voltage can overcome so it puts extra stress on the electric motor which in turn increases the amperage.
This will consume more power, and create excess heat, thus lowering efficiency. Not to mention the vehicle has to overcome drag and air resistance and the extra weight of this new drivetrain on an already heavy vehicle.
Now, that’s not to say it isn’t impossible or impractical, but there’s no real efficiency to be gained since electric motors maintain same or similar efficiency across all ranges.
That all makes sense except why do some EVs have real gears? I feel like Porsche probably knows what they're doing when they put one in theirs.
Theirs unfortunately has no efficiency benefit. There’s two motors in the taycan, front and back.
Front motor is single speed, and once the car hits 62mph it shifts to second in the rear motor only.
The taycan is all about being fast, not efficient.
Maybe that's the use for a transmission then? Like CPU cores, efficiency cores and performance cores? Dunno, not an expert here. I do think what we think now is unlikely to be what we think as the technology matures and gets reinvented.
Yes, in reviews and media documents it is mentioned the Taycan has the second gear to be able to maintain Autobahn level speeds. It’s not explicitly mentioned, but Porsche won’t outright confirm efficiency last I looked, so even they don’t think it helps range. Just speed.
But it’s not that there isn’t efficiency to be gained, it’s just so small it’s not worth it. In order for even a 2 speed ev, the shift point would need to be approximately 70-80mph to realize efficiency gains.
That’s just not something that’s done with EV’s. Most are city centric, and even if you are driving 70-80mph in an EV, you’re hitting peak efficiency of the motor anyways. It’s a bell curve, so it’ll only start to taper off not drop like a cliff. Although, the one side might drop faster due to how resistance works.
My wife's EV peak efficiency seems to be 45mph give or take. That's where we get the most range. If we do a lot of local driving or a lot of interstate driving we get less range it seems.
I don't know nearly enough about this subject and appreciate the back and forth, I just feel like that problem can be solved better than it is today and feel like there might be a place for a transmission.
Though in the end this whole thing started by hating "fake" transmissions as much as fake vents on cars. My taste isn't global and I don't think everyone should think like I do. Though I do love manuals and would love a real reason for a manual on an EV. My car is amazing but as a gas car I know an EV version (once they get better batteries for lower weight) is solved would be really compelling but I don't want to lose the manual.
I get that it might not be realistic but it's part of my view on why I lean the way I do. Just trying to paint a picture of my mindset.
Right on. I apologize if I came off a little gruff, there’s a lot of stuff to try and say on this subject haha. Trying not to get too wordy.
But the manual EV can be done. Ford released the “Lithium” concept in 2019, and if you take a look at Autoblog website, Toyota just unveiled their “manual EV” prototype. It even simulates stalling!
I’m sure we’ll get there! But the demand just has to be high enough which makes it difficult. Manual take rate over the last few years has bounced around 3-5% in the US.
It doesn’t help that there are fewer to choose from every year. Even the base mustang doesn’t have a manual anymore.
Same with the C8 Vette which is why I went with the C7. With modern dual clutches and EVs the need from a performance standing isn't there anymore and with volume so low it often costs more for the manual even though it's a simpler component. Now it's just an enthusiast option and I'm an enthusiast seeing a device I love slowly fade away.