Why Do Electric Cars Only Have 1 Gear?

Why don't electric cars have multiple-gear transmissions?

Big Thanks To Formula E For Sponsoring This Video! Channel Link:

Why do electric cars only have 1 gear? This is the first of a five part series sponsored by Formula E, who I’ve partnered with to talk about the engineering behind electric cars. I had the opportunity to get behind the scenes at the New York City E-Prix, and was able to chat with team principals, hang out in the engineering rooms during qualifying, and even learn from this year’s champion, Lucas di Grassi.

So why do electric cars use just a single gear, rather than using traditional transmissions like you’d find paired with internal combustion engines? Electric motors can get away without numerous gears because they are high revving, remain fairly efficient across a very broad rev range, and produce a great amount of torque at low RPM.

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[adam]

Now imagine Fast and Furious movies with only one gear. What will they do without dramatic gear changes every 10 seconds?

[wardencobb]

If they really wanted the sport to succeed in overtaking F1 as the premiere racing championship, FE needs to massively raise the power ratings to encourage what in F1 is often known as "cheating". I'm dead serious. They need to cheat. Cheating means innovation, invention, intelligent designs, creativity... The teams need to become manufacturers of their own batteries, motors and everything else like in F1 so they can start cheating like crazy... And then the general public gains from this and road cars get better.

[PatrickGSR]

After riding my e-bike over 1, 500 miles in the last 5 months, I'm thankful to have retained the 8 gears on the rear wheel. One thing I've learned is that low speed with a high-powered electric motor = HEAT! And also big power drains from the battery. By starting in a lower gear on my e-bike, I can keep the motor turning at a relatively higher RPM, which is better for both the motor and battery. Then as I increase speed I gradually shift through the gears. Works awesome.

[FIAFormulaE]

Great video; thanks for dropping by. See you next season!

[caverntaylor]

How exactly do electric motors deliver full power instantly and stays constant over the rev range, whereas combustion engines gain/lose power/torque as rpms increase?

[Sayua-chan]

That must be the most quiet car race on earth

[toofastnobrakes]

What if it was applied in a heavy duty towing application? Wouldn’t multiple gears be feasible for torque multiplication at lowers speeds, also would a higher gearing yield more range out of the battery? Stressing it less at higher speeds should lower power consumption right?

[amadodiego]

finally someone civilized who uses km/h

[uNails]

Feels like I just watched a Discovery Channel show! Awesome editing and voice over. This is a must see video.

[obananamano]

no gearbox AND clutch. I reckon anyone who works on their own cars would love the simplicity of electric drivetrains

[latinokooll]

Good video, one suggestion for you is to explore how could more gears coupled with smaller electric motor could help to mitigate the range issue on electric cars.

[FunnyHacks]

Thank you, thank you, thank you for explaining this so well. For years I've been sick of people saying that electric motors produce full power and efficiency across the entire RPM band.

[walkerscranger]

Someone had asked me about this and as I started my research your notification popped up. Interesting... I just simply forwarded your video. As usual... awesome job!

[maxtorque]

It's also worth noting that the effective "gears" are created by changing the winding geometry of the eMachine, where you trade off maximum torque vs rotational speed for any given power value. A higher number of turns means more torque (more ampturns) but also means lower maximum speed because the KE of the motor is similarly increased. However, as it's the inductance of an eMachine that fundamentally limits it's ultimate power capability (for any given supply voltage), and inductance increases as the square of the turn counts, you'll find the trend for maximum power eMachines to be towards, smaller, higher speed, lower torque architectures, and these could/will need gears in order to meet the low speed (and zero speed) tractive effort requirements

[Wojciech]

I am a car guy and love traditional combustion engines, but electric-powered cars are outperforming them- just as cars were outperforming horse-powered transportation at a distant place in time.
The future is efficient and torque'y, but completely mute.

[eDriver]

good explanation, how this works with electric cars.
Most people think that electric cars have gears. People calling the drive mode switcher a gear shifter, but it's not, because there are no gears.
Also somebody told me already, that she don't like that low noise electric car, because she will not know, when to change the gear ;-)

[jamos]

I'm very curious on the use of gears for efficiency, can you get more range from a lower revving motor? Or is power usage not proportional to the rpm?

[domingos]

That was great. Another great way to show this is: drawing a graph that show on a combustion engine at what speed is the car going at each gear on top efficiency and another on the electric motor

[ConnorwithanO]

You could also think of the electric motor itself as the transmission, as is the case on many locomotives. On diesel locomotives, for instance, the traction motors generate very high torque when accelerating from a low RPM, and generate proportionally less torque at higher RPMs, thus outputting the same power at a wide range of RPMs. This effect is called motor stalling, and it essentially causes the motor itself to act like a continuously variable transmission. Hence the motor acts like a low gear when accelerating from low speed, and acts like a high gear as it reaches the desired speed. The reverse of this effect allows the motor to act as it's own brake, which is called dynamic braking, or regenerative braking when it's used to recharge the battery during deceleration. This is why diesel and electric locomotives are able to generate the huge amounts of torque required to start massive freight trains, whereas steam engines have difficulty pulling large trains at low speed.

[inkro]

Does electric motors electric efficiency decline with speed? I mean, does it consume more electricity to drive the same electric motor at 20k and at 10k RPM if both are are the same RPM (like 170 kW in Formula E)?


I had the opportunity to work with a 11 kW motor (says the manufacturer) and I had it working at up to 48 kW but just after the peak power it just started dropping (a lot) but I still had the engine sucking up 48 kW electrical energy.


I'm just wondering if that was just the controller that wasn't properly set up, if there was too much friction losses or if the electric motor itself becomes less efficient.... Could that be a reason to have multiple gears so you avoid running in that high rpm low efficiency state?