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Why Do Electric Cars Only Have 1 Gear?

Why Do Electric Cars Only Have 1 Gear?


Hello everyone, and welcome. In this video we will be answering the question why do electric cars only have one gear. This will be the first of a five-part series brought to you 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 ePrix and was able to chat with team principals, hang out in engineering rooms during qualifying, and even learn from this Year’s champion Lucas De Grassi. Now the topic at hand is why electric cars use just a single gear and don’t have traditional transmissions like you’d find paired with internal combustion engines. While it might be more appropriate to ask why do gasoline engines need gears, electric motors can get away without numerous gears because they are high reving, remain fairly efficient across a very broad rev range, and produce a great amount of torque at low RPM while a gasoline engine will need to have multiple gears to reach a top speed an electric motor can easily be geared specifically for that top speed, and still be useful at lower RPM. For example, in Formula E, the cars typically won’t go any faster than 225 Km/h or about 62.5 m/s. The electric motors are capable of spinning at about 20,000 RPM, so we can do some quick math based on the tire data to see what our gear ratio might be. The rear tires have a diameter of 0.68 meters, multiplied by Pi gives our circumference. We’ll divide 20,000 RPM by 60 to turn revolutions per minute into revolutions per second and now we can solve for the gear ratio, which turns out to be 11.4. This means that if we have an electric motor that revs to 20k RPM with a gear reduction of 11.4:1 we could drive this electric car from zero Km/h at zero RPM to 225 Km/h at 20,000 RPM. And since many electric road cars have top speeds limited to less than 160 Km/h You can see how one gear would easily be enough even if the motor was lower revving or if the gearing was more aggressive. Well what happens if we were to take this same gear ratio of 11.4:1, and match it with an internal combustion engine with a redline of 6,000 RPM. Now yes, in racing you’ll find gasoline engines with much higher red lines but for road cars 6,000 RPM is a perfectly normal red line, while road cars with electric motors are still high revving. At 6000 RPM with a gear ratio of 11.4:1 the gasoline engine would only be able to drive the car up to a top speed of 67.5 km/h It would need much taller gearing in order to reach the top speed of 225 km/h In order to reach that top speed, it would need a gear ratio of 3.4 But what if we then wanted to drive at 20 Km/h? At 20 Km/h, with a gear ratio of three point four between the engine and the wheels the engine would only be spinning at 530 RPM. Far too low for the engine to operate and even if it could it would have very little torque. Hence, internal combustion engines use gears to keep the engine within the appropriate power band, and still allow for the car to travel at any of the desired speeds. Since electric motors are so high revving, and efficient across a much wider rev range, a transmission simply adds complexity, cost, weight, and efficiency losses, with little added benefit. Now does this mean that there’s never a need for electric cars that have multiple gears? Actually no, and in Formula E there are a wide range of strategies used. While this season’s team champion was Renault, who used a single speed, the drivers Champion was Lucas De Grassi, who was driving a three-speed Audi. So what are the advantages of adding a few gears? To better understand this we need to look at an electric motors power curve. In Formula E, during the race power is limited to 170 kW. At 0 RPM, because horsepower is a function of torque multiplied by RPM, power is 0. Power gradually increases until flatlining at the limit allowed by the series. Now for super low speeds, you can see that you’re not able to put down the full amount of power that the series allows which means there’s some opportunity here to gain an edge. As long as traction allows for it, more aggressive gearing means you can spin the motor up faster. You’ll have more wheel torque, can accelerate faster, and will be able to get into peak power faster than if the gearing were taller, meaning you’re accomplishing more work. In scenarios such as the start of the race, or during very low speed corners, this can play to your advantage. Gearing can also be dependent on the motors used. Smaller motors tend to have less torque, so multiple gears can be used to compensate. Larger motors, or pairs of two motors, will have more torque and can easily get away with just a single speed. With relatively low top speeds needed, high rev limits, and a wide efficient rev range, all of these features make it possible and beneficial for electric cars to use just a single gear ratio. A big thanks to formula E, and thank you all for watching. If you have any questions or comments, feel free to leave them below.

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100 thoughts on “Why Do Electric Cars Only Have 1 Gear?

  1. Perhaps your channel should be renamed “vehicles explained” since the majority of your content is the engineering behind vehicles?

  2. for motorcycles
    tire circumference of rear is needed or front
    do tell why u multiplied gear ratio by sixty
    also tell units to be used because formula provided by u are giving me some crazy nos.

    plz reply

  3. why are there electric Cars, that only use a single motor?
    is there any benefit in not dividing the power, that I don't see?

  4. If a car manufacturer make a fun and driver focused EV which drives perfectly on mountain roads and on track with 5 gear manual gearbox will you guys buy it?

  5. The author contradicts himself near the end. Up until then it was only one gear needed. Then states when the motor isn't that strong multiple gears are needed.

  6. I'm not entirely sure why they still use transmissions at all. Direct drive is perfectly fine in that envelope…

  7. I stil do not get why road electric cars do not have a cruise gear or 2. During cruising, you tend to not acellerate, but with only 1 gear, you just waste tons of electricity at higher speeds, even while not changing the throttle. So, why not having a cruise gear that allows the electric car to cruise at high speed and not consume u reasonable amount of electricity?

  8. I think as the technology progresses engines will get much smaller to compensate for the great demand of consumable copper. Surely there is some math to ascertain the smallest engine possible with the greatest power output possible. If you can do that equation, i think you'll need gears to keep the engines efficient as they become smaller.

  9. I have more question about formula-e now that i didnt know it existed. how did they recharge the car ? did they install new batterys ? how many times do they do that? make a video about that pls

  10. You can find something like this on the Avasva page. Full step-by-step instructions right on your desk.

  11. can a transmission be used to improve range for electric cars? so the motor can use less power for highways speeds and long driving. or couldn't electric cars just use a tall gear to increase distance? We don't need break neck acceleration for daily driving anyway. I'd prefer range over acceleration since it's not a race car anyway.

  12. Are you going to update this video to show that Electric cars DO have multiple gears? Rimac uses two speed, there are many enthusiast racers that use 3-speed manual shift automatic (planetary gearboxes) and Formula E ranges from 1 to 6 speed, settling on 3 avg. Even the Lightning LS-218 electric bike, while having a single stock speed, allows you to manual swap gears. This is an implicit admission of the need for gears.

    The problem is that torque drops as RPM increases so when you actually look at the dyno graph about midway through for DC, it drops right away, for AC it drops half way through. That's why power remains flat and doesn't increase. The drop in torque shows all the current being consumed turned into heat. It makes no sense to spend your time in this rpm range and is more efficient to shift to a taller gear to get back into its efficiency range.

  13. Because electric engines don’t have rpm limit. The max rpm is set by the max power the circuit will allow to get to the engine

  14. Aside from weight, why not use a specifically tuned CVT or IVT? I'M,? Looking into doing an electric sleeper with a potential for custom gearing if one gear ratio is more optimal than a standard mass produced tranny? Aside from engineering complexity, what would be the ideal transmission system be for an electric vehicle with regards to good launch speeds and high efficiency? If I dropped in a modified CVT to account for the different torque vs rpm curve, could I get reasonably comparable effencies? What would be theoretically ideal for an electric motor?

  15. Even better and even bigger even faster even efficient question is why don't we use CVT with electric motor….?? It's efficiency may take us more than just 500km in a single charge.. My toyota premio with cvt takes me more than toyota spec says it can take me.. it's so efficient..

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  17. 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 😉

  18. Wouldn't gears improve mileage though? Having gears would mean the motor could maintain a higher speed with less RPM, which would reduce power draw, no? Not a concern in races but for road travel the amount of miles you get from a charge can be very important.

  19. Ok wait… u just said at the end that multiple gears allow smaller motors to be as powerful as bigger motors… so why exactly don’t electric cars use smaller motors with for example 4 gears to produce the same amount of power as a motor that’s bigger but only has 1 gear? Wouldn’t that save energy? And for the save of energy wouldn’t you save weight because the battery don’t have to be as big (and heavy)? Or you could just leave the batteries alone and increase range?

  20. So why dont you tell anything about field weakening in that context? the only reason for mechanic gears in an electric racecar that comes to my mind, really is when you dont need the rpm. And maybe reving up the engine. I dont think that this would help much except for the start. And even during start I would expect you to get traction problems if you gear the motor down.

    Your video kinda upsets me. You have this bunch of examples where you could talk about field weakening. You are really motivating towards this topic and all you do is putting in some examples when mechanical gears can make sense…. Just not the whole picture

  21. i think with 20.000 rpm 1 gear can reach top speed at 225 kmh, so can we add more top speed with 2nd gear with that 20.000 rpm motor?

  22. Why dont electric motor have a overdrive gear like for more efficiency where the motor can spin slower at higher speeds for less energy consumption as the current electric cars consume a lot of energy at highway speeds.

  23. A machine isn't a machine without gears Gears are a sophisticated engineering symbol of progress Electric car with no gears pisses me off Electric cars work fine with gears gears live matters Geared machines forever!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  24. Using a smaller motor less powerful motor also means you reduce your power consumption and thus you can either reduce the size (weight) of your battery and have a lighter car which in turn needs a smaller motor to have the same performance.

  25. Electric motors with gear box is more economical for battery range. Because electric motors use high amps at low rpm

  26. 20000 RPM need very high quality of bearings ,lubricant and good motor cooling system. Need information including bearing life. Thanks

  27. I wonder what strategy the 2020 Tesla Roadster is using to achieve a top speed of "over 250 miles per hour"? Higher revving motors, a transmission, or a combination of the two? My guess is that it will be a single gear, but the gear ratio will be such that it will allow for a very high top speed. And they can afford to do this because the claimed torque on this setup is "around 10,000 newton-meters". Can't wait until the juicy details start coming out for this car!

  28. 0:39 “Now it might be more appropriate to ask why do combustion engines need gears”… Yes, it would be. Gears are the solution to a problem which apparently doesn’t exist for electric motors. The end.

  29. at high rpm, motor's torque is down quickly and energy consumption is very poor level.
    Fomula E has 3 speed gear.
    Why don't you explain that have more effect on high speed energy consumption.

    In the future. Electric Cars have gear system minimum 2 speed. I think.

    welcome anyones feedback.

  30. some main issues for road EVs with single gear:
    1. relatively low top speed (most EVs have top speed of less than 100mph)
    2. much slower acceleration from medium to high speed (50mph to 80mph)
    2. significantly more energy consumption at motorway speed (a Tesla at 80mph uses significantly more battery than at 70mph)
    these are putting me off EVs (assuming charging won't be much of a problem in 2-3 years' time with 300kw DC fast charge and 100kwh+ batteries on most affordable EVs)

  31. An electric motor can supply torque at zero rpm, which is why a clutch or torque converter is not needed to get the car rolling.

  32. But what is the difference in watts used between full and half RPM?
    I still think that electric cars should have 2 gears. 1 for normal road driving and 1 for motorway driving.
    With the 2nd gear you have the car speed at a lower RPM which would use less battery power but you'd have less torque which isn't really needed at that higher speed.

    Failing that, throw a CVT in there.

  33. Thank you for that explanation. Now , my question is: where can I watch the formula e races? It's not on ESPN channel, here in Texas.

  34. Anybody ever hear of the Daf 33, 44, 55 and 66?
    Daf cars had a Variomatic transmission… only 1 gear so to speak and a reverse.
    It was very clever, but did come with an annoyingly loud whine the faster the car went.
    The final drive was cone shaped and a belt would slip down the gradient effectively accelerating the car.
    One odmf the quirks was that the car could travel accelerating in Reverse with the same final drive.
    The problem was that these belts would wear out fast.

    This is just a simple example, but EV do not make enough torgue as they only have the Final Drive.
    I m still trying to figure out the conflicting hybrids if Toyota and Mitsubishi

  35. Cuz one gear is all a man needs, ow yea, chicka chicika, 🎶oooo bowmp bowmp buh dumpa dumpa bowmp bowmp.🎸🤘chick chicka!

  36. Beause a gearbox is designed to get the most torque out of a combustion engine. The power of a combustion engine is dependent on the number of revolutions where as an electrical motor doesn't have a dependency on the number of revolutions

  37. 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?

  38. what about "electric power" economy? Changing the gear ratio would help an electric motor to consume less energy, thus extends the range for a vehicle. But the cons of adding a gearbox to a vehicle is an extra weight.

  39. How would I go about calculating the type of e-motor I need to propel (x) amount of weight? ex. total weight of 150-200 lbs.

  40. aelectric motors have a wide range of RPM but it does not mean that you can drive an electric motor under load al low RPM, In that scenario, it produces heat, a lot of it. yo, with 2 gears will be enough. Direct drive tends to be a problem when it comes to deal with a little of weight.

  41. I don't think petrol powered cars will vanish anytime soon, they'll simply co-exist with Electric. Who knows, a clean renewable fuel that they can run on might be developed in the near future, meaning they can go on forever.

  42. Why dont they put gears on EVs to help improve efficiency when motorway driving. Reducing rpm. I can understand a single gear in performance, but surely for economy which evs are essentially aimed at in the consumer market, gearing would be a good idea?

  43. I think with a gearbox an electric car could use much less power to keep the car in speed at for example 120km/h, thus the range of the car would multiply.

  44. In a road car, an electric motor could greatly benefit from an overdrive gear for use at highway speed, right? Something to drop the revs down to something like 1500 or 1000 rpm at 70 mph. This would greatly improve mileage on long road trips.

  45. Actually, formula e cars have a gearbox with 5 gears… don't know how it works but i watched an official video mentioning it multiple times 🤔

  46. Close to a decade ago now Charlie Sheen said he only has one gear go…. Elon Musk said brilliant!

  47. Ooh, Formula E! I've recently become a big fan of them.
    I like that they post all of their races here on YouTube.

  48. Sure, you can tune a motor to have enough torque and power to go 200mph but why not use an incredibly efficient motor paired with a CVT for longer range/power life?

  49. Not to bash your very informative video but a 6000 rpm is normal red line for general car but which car/country that normally have max speed of 225 km/h?

  50. What!!! Even my old Toyota pickup 4wd electric RADIO CONTROL . ( Stress relieving tool) had two gears! . This is just miserable scrimping

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