Why don't EV's have transmissions?

[Jacka$$withawrench]

It seems to me that you could have a very energy-efficient car by have a small electric motor and a transmission. You wouldn't need to carry that huge motor coil for torque, just spin the motor to 28k rpm. Using a high amperage and a low voltage and gearing that up, you could have a much safer ev, potentially running it off of SLA or other batteries that are less environmentally harmful no? I want y'alls input on why this isn't possible, or at least why its not being done.

 

[BaconBitRacing]

Electric motors put out peak torque at 1rpm. Plus, some EVs have trannies. The Porsche Taycan has a two-speed. FA can answer this question far better than I can.

 

[Jacka$$withawrench]

Electric motors put out peak torque at 1rpm. Plus, some EVs have trannies. The Porsche Taycan has a two-speed. FA can answer this question far better than I can.

Right. So, just like a diesel, put a bunch of short range ratios together, and you can have a small, low rpm, torquey motor drive a car.

 

[panchothedog]

I never heard the complete explanation ( wasn't that interested ) but a while back, when Tesla made it's first car, a small two seat sports car, they unsuccessfully experimented with trying to incorporate a shifting transmission into the vehicle. For some reason ( which I don't understand ) a transmission works much better when attached to an internal combustion engine. With the amount of money and research that has been invested in E V's if it were doable, I'm quite certain it would be in production.

 

[Denny]

It’s doable just not needed is all.

 

[Jacka$$withawrench]

It’s doable just not needed is all.

Its not needed if you run a big motor on a big car. I'm asking if a FWD single, small electric motor with gears could make up the difference of the torque of a much larger motor, the advantage being you can run it on less amperage.

"Can you make a more efficient EV by using a gearbox?"

 

[BaconBitRacing]

Its not needed if you run a big motor on a big car. I'm asking if a FWD single, small electric motor with gears could make up the difference of the torque of a much larger motor, the advantage being you can run it on less amperage.

"Can you make a more efficient EV by using a gearbox?"

Truth is nobody wants that complexity and no buyer in the electric car market wants a car rated at 60hp.

 

[Jacka$$withawrench]

I thought part of the sales gimmick is that electric is more efficient? I don't know much about selling cars, but if you have 200 mpg equivalent, I feel like that would sell to Prius owners, no?

 

[Jacka$$withawrench]

Found this statement on an old car and driver article:
"Getting a two-speed transmission to work reliably on a powerful electric car is no small feat, as Tesla has found out the hard way." Maybe the instant torque is a shock load to gears?

 

[Functional Artist]

IMO the simplest way to explain it is...

1.) Engines (gas or diesel) usually have to "run" or "idle" before being used
...& so, need a separator (clutch/transmission) for engaging or applying the power to the wheels

2.) Most engines have a very narrow usable "power band" (0 RPM's to at least 1,000 RPM's are usually unusable)
...so, a transmission is used to "spread" that "power band" over a wider range of speeds

Whereas, electric motors don't need to be "running" before use
...so, they don't need a "power separator"
...& have usable torque/power from 0 RPM's, all of the way thru their max RPM's

 

[Jacka$$withawrench]

Whereas, electric motors don't need to be "running" before use
...so, they don't need a "power separator"
...& have usable torque/power from 0 RPM's, all of the way thru their max RPM's

Doesn't an electric engine's torque and power drop off in higher RPM range? If it does, would it make a difference in efficiency to keep the electric motor at 1000rpm and gear up?