I know electric cars don’t need multiple gears, but wouldn’t they benefit from them in anyway at high speed for example?
In: Technology
Early electric cars DID, they didn’t perform well without them. An electric motor with a fixed gearing so it doesn’t fly apart at 85 mph would be so weak at 5mph that it would burn itself up and produce very little torque.
But a transmission does create some losses, is a really common/expensive point of failure (I think most gasoline cars eventually have a transmission failure before major engine thing like a seizure), they’re super expensive to design and build, and add weight and bulk to the drivetrain that could be used for more motor or battery.
IF you can shrink or avoid a transmission, it’s usually a good thing.
No. An internal combustion engine has low torque and low efficiency at low RPMs and at high RPMs. Gearing is needed to keep it in the sweet spot so the engine does not bog down.
An electric motor has it’s highest torque at low RPMs and it’s highest efficiency somewhere around 70% (ballpark) of it’s highest RPMs. Once you hit the “highest” RPMs, you can do additional electrical/mathematical magic that sacrifices efficiency for more RPMs.
The problem with gearing is that each gear-pass is maybe 98% efficient if you are lucky. So introducing any gearing at all reduces an electric motor’s efficiency more than what is gained by doing the electrical/mathematical magic when it is needed in extreme and uncommon scenarios.
In some instances yes. CVTs are great for DC motors, but it’s all dependent on the type of motor being used and if you gain enough efficiency to be worth the added weight.
They benefit from different transmission ratios despite not as much as internal combustion engines. There are even two gear transmissions for electric cars available: https://press.zf.com/press/en/releases/release_10181.html
Electric cars are geared. Their Continuously Variable transmission (CVT) gives them a virtually infinite gear set.
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Electric cars also have gears but the change is rather performed by adapting electrical parameters, e.g. phase in relation to rotation of motor
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