Eli5 why electric cars don’t have smthn like reverse thrust while braking (wheels spin backwards in hard braking situation)
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Many do use the motors to recapture power which does slow the car. It’s very effective and reduces brake wear to the point Teslas need their brakes greased every 6 months because they’re used so little.
You don’t want opposite tire spin because once you’ve broken traction, you have no directional control. If you’re doing 70mph, you don’t want your tires spinning freely while in a panic as the maximum rate of slowing is limited to the tire’s traction.
Because that would just make the wheels lose traction, causing the card to skid uncontrollably rather than stopping.
You know “reverse thrust” on a plane doesn’t make the landing gear wheels spin backwards, right?
When your braking, you don’t wan’t the tires to slip on the road surface and start spinning. It’s less efficient and wears out your tires much quicker.
The problem is that the larger the difference between the tire speed and the road speed, the less grip you have. Eventually the tire will melt and you will just glide on melted rubber.
Inversely this is also why, while burn out is fun, it is not the best way to launch the car.
Gas cars also don’t have the “backward wheel spin” that you’re suggesting could be “reverse thrust while braking”.
And like the other person said, if a car did that then it wouldn’t make sense because it would mean the wheels lost traction.
Your wheels generate the most force when they are *just barely slipping*. If you graph the two, it looks something like [this](https://www.hondata.com/help/tractioncontrol/wheelslip.gif).
When you slam on the brakes, you want your wheels to just barely skid. Too much skid means you get *less* traction. Spinning the wheels the whole wrong way means *even more skid*.
In a traditional car you’d have an ABS system to ensure that your wheels get the right amount of skid. Teslas have even more advanced systems, and other electrics may as well. These get the best possible traction, which again, means almost no slip.
Electric cars have a more efficient way to help quickly slow the vehicle down. In a very over simplified terms, the same stuff that turns electricity into motion of the car can work in reverse and turn motion of the car into electricity.
Electric cars have a combination of traditional breaks as well as energy recovery. The electric motor can harvest electricity from the wheels slowing down the car and this is actually more effective at slowing a car down than the breaks.
Spinning the wheels backwards is possible with the torque a car has, but it wouldn’t help. This would just cause the tires to lose traction and make the car impossible to control, increasing the changes of a big accident.
They do. It’s called regenerative braking. By sucking power out of the electric motor instead of putting it in, they can reverse the torque spinning the wheels; the motors push backwards. This stops the car from moving even faster than traditional friction brakes. And the big bonus is they can capture that energy. Put it back in the battery to use for moving forward again later. That’s why it’s called regenerative braking.
Electric cars have a more efficient way to help quickly slow the vehicle down. In a very over simplified terms, the same stuff that turns electricity into motion of the car can work in reverse and turn motion of the car into electricity.
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