3 ms·

Because that's not how batteries work. Regen works because the batteries are being charged by the induction of the motors taking energy from the moving car. If

Because that's not how batteries work. Regen works because the batteries are being charged by the induction of the motors taking energy from the moving car. If the batteries are full they cannot take any more change and hence cannot draw power from the motion of the car. What do you expect them to do? Dump the current on a giant resistor and hope it doesn't melt?

LadyCailin 6y ago
Simulate the same braking curve with the physical brakes as when regen is functioning?
dodobirdlord 6y ago
I suppose that's one approach. Mechanical brakes work by converting the kinetic energy of the vehicle into heat via friction, it seems fitting that inductive brakes would dump energy to heat by running current over a resistor. Though under normal braking circumstances I don't know what percentage of the vehicle's energy is lost to the brakes themselves and what percentage is lost to the friction of the tire with the road.
10000truths 6y ago
> Dump the current on a giant resistor and hope it doesn't melt? That's called an induction brake and it's already widely used in trains and semi trucks. That said, you still need a friction brake at low speeds, since the induction braking force is proportional to velocity.
JohnJamesRambo 6y ago
Can anyone do the math and tell me how big that resistor would need to be? I’ve always wondered how many watts are being dissipated by my brake pads and rotors when I stop.
- saagarjha 6y ago
  Assuming your Tesla is around 2000 kg and traveling at 30 meters/s, it's got about 900,000 J of kinetic energy. Stopping in 10s is some serious power that you'd need to throw off.
  - fulafel 6y ago
    All of yhe 90 kW doesn't need to be radiated in real time though as it's ok for the brake elements to heat up.
vagrantJin 6y ago
> What do you expect them to do? Dump the current on a giant resistor and hope it doesn't melt? You know...they could use it to boil water for a built in coffee/green tea maker. Just a thought...

LadyCailin 6y ago

Simulate the same braking curve with the physical brakes as when regen is functioning?

dodobirdlord 6y ago

I suppose that's one approach. Mechanical brakes work by converting the kinetic energy of the vehicle into heat via friction, it seems fitting that inductive brakes would dump energy to heat by running current over a resistor. Though under normal braking circumstances I don't know what percentage of the vehicle's energy is lost to the brakes themselves and what percentage is lost to the friction of the tire with the road.

10000truths 6y ago

> Dump the current on a giant resistor and hope it doesn't melt? That's called an induction brake and it's already widely used in trains and semi trucks. That said, you still need a friction brake at low speeds, since the induction braking force is proportional to velocity.

JohnJamesRambo 6y ago

Can anyone do the math and tell me how big that resistor would need to be? I’ve always wondered how many watts are being dissipated by my brake pads and rotors when I stop.

saagarjha 6y ago
Assuming your Tesla is around 2000 kg and traveling at 30 meters/s, it's got about 900,000 J of kinetic energy. Stopping in 10s is some serious power that you'd need to throw off.
- fulafel 6y ago
  All of yhe 90 kW doesn't need to be radiated in real time though as it's ok for the brake elements to heat up.

vagrantJin 6y ago

> What do you expect them to do? Dump the current on a giant resistor and hope it doesn't melt? You know...they could use it to boil water for a built in coffee/green tea maker. Just a thought...