Small disc brakes?
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Remember, regen provides part to all of the braking done by EV's.
10 to 11 inch rotors are common on EV's and these fall on the high side. (11 in is 279 mm). These are bigger than on the Spark EV, but slightly smaller than the LEAF. The BMW i3 is 11" front and rear.
10 to 11 inch rotors are common on EV's and these fall on the high side. (11 in is 279 mm). These are bigger than on the Spark EV, but slightly smaller than the LEAF. The BMW i3 is 11" front and rear.
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862 Posts
Huh???
Just because there is a patent doesn't make it practical.
If you take an average of 4 miles/kWh, you would need to recover 1 kWh to gain 4 miles in range. What could you possibly gain? .5 miles?
If current EV's are losing 1% of their range to heat generated in the dampers, you could add <1 mile of range. There is absolutely no need for heat management (remote resevoirs, etc) in anything but very high performance vehicles used in situations like racetracks. If there is not waste heat being generated, there is nothing to capture and convert to energy to charge the battery.
Granted, there is some small amount that could likely be gained, but the added cost and complexity is not anywhere near worth the gain (even more so as battery costs drop). Your gonna add what, .1% to the range? At what cost ($ and weight)?
Regeneration sizing verses "panic" needs for brake sizing?
As I get older my following distances are increasing as my reaction times decrease. But sure as the sun rises in the east someone will pull in the space I leave requiring me the brake.
What is the consensus of opinion of all the experienced EV owners here?
As I get older my following distances are increasing as my reaction times decrease. But sure as the sun rises in the east someone will pull in the space I leave requiring me the brake.
What is the consensus of opinion of all the experienced EV owners here?
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172 Posts
I doubt that you'll see a consensus, but I've never felt that my Leaf has inadequate brakes. There are other issues with them, like the ABS reducing braking too aggressively under some road conditions, and losing power assist if the 12 volt accessory battery fails, but when the full stopping power of the brakes can be used, it seems quite adequate.What is the consensus of opinion of all the experienced EV owners here?
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118 Posts
41 Years of EV Experience
After 41 years of EV experience with different EVs, when regeneration is used frequently the less the brakes become used, almost like muscle memory. The inexperienced EV driver may use both often, but as the experience with regen lengthens, the brakes become rarely even tapped. The more the driver can control this the quicker the learning curve.
I look forward to the Bolt experience!
After 41 years of EV experience with different EVs, when regeneration is used frequently the less the brakes become used, almost like muscle memory. The inexperienced EV driver may use both often, but as the experience with regen lengthens, the brakes become rarely even tapped. The more the driver can control this the quicker the learning curve.
I look forward to the Bolt experience!
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786 Posts
I have seen how brake rotors have become smaller after servicing many GM and Ford cars since 1975. My 1995 Buick Regal had 11-inch rotors, yet never gave me problems in 21 years of service. As a fact, the pads lasted long, as they were changed only twice in those 21 years (the dealer did it once and I did the second one at home). My present 2009 Chevy Equinox also has small brake rotors yet it also stops perfectly after eight years (still has original pads!).
I expect the brake systems to get smaller (and weigh less) with hybrids and electrics because the motor regeneration will do most of the "speed reduction" (action) until the last few feet (or meters) where the hydraulic brakes come in. That is only low speed braking and you need less effort and materials to do that. As a side benefit, the wheel weight is less, the cost of pad replacements will drop, and the rotors will last the life of the vehicle. The only exception will be if the driver does many "panic stops" due to terrible driving, not good for any vehicle either gas or electric!
Extra: There is a prototype high speed car, made from the fuselage of the F-104 supersonic jet fighter, that will try to break the British car's record as the world's fastest car. The brakes are actually inductive, using a pair of aluminum rotors (one fixed on the body and the other on the axle) that generate a huge eddy current, and an induced and opposing magnetic field at high speed when the rotors are pressed together, producing the reverse torque needed to stop the car so that it has no hydraulic brakes and doesn't need a parachute, either. It is called the "Eagle".
I expect the brake systems to get smaller (and weigh less) with hybrids and electrics because the motor regeneration will do most of the "speed reduction" (action) until the last few feet (or meters) where the hydraulic brakes come in. That is only low speed braking and you need less effort and materials to do that. As a side benefit, the wheel weight is less, the cost of pad replacements will drop, and the rotors will last the life of the vehicle. The only exception will be if the driver does many "panic stops" due to terrible driving, not good for any vehicle either gas or electric!
Extra: There is a prototype high speed car, made from the fuselage of the F-104 supersonic jet fighter, that will try to break the British car's record as the world's fastest car. The brakes are actually inductive, using a pair of aluminum rotors (one fixed on the body and the other on the axle) that generate a huge eddy current, and an induced and opposing magnetic field at high speed when the rotors are pressed together, producing the reverse torque needed to stop the car so that it has no hydraulic brakes and doesn't need a parachute, either. It is called the "Eagle".
Add to that the growing amount of lanes for green vehicles/car pooling/etc. and it gets even better since then the lanes we're in are much smoother and no where near as congested as regular lanes. One of the reasons i can't wait for self driving cars to be on the road in mass.
Good point, there was some news on it once and then all of that disappeared with no mentions of it in publications and the usual sources.
Anyways, back to the brakes, anyone considered about how regen will perform on roads in poor conditions? I have seen owners of the i3 reporting on it and an i3 owner I randomly spoke to in person attested to that
Anyways, back to the brakes, anyone considered about how regen will perform on roads in poor conditions? I have seen owners of the i3 reporting on it and an i3 owner I randomly spoke to in person attested to that
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