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Tires and brake disks/pads aren't cars. If the chemicals that make them are so dangerous, why not focus on replacements? Last I checked, bicycles have tires t
by dade_ 9y ago
Tires and brake disks/pads aren't cars. If the chemicals that make them are so dangerous, why not focus on replacements? Last I checked, bicycles have tires that wear out too.
- paganel 9y ago> Tires and brake disks/pads aren't cars. I think they're part of a car, aren't they? I mean, you cannot drive a car with no tires, and it's advisable that you should also have brake disks/pads.
- Lio 9y agoWell with regard to brake discs/pads I'm surprised that the electric car manufacturers are working towards a fully regenerative system. If you could return all of the forward momentum as energy to the battery that would remove the need for discs and pads.
- mikeash 9y agoMechanical brakes have two major advantages over regenerative braking. One is that they can handle extremely high transient power levels. For example, maximum-effort braking at high speed can easily involve over a megawatt of power in the initial stages. Dumping that power into your brake pads and rotors as heat is fairly easy to manage. Dumping that into your battery without wrecking it is much, much harder. For comparison, a high-end Tesla can charge at up to 120kW, and can discharge around 600kW in short bursts. The other advantage is that they're cheap, reliable, and can easily be built with redundancy. You can lose all of your car's computers and half of your brake hydraulics and still be able to stop the car. In order to have no mechanical brakes at all, you'd need a battery that could charge fast enough to absorb the power of full braking at maximum speed, and a sufficiently redundant drivetrain that you could still make regen work even if major components failed.
- skybrian 9y agoAgreed. On the other hand, the brakes on a Prius are used much less. If pollution due to wear is an issue, that should help.
- mikeash 9y agoDefinitely. If pollution is the concern, there isn't much difference between not having mechanical brakes and having mechanical brakes you rarely use.
- gozur88 9y agoBut the important thing isn't that the mechanical brakes exist, it's that they get used. Presumably with computers driving cars and regional coordination, you would have cars doing mostly regenerative braking and reserve the mechanical brakes for emergencies.
- mikeash 9y agoIndeed, and this is more or less how it is already. Hybrid and EV drivers report their brakes lasting far, far longer.
- erikpukinskis 9y ago> Dumping that into your battery without wrecking it is much, much harder Use capacitors?
- Coincoin 9y agoThat's why mega capacitors are so interesting even if they can't store as much as a battery. We could instantly store all current kinetic energy in it and then recharge the battery "slowly" with the energy from the capacitor. I agree about your second point, mechanical brakes are very simple and reliable. I'm pretty sure we will forever have them in our cars for safety/emergency reasons.
- deckar01 9y agoAnd designing mechanical systems that don't produce so much friction.
- zython 9y agoAny idea why its called bicycle and not quadcycle ? The wear and tear on tires and bikes with a 100kg system weight is much less than car to say the least.
- xiphias 9y agoAlso the linked paper doesn't take regenerative breaking of electric cars into account.