OT: Brakes seizing on electric cars? (2024 Update)

[Commander Kinsey]

I slow down more rapidly, I like to get where I'm going fast and have fun doing so. How rapidly can you decelerate on regen only?

[Commander Kinsey]

I slow down more rapidly, I like to get where I'm going fast and have fun doing so. How rapidly can you decelerate on regen only?

[Commander Kinsey]

Nothing you've said seems to suggest it's a misleading term.

Why on earth would you change down? Extra effort. I just stop with the brakes, push in the clutch when I'm going too slow for 5th, then pick a gear when I'm about to accelerate again.

I've only used a low gear once, coming down the French Alps, and only because I could smell brake.

Actually another time, I scared the passenger by selecting 1st in an automatic at 100mph.

[Commander Kinsey]

Nothing you've said seems to suggest it's a misleading term.

Why on earth would you change down? Extra effort. I just stop with the brakes, push in the clutch when I'm going too slow for 5th, then pick a gear when I'm about to accelerate again.

I've only used a low gear once, coming down the French Alps, and only because I could smell brake.

Actually another time, I scared the passenger by selecting 1st in an automatic at 100mph.

[NY]

I tend to think of regenerative braking as doing something *useful* with the kinetic energy that is converted to electricity: feeding it back into the grid with trains/trams, or feeding it back into the batteries with battery electric cars.

Feeding into a huge resistor is still regenerative, but it is a waste of the energy unless it helps heat the inside of the car on a cold day.

I imagine that battery EVs feed as much power into the battery as they can (subject to an upper limit on how quickly batteries can be charged) and any excess is dumped to a resistor.

If a car is slowed from (for example) 70 mph to rest at a brisk but not emergency level of braking, what proportion of the energy (roughly) is converted back to useful energy in the battery, and what proportion goes as heat. Assuming braking is by regeneration to the maximum possible level, with the minium frictional braking that is needed.

Is there any noticeable discontinuity if the brake pedal is gradually pressed to increase the braking force, as the system switches (gradually?) between regen and frictional? Does it "feel" like pure frictional braking, or does the driver have to get used to a sudden change as he gradually increases the brake pedal pressure.

[NY]

I learned in the early 1980s, at a time when changing down sequentially was still required to pass the normal test. Changing to a lower gear on a lower gear on a long gradual downhill was still taught. On a 1:3 hill (eg Rosedale Chimney, near where I live) I tend to change into second for a bit of additional retardation over and above the braking, but I imagine with disc brakes, there is less chance of the brake pads heating up to the extent that they lose braking force.

My wife remembers many years ago coming down Porlock Hill (long, steep) in Devon in a small motor caravan (Bedford Bambi, which may have had some drum brakes) and the driver remained in top gear and used only the footbrake, and the brakes started to fade, so she had to tell the driver to get into second gear as fast as possible.

My dad had an automatic Ford Corsair in the late 1960s and he once had it go into first of its own accord (ie he didn't move the shift lever) at motorway speed (60-70 mph) which knackered the transmission and probably over-revved the engine although without a rev counter it's difficult to judge what engine speed it got up to. He said that the retardation when he instinctively came off the power was tremendous: he had to apply a bit of accelerator to prevent the mechanical load of the engine on the wheels (via a low gear) locking the wheels. I suppose he should have gone into neutral to avoid over-revving the engine.

[Bob Eager]

It doesn't feel any different to me. And there is a bar graph that tells me how hard I can brake before I start wasting the regeneration.

[Bob F]

Does that distract you from watching what's going on around you?

[Paul]

The brake blending on at least one of the BEVs was bad. There was a noticeable gap between regen portion of pedal and friction brake.

Many others, perhaps using more fly-by-wire, are "perfection".

There are different motor types. At least, Permanent Magnet and Induction motors, as examples. Some cars have two motors, one for the front axle, one for the back axle, and the motors aren't even the same type. The regen characteristics are different for each.

A motor that requires "excitation", would waste battery energy if you regenned at 5 kph. That's part of the reason some of them stop regen at speeds like 30 kph. The motor definitely regens, but, it may not be economical of battery life, to do that below 30 kph.

Cars have been made, with 1,2,3, or 4 motors. They've tried it all :-)

But an overall message is, they've made the same "complexity mistakes" as the ICE vehicles. There was an opportunity to "simplify" and it took about ten microseconds to throw that idea out the window. I hold out hope for the "city cars", that they may preserve some of the spirit of simplicity. The porkers they're making now, there is way too much stuff to break down on them, for their own good.

Ford right now, has discovered after their first generation of BEV, that "there are too many miles of wire in the chassis". They need to do another kind of control bus, to reduce the control complexity inside the vehicle, and reduce manufacturing costs. And that's just for all the computers in the machine. You didn't hear them say "we need to reduce the number of computers". Instead, they're saying "we need to make the wires more efficient, between all these here computers". When all the indicator lights in your dash, flash on and off, your mechanic goes "f*ck me, an electrical problem". They hate those (my brother is a mechanic and admits this). Now, imagine working on a car, where the car maker admits "there are too many miles of wire in here" :-)

Paul

[Bob Eager]

Not really. Doesn't take long to learn what happens and just do it anyway. Same applies to the other end of the bar that indicates when it's going to actually use the engine.

[Commander Kinsey]

It would have been impossible to lock the wheels, this would have meant the engine was not rotating at all.

I guess you meant skidding, when the wheels rotated slower than the car was moving.

[Vir Campestris]

<snip>

More recently than that I had a last model Vauxhall Cavalier as a company car. It developed a vibration which turned out to be because the front discs had warped.

The next time I went to the same site in it and went down the same long steep hill, it developed the same vibration and needed another set of discs.

Andy

[soup]

Because they are made of cast iron rater than steel. So rust VERY quickly.

Discs used to have lots of asbestos in them which wasn't good for peoples lungs, and they used to get a thin film of pad material on them which inhibited corrosion, so the rust is more noticeable these days . Not to worry though the rust is 'scrubbed' off very quickly and the retardation is not affected. Then new rust is formed within hours.

For speedy corrosion nothing (?) beats Aluminium all Aluminium is covered in a V thin coat of Aluminium oxide scrape this away to reveal pure Aluminium underneath then watch as the 'scratch' turns from very shiny to a dull shine before your very eyes as more Aluminium oxide is formed. It is said that Aluminium doesn't corrode but it does and very quickly however the Oxygen can't make it through the Aluminium oxide so only a very thin layer of the Aluminium oxidises then the bulk of the material is safe under its coat of oxide.

[SteveW]

You're attributing the quote to the wrong person - that question was posed by Commander Kinsey, in response to my earlier post.

[SH]

All disks are coated in rust, how else do they store the binary 1's and 0's?

You could replace the HDD with a SSD to become free of rust.....

[Bob F]

It was quite clear to me who he was responding to.

[The Natural Philosopher]

[Commander Kinsey]

Why do you say BEV? All EVs are battery. A hybrid is not an EV.

Howe can it not be good for battery life to give it a little trickle of power?

I want the good old days of a basic Citroen 2CV or Lada Riva. Cheap and nasty but it works and is easy to maintain.

Superfluous word.

That's the mechanic's fault for not taking lessons in electronics. The garage I use says "electrical problem", plugs in a laptop, then orders the necessary part.

[Commander Kinsey]

No it isn't. The word regenerate means to recreate. You regenerate your skin after injuring it. Putting it into a resistor is just slowing the car down and making heat, just like a friction brake, but without wearing the pads.

I wonder if any cars do that? They might also warm the battery. They don't like the cold.

Superfluous word.

Get one and try it, they usually tell you all sorts of shit on the dash.

I wonder why it's called a dashboard? There's no hurry about it.

[Xeno]

You would be wrong. Please educate yourself before mouthing off. Not all EVs are battery. Hydrogen fuel cell vehicles are EVs but they don't carry all their stored power in a battery. They are called FCEV. To differentiate between the tyes, we call one a BEV, the other a FCEV.

When you want to use Lithium Ion batteries, or similar, simplicity is out the window. The charging system needs to be intelligent, you need a battery monitoring system and the battery requires active cooling up to and including its own AC system - not to forget heating.

Want simplicity - back to deep cycle lead acid batteries with limited range but less complex needs.

Sorry, the world has moved on and such pieces of crap are no longer task effective.