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It occurred to me that regen braking contributes to accident avoidance in some small way. In an ICE vehicle, the time it takes to lift one's foot off the accelerator and press the brake to the point where the calipers start to engage in an emergency stop, the vehicle travels some distance depending on speed and reaction time. In an EV, the moment you take your foot off the accellerator braking starts, thus resulting in a shorter distance to stop than in and ICE vehicle. One more reason to dirve an EV and justification for lower insurance rates!
 

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Also the brake lights come on when you start to slow down if I am not mistaken. Compared to say a manual transmission car the lights come on much sooner.
 

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That's why I tend to drive on highway in D, instead of L. Regen braking in D is more like a car with gasoline engine. In L, I will have to keep stepping on the accelerator and tapering off.

-TL

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In an EV, the moment you take your foot off the accellerator braking starts, thus resulting in a shorter distance to stop than in and ICE vehicle.
I've heard people make this argument many times, but in truth you don't get full regen the instant you lift your foot from the accelerator. It takes perhaps half a second to fully ramp up, longer than it takes to move your foot over in an emergency. I'm pretty skeptical that you'd get very much difference in stopping distance. It would be an interesting experiment to compare stopping distances from a given speed in "N" (which eliminates regen) vs. "L" mode.

I think that the emergency auto-braking feature will probably end up being more instrumental in reducing the frequency and severity of accidents. I actually had it engage on me once and it braked more aggressively than I would have done in the situation.
 

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In an EV, the moment you take your foot off the accellerator braking starts, thus resulting in a shorter distance to stop than in and ICE vehicle. One more reason to dirve an EV and justification for lower insurance rates!
Only if the said EV in question is in a one-pedal driving mode, e.g. Bolt's L mode, or have the regen level set to high, e.g. level 3 on Hyundai/Kia EVs. Many people I've seen avoid these modes because they are not yet used to or don't like the way deceleration takes place via regen, which is certainly different from using a mechanical braking system. Given that, I'm not sure if the insurance companies are going to take this into account even if there are benefits to be had.

In terms of how much help the L mode's aggressive deceleration kicking in provides at the time of emergency, it depends a lot. If you were actively braking yourself, the split-second time during which your foot is off of the accelerator and before it's on the brakes is going to provide negligible additional deceleration. However, if you were on the cruise control with L mode and the collision warning system goes off while not paying good attention yourself, then the car would disengage the cruise control to let the L mode's regen kick in even before you make sense of the impending contingency and work the brakes yourself. Emergency auto-braking does not engage at speeds above 80km/h, so on a highway driving this L mode regen is a sort of poor man's version of it. This may make all the difference between an actual collision and a close call. and this I've had personal experiences with both types of cases.
 

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I would rather say it is the other way around.
The brake lights do not light up before regen is into quite decent power.
Even in D, when coasting, it slows down considerably, yet the lights stay off.

In petrol car - most of them coast quite freely, so in any case when you start really slowing down, the brake lights will illuminate first warning cars behind you are are ABOUT to slow down.
I repeat, ABOUT TO. Brake lights are not to let someone know you are stopped, but rather you are about to slow down and eventually stop.
Just like blinkers. They indicate your plan, attempt to make a turn, not the turn itself. When I see car already turning I know what is happening. Hence, the blinker must be used before the turn.

So for avoiding collision only because your car slows down rapidly - eh, big stretch.
In any emergency situation the fraction of a second when regen starts working before regular brakes makes no difference.
I'd even risk saying that EVs have a higher chance of a collision than ICE cars.
Mechanical (friction) brakes depend on the brake pad adhesion to the rotor. If the pad is COLD, there is not much of a friction. It must warm up a bit to start depositing itself on the rotor (sticking to the rotor) in order to give full braking power.
ICE cars use brakes much more often than EVs; hence, when EV suddenly must use pads, they are cold and will not present full performance as ICE's would.

Also, before anyone starts talking about regen here.
Regen is disabled when ABS kicks in. And that is most of the time emergency braking.
 

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It must warm up a bit to start depositing itself on the rotor (sticking to the rotor) in order to give full braking power.
ICE cars use brakes much more often than EVs; hence, when EV suddenly must use pads, they are cold and will not present full performance as ICE's would.
That doesn't sound right to me - brake power fades when the rotors heat up, so on the surface I'd expect them to have maximum effectiveness when they're cold. Do you have a source for this?

Also, unless you're in stop-and-go traffic where you're using the brakes a lot they'll cool off fairly quickly. If you're on a free-flowing Interstate then by the time you've gone a few miles they're going to be at pretty close to ambient temperature.
 

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That doesn't sound right to me - brake power fades when the rotors heat up, so on the surface I'd expect them to have maximum effectiveness when they're cold. Do you have a source for this?
No no no, you are taking it too far.

I will look up some reference for it, but almost all brake pads manufacturers will say that if they carry more than "standard" pads.
For example: normal pads are good at almost right away and take fine a few stops. Also they are OK to take 2-4 emergency stops from 60 mph to dead stop. However, racing pads need to warm up (hence they squeak so much when cold) to be efficient and while the first two stops will be poor, 4th and up will be much better. Those will take 6+ emergency stops.

The fade you are thinking about is more like riding brakes.

Ever heard of pads bedding?
This is a process that should be done for fresh brake system installation (pads and rotors/shoes and drums). The idea is to slowly warm up the pads this much as they are close to fading. They will start "melting" away and depositing on the rotors.
The point is to cover the rotor with pad material that helps create friction.
As you see pads are the main item wearing down. This is due to the fact they actually sort of stick to the rotor. Similar idea is with a rubber eraser (exaggeration).

So, think of it this way.
If you use L to drive and never touch the brake, pads will be covered with dust, grim, rust. Same rotors.
Pads never warm up properly in EVs.
And in the sudden moment - all of this must clear out to produce good braking force...

As for them being warm - I am talking about 50-60 C warm across the whole pad. Each time you slow down, the surface of the rotor and pad will be easily at 200 C and quickly cool off (just like you said). But the whole rotor will be warmish (say 50-60). And clean.


EDIT.
References
Look for this:
What makes a "track" brake pad different from a street pad?


I do not remember the brand where I read a very nice article about pads and their temperatures.
Yet this above gives a rough idea.
 

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However, racing pads need to warm up (hence they squeak so much when cold) to be efficient and while the first two stops will be poor, 4th and up will be much better. Those will take 6+ emergency stops.
Who's talking about racing pads? We're talking about regen and emergency braking, the assumption is that we're using stock pads, isn't it?

Ever heard of pads bedding?
Who's talking about breaking in new pads and/or rotors? We're talking about normal cars in normal service.

If you use L to drive and never touch the brake, pads will be covered with dust, grim, rust. Same rotors.
Pads never warm up properly in EVs.
And in the sudden moment - all of this must clear out to produce good braking force...
All I can tell you is that I drive in L mode all the time and probably only a few times a month do I have to stop more quickly than full L+paddle regen allow. And rarely (maybe a handful of times times a year, if that) do I have to make a panic stop. Yet I've never had any issue locking up the wheels when I've had to do it. I stomp on the brake pedal, the wheels lock up, and ABS does its thing.

I'm not a racer, just a normal everyday reasonably cautious driver. Maybe there are some subtleties to race driving that escape me. But in terms of what the average motorist should expect, nothing about my experience with the Bolt suggests that its brakes are in any way less effective than any of the other cars I've driven.
 

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nothing about my experience with the Bolt suggests that its brakes are in any way less effective than any of the other cars I've driven.
I find it opposite.
I tried a few sudden stops (just to feel them) and the first one did not engage ABS until about 3/4 of the stop going from 55 mph to 5 mph. Tried that again another day and same result. 3rd stop was the best.
They seemed like they were not warm enough.

The info above and examples including racing pads - that is all to show the concept and give the reader background information on brakes and how they work with emphasis on the part that pads need to warm up to operate at their full. It is not to claim Bolt has racing pads or such. You just took it way too far.. :)

Speaking of which - we drifted off the topic here.


I will still say - any EV with regen braking would rather increase possibility of rear ending due to late activation of the brake lights. I found myself a few times behind Volt that would start slowing down more rapidly than expected, yet the lights remained dark.
 

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As to insurance companies and braking for accident avoidance, there is the history for anti-lock brakes to illuminate the subject. When they were first introduced, many insurance companies offered a reduction in premiums for them. The data didn't show the expected benefits. Most drivers never learned to use the anti-lock benefits and even panicked when the pedal began to pulsate and took their foot off. Those who learned to use it drove faster, followed closer and braked harder, using up the margin of safety.

There are probably fifty threads on variations of the Bolt regenerative braking and they seem to be all opinion, pro or con; no data to substantiate any of it.

Those of us who use L exclusively think the one-pedal is the unique feature of the Bolt and cannot imagine why anyone would not see it as a benefit.

There are a substantial minority who are paranoid about the brake lights not staying on when stopped, don't like that L requires precision control of the one-pedal, those who still think hypermiling coasting can work with a BEV, those who don't understand disc brake pads ride against the rotors all the time, thus keeping them clean and ready for use, et al.

Since three years and counting this discussion goes around and comes around yet again, without data, but with the same opinions being offered yet again, it's unlikely ever to change anyone's stance. Your Bolt; drive it as you will.

jack vines
 

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Say I am driving on a highway at 65mph in L. I let go the accelerator for some reason. The car will decelerate much faster than a normal car in the same situation, which is expected to the traffic behind you, even the brake light turns on immediately. This sort of unexpectedly behaviors will likely cause accident. That's why I drive in D on highways.

In a traditional car, the brake light turns on by a switch activated by the brake peddle. It won't turn on if I don't step on the peddle, say shifting to low gear, pulling the parking brake etc. In bolt, measured deceleration is one of the mechanisms to turn on the light.

Maybe we should put ourselves in the seat of other motorists, and try not to behave unexpectedly.

-TL

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Maybe we should put ourselves in the seat of other motorists, and try not to behave unexpectedly.
Excellent advice, and I'll add that we shouldn't follow too closely to the guy in front of us either. Who knows, maybe his brake lights are burnt out like the guy I was following this morning.
 

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Well... the pads do not touch the rotor all the time. If that was the case you'd not have wet rotors (when driving in rain), yet they are always wet and first braking after a longer drive is very weak.

In very short I will reiterate what I said.
Pads and rotors need to be at certain temperature to work efficiently. It might be small difference for some cars, larger for others.
All ICE cars I had were about same way - 1st harder braking was OK, but 2nd or 3rd seemed much "grabbier".
Therefore, if brakes are constantly cold on EVs, it would have even larger effect.
No, I do not have empirical data.

To reflect on the posts above.

When I hear people saying they need to buy SUV because they are safer, it makes me want to shake them.
The car is as safe as its driver. No systems can replace good driver. Expect unexpected.
I learnt handling without power steering, ABS, and on some cars even without brake booster. Purely mechanical - you brake as hard as your foot can push.


Final note about erratic behaviour.
I completely agree. However, the L mode. Yes, the brake lights DO light up, but the initial slow down they do not. Even if you lift off the fool completely, the initial braking force will not trigger them. It may seem short, but if you are in traffic and cars are close to each other going about 30 mph, such delay is quite large.

I looked how quickly the lights light up.
My trailer has a "control lights", small LEDs that are facing forward. There are 3 of them - amber turn signal, red position, and red brake. Control lights, because I can see them in my mirror, so I know if the trailer lights are active or not.
The thing is that whenever I tried L, I noticed quite long delay before they would kick in.

Some say - any MT ICE car would act same. I do not agree. All ICE cars I had recently, coasted much easier in almost any gear (except 1 or 2) than Bolt in D. Not to mention letting off the gas when in tallest gear going, say, 50 mph. It seems like Bolt puts brakes on, while my Forte5 SX would roll... same Elantra. Q5 - this one rolls the best (8sp AT).


One last comment to packard V8.

Yes, coasting in BEV (if it was just free coasting, not regen) helps. I personally would prefer if the car just coasted like in N when I lift off foot of the pedal and regen when I start pushing the brake pedal.
If you were to accelerate and let it coast till it stops vs cover same distance in driving and then regen braking, the net energy used would be less with coasting situation as recharging the battery is about 70% efficient.
Yes, the overall gain would not be large, yet probably same level as driving in D vs in L mode.
 
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