Regenerative brake

[whitex]

BTW it is enabled by default for Sport Plus.

Also in Sport, at least in my car.

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[freeforall]

Also in Sport, at least in my car.

In mine, it is not. It is only enabled in Sport Plus. I have a MY23 with Sport Chrono. Do you have Sport Chrono? Maybe when you don’t have Sport Chrono they enable Regen for Sport mode? (I believe that there is no Sport Plus mode when you don’t have Sport Chrono?)

 

[whitex]

In mine, it is not. It is only enabled in Sport Plus. I have a MY23 with Sport Chrono. Do you have Sport Chrono? Maybe when you don’t have Sport Chrono they enable Regen for Sport mode? (I believe that there is no Sport Plus mode when you don’t have Sport Chrono?)

Yes, 2023 Taycan Turbo Cross Turismo with Sport Chrono. Sport turns on recuperation, as does Sport+. I can also manually turn it on/off via a dedicated steering wheel button (which I use when I drive in Normal, typically over rough roads, I still want recuperation).

 

[f1eng]

I don't understand how coasting is more efficient than 1 pedal regen driving.
I drive many other EV's a lot (>50k miles per year) and it is kind of annoying to jump in my Taycan then suddenly find almost no deceleration due to regen.

Your inability to understand does not make it not true

It is clear from tests in racing and, in fact obvious if you consider the engineering.

 

[or1]

I don't understand how coasting is more efficient than 1 pedal regen driving.
I drive many other EV's a lot (>50k miles per year) and it is kind of annoying to jump in my Taycan then suddenly find almost no deceleration due to regen.

Intermittently braking and accelerating is less efficient than just rolling. There is loss to heat in both the regenerating part and the accelerating part. Not a lot of loss, but maybe some 20%.
If you can keep the rightfoot pedal at just the point of coasting (when no speed change is due), then you are as efficient as you can get. But in general that is hard. The coasting point is much easier to get at if it is with rightfoot pedal unused.

 

[SpawnyWhippet]

Your inability to understand does not make it not true

It is clear from tests in racing and, in fact obvious if you consider the engineering.

I don’t really agree. 99% of the time when I lift the throttle it is to slow down, not coast. I therefore want the vehicle to decelerate, not coast.
It can not draw more energy to coast at 50 than maintain 50 with foot on the throttle. Otherwise the vehicle would accelerate - that energy has to go somewhere. The car does not work like a gas car, it does not draw power just because your foot is on the throttle, it draws power when there is torque demand.

Rivian has the blended brake design, works very well, a lot better than Taycan. However Taycan is otherwise nicer to drive.

 

[hifi239]

I don't understand how coasting is more efficient than 1 pedal regen driving.
I drive many other EV's a lot (>50k miles per year) and it is kind of annoying to jump in my Taycan then suddenly find almost no deceleration due to regen.

Yes, it is a different style. Most other EV makers, including Tesla, did not solve the blended braking challenge, and they instead have very simple lift-off regeneration, along with simple conventional brake systems. Porsche went with the much more challenging blended braking solution, where you trigger the regen by pushing the brake pedal, and you get a combination of regen and conventional braking, depending on speed and demanded deceleration. It is partly because that can be more efficient for suburban and rural driving, and partly because that provides more control for spirited driving (I'm told). For stop and go city driving, the one-pedal regen is probably more efficient. The most efficiency on the highway is probably in cruise control mode, where the Porsche will regen on downhills to maintain speed.

 

[SpawnyWhippet]

Intermittently braking and accelerating is less efficient than just rolling. There is loss to heat in both the regenerating part and the accelerating part. Not a lot of loss, but maybe some 20%.
If you can keep the rightfoot pedal at just the point of coasting (when no speed change is due), then you are as efficient as you can get. But in general that is hard. The coasting point is much easier to get at if it is with rightfoot pedal unused.

I don't find it at all difficult to maintain a constant speed going up or down hills, or in city traffic. It's like riding a bike, its just a muscle memory activity. When I hold the Rivian throttle at a percentage where a regular gas car would coast, it does coast, no energy is being consumed. I am not on and off the throttle all the time to maintain that speed and actually, I need more pedal input to maintain a specific velocity in the Taycan than in my Rivian. It's my primary complaint about the Taycan, and the main thing I look forward to in the Rivian when I switch vehicles.

 

[f1eng]

I don’t really agree. 99% of the time when I lift the throttle it is to slow down, not coast. I therefore want the vehicle to decelerate, not coast.
It can not draw more energy to coast at 50 than maintain 50 with foot on the throttle. Otherwise the vehicle would accelerate - that energy has to go somewhere. The car does not work like a gas car, it does not draw power just because your foot is on the throttle, it draws power when there is torque demand.

Rivian has the blended brake design, works very well, a lot better than Taycan. However Taycan is otherwise nicer to drive.

Did you study physics at school?
Seems you didn't pay attention.

 

[SpawnyWhippet]

Yes I did. I have a Bachelors and Masters in Engineering, which is why I understand concepts like the conservation of energy that seem to be eluding you. Maybe you can explain where that energy to maintain the same speed as coasting is going if it is not applying accelerative forces?
I’ll wait… (hint, if the forces are the same, then no energy CAN be getting used)

Once you dig deeper into this, you realize that the regen braking method is just better and more intuitive. The throttle pedal becomes a speed control pedal, instead of a mechanism for regulating fuel consumption. 30% pedal application will give you 30% speed regardless of whether you are going uphill or downhill, rather than 30% fuel consumption, which gives you rampant acceleration downhill and almost nothing going uphill.
eg I could be driving the Rivian down a steep hill with 30% pedal, getting a ton of regen despite being on the throttle. Or in the Taycan, I am on the brakes modulating the pedal all the way.

 

[f1eng]

Yes I did. I have a Bachelors and Masters in Engineering, which is why I understand concepts like the conservation of energy that seem to be eluding you. Maybe you can explain where that energy to maintain the same speed as coasting is going if it is not applying accelerative forces?
I’ll wait… (hint, if the forces are the same, then no energy CAN be getting used)

Once you dig deeper into this, you realize that the regen braking method is just better and more intuitive. The throttle pedal becomes a speed control pedal, instead of a mechanism for regulating fuel consumption. 30% pedal application will give you 30% speed regardless of whether you are going uphill or downhill, rather than 30% fuel consumption, which gives you rampant acceleration downhill and almost nothing going uphill.
eg I could be driving the Rivian down a steep hill with 30% pedal, getting a ton of regen despite being on the throttle. Or in the Taycan, I am on the brakes modulating the pedal all the way.

It is simpler than this.

The regen system is less than 100% efficient so any regen will have to be more lossy than coasting.

We started doing this in Formula 1 even with IC engines, coasting is the most efficient way of using the least energy.

However you want to drive.

If you have a different preference in the way you feel comfortable driving fine. It just won't be as efficient as coasting and frankly I would not have expected it to be difficult for a qualified engineer to understand.

 

[SpawnyWhippet]

You are still missing my point and you evaded my question about conservation of energy.

In F1, 'coasting' means to lift a little sooner and get on the brakes a little later before a tight turn to save a small amount of fuel consumption and/or reduce brake temps. It is not relevant here.

When you are maintaining speed on a very slight downhill in a regen braking car, ie coasting, the regen is by definition NOT active, otherwise you would be decelerating - the vehicle is coasting exactly like a Taycan and using no fuel. Vehicles with good regen braking systems will still allow you to coast as long as you don't lift your foot completely off the pedal, you maintain accelerator position for the speed you want to travel at, hence the regen braking vehicle will not draw power or regen in that coasting situation. I can view this precise energy demand live on my dashboard in my Rivian.
The only difference is that you need to use a second pedal to achieve the braking part of maintaining velocity in a Taycan.
I haven't touched the brake pedal in my Rivian for many hundreds or even thousands of miles, and despite being far bigger, heavier and far less aerodynamic, it is almost as efficient around town, because of the regen system. Yesterday I drove my Rivian 200 miles down a mountain and across California back home without touching the brake pedal a single time. I'd have been on the brakes for 40 miles in the Taycan.

This whole thing to me is no different to the people who bitched about horses being replaced by the first cars, or losing the advance retard controls when that became automated with distributors, or when PDK transmissions became better and more widespread than manual transmissions, or fuel injection replaced carburetors. I've driven tens or hundreds of thousands of miles in both types of EV's and the regen cars were superior and less demanding.
If I want a challenging drive, I will take an entirely different breed of car; if I just want to get there with minimal fuss, I'll take the Rivian.

 

[f1eng]

You are still missing my point and you evaded my question about conservation of energy.

In F1, 'coasting' means to lift a little sooner and get on the brakes a little later before a tight turn to save a small amount of fuel consumption and/or reduce brake temps. It is not relevant here.

When you are maintaining speed on a very slight downhill in a regen braking car, ie coasting, the regen is by definition NOT active, otherwise you would be decelerating - the vehicle is coasting exactly like a Taycan and using no fuel. Vehicles with good regen braking systems will still allow you to coast as long as you don't lift your foot completely off the pedal, you maintain accelerator position for the speed you want to travel at, hence the regen braking vehicle will not draw power or regen in that coasting situation. I can view this precise energy demand live on my dashboard in my Rivian.
The only difference is that you need to use a second pedal to achieve the braking part of maintaining velocity in a Taycan.
I haven't touched the brake pedal in my Rivian for many hundreds or even thousands of miles, and despite being far bigger, heavier and far less aerodynamic, it is almost as efficient around town, because of the regen system. Yesterday I drove my Rivian 200 miles down a mountain and across California back home without touching the brake pedal a single time. I'd have been on the brakes for 40 miles in the Taycan.

This whole thing to me is no different to the people who bitched about horses being replaced by the first cars, or losing the advance retard controls when that became automated with distributors, or when PDK transmissions became better and more widespread than manual transmissions, or fuel injection replaced carburetors. I've driven tens or hundreds of thousands of miles in both types of EV's and the regen cars were superior and less demanding.
If I want a challenging drive, I will take an entirely different breed of car; if I just want to get there with minimal fuss, I'll take the Rivian.

So yes, you confirm you definitely don't understand but you like one-pedal driving.

It doesn't matter if regen is done by lifting the throttle pedal or brake pedal, regeneration NEVER has 100% efficiency.
Fine.

 

[SpawnyWhippet]

I'm a Rivian development engineer. I definitely understand what one pedal driving is and you haven't anything other than disputing what I wrote without providing any facts.
For the 3rd time Regen cars CAN coast without energy use just like the Taycan.
I'm done here.

 

[f1eng]

I'm a Rivian development engineer. I definitely understand what one pedal driving is and you haven't anything other than disputing what I wrote without providing any facts. I'm done here.

It doesn't matter whether the regen is done in a programmed one pedal driving law on the throttle pedal or using regen via the brake pedal algorithm in neither case is the energy returned to the battery with 100% efficiency.

It is very simple, I explained it many posts ago.
Regen always wastes a bit of energy, coasting does not.

The idea that a 1 pedal solution is more efficient than using the brake pedal to control the back torque depends on the algorithm, could be either way, but is always lossy.

I could understand your point if the Taycan braking was done by friction but it isn't - surely you know that?

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