Regenerative brake

[KLHubb]

The essential question is which regen mode recovers the most net kinetic energy.
Both don't recover 100%, so which mode (regen or brakes) has the least parasitic loss.

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[Jhenson29]

The essential question is which regen mode recovers the most net kinetic energy.
Both don't recover 100%, so which mode (regen or brakes) has the least parasitic loss.

Between Tesla and Porsche? I don’t know. But I’m not sure that’s “the essential” question. It’s a question, for sure. But the essential one?

First, Porsche can recup significantly higher, so even if less efficient (and I don’t know that it is), it has more potential.

Second, the “essential” question also ignores what I’ve stated numerous times in this thread and others. Regen is not itself desirable. It’s preferred to friction brakes.

Third, and probably most important, any difference in regen efficiency is probably largely negligible relative to both the magnitude of applicable duration of motoring efficiency.

 

[Jhenson29]

so which mode (regen or brakes) has the least parasitic loss.

If you really mean difference between applying regen from throttle lift vs brake pedal, there is no difference. Those are just different input interfaces to request the same thing, a negative motor torque. There aren’t different “types” of regen in that sense.

 

[f1eng]

Michael was difficult on a number of topics including throwing up in first gen sims as his brain was so sensitive to tiny timing errors in the visual/physical cueing.

At a Pembury test in 1993 the truckie went out and got lunch at the nearby McDonalds.
Michael threw up on his first lap after lunch and while he was cleaning up one of the guys cut out a McD M and stuck it front and centre of his helmet.

Not something that would happen nowadays, either the testing, self catering or getting away with an unauthorised "mod" to helmet logos.

 

[SHM]

I must say people went a little overboard in this thread, I can in some way agree with people who say coasting is more efficcient than regen.

And of course that is because when you regen, you have heat loss.

BUT: on the other hand, if you coast, you may end up with too high speed and then will anyways apply brake and braking without regen is then less efficcient than regen.

And of course, braking with regen on demand by pressing brake pedal - will regen. But then again, if you have one pedal driving you can also coast. Its just to not move your foot outwards.

Personally I do like 1 pedal driving best.

 

[Vercingetorix]

How do you cover the brake pedal with one pedal driving? Answer is you can’t, which in my book makes one pedal driving inherently less safe. Unless you’re a left foot braker.

 

[W1NGE]

I must say people went a little overboard in this thread, I can in some way agree with people who say coasting is more efficcient than regen.

And of course that is because when you regen, you have heat loss.

BUT: on the other hand, if you coast, you may end up with too high speed and then will anyways apply brake and braking without regen is then less efficcient than regen.

And of course, braking with regen on demand by pressing brake pedal - will regen. But then again, if you have one pedal driving you can also coast. Its just to not move your foot outwards.

Personally I do like 1 pedal driving best.

Umm braking always leads to recuperation and you have no control over that!

 

[whitex]

Personally I do like 1 pedal driving best.

It is a valid preference. I think people in this thread (not necessarily you) have been confusing efficiency vs. preference. Efficiency is defined by tangible metrics. Preference is always relative to whom. From efficiency point of view, 1 pedal can never be more efficient than blended braking, so depends on how optimally the driver operates the accelerator, but it is at best the same. Preferences on the other hand are based on emotions - which one makes you feel better, is easier for you to operate, how important is efficiency, etc. This means there will be people on both sides. The question to car manufacturers of course is ROI in terms of sales from supporting one-pedal driving, blended-braking, or both. Supporting both definitely more expensive in terms of development, testing, and maintenance, so it has to bring a good return to justify doing it.

 

[whitex]

with a Tesla instead, like said posts before, you need to modulate the accelerator pedal because the regeneration is like on/off so you’ll end up reducing the time with generation on and forced to used the brake pedal to come to a stop…

Tesla regeneration is not ON/OFF. It's controlled by the accelerator pedal position. Tesla also added a mode where the car will come to a complete stop with one pedal driving (I think the mechanical brakes automatically engage at stop).

I drove various Teslas over a decade (owned 4, drove rentals and other people's cars) and while I liked the one pedal driving, I didn't like the full stop with one pedal. Maybe it was because my first Teslas did not have the full stop mode, and I always liked the "Creep ON" setting. Mercedes EQS has a blended braking system, but a software emulated one-pedal driving, where the car presses the brake pedal for you when you let off the accelerator (it actually moves without you having to touch it). So even with one pedal driving there are variations that some people might like better than others.

Of all systems that I've tried, I personally prefer the Porsche one best (especially after the 2024 PSM firmware upgrade), but it doesn't mean I hate the others.

 

[SHM]

How do you cover the brake pedal with one pedal driving? Answer is you can’t, which in my book makes one pedal driving inherently less safe. Unless you’re a left foot braker.

I don’t understand the logic behind saying one-pedal driving is less safe because you can still use the brake.

For context, I frequently drive on very steep and narrow roads, often just wide enough for a single car. With one-pedal driving, I can control my speed by easing off the accelerator, which provides a controlled slowdown.

Of course, in an emergency, I’d still press the brake pedal. But how is this less safe than coasting?

When coasting, you’re not slowing down until you actively move your foot to the brake. With one-pedal driving, your speed is already reduced as you transition to the brake pedal. Doesn’t this make one-pedal driving safer, not less safe?

I’m curious to hear thoughts from others who have driven both ways!

 

[Vercingetorix]

I don’t understand the logic behind saying one-pedal driving is less safe because you can still use the brake.

For context, I frequently drive on very steep and narrow roads, often just wide enough for a single car. With one-pedal driving, I can control my speed by easing off the accelerator, which provides a controlled slowdown.

Of course, in an emergency, I’d still press the brake pedal. But how is this less safe than coasting?

When coasting, you’re not slowing down until you actively move your foot to the brake. With one-pedal driving, your speed is already reduced as you transition to the brake pedal. Doesn’t this make one-pedal driving safer, not less safe?

I’m curious to hear thoughts from others who have driven both ways!

It takes time to move your foot from the accelerator to the brake. When I drove a truck professionally we were taught at anytime you are unsure of your surroundings cover your brake pedal. 1/10 of second at 30mph is 4.4 feet. Fractions of seconds matter sometimes.

 

[mlherman]

This is an older thread, but I wanted to log my opinion that Auto-Regen is a very nice feature. I drove a Model S for 4 years before upgrading to Taycan, and I was initially disappointed to lose 1 pedal driving (as I knew it). But now I am completely converted. I prefer coasting most of the time, but Auto-Regen helps me out when coasting means unintentionally closing the gap to the car ahead of me. Makes slow-and-go traffic a lot less tiring, both on the highway and on local roads. Especially since my car (which I bought used) does not have ACC.

 

[F1Ruaraidh]

Sorta. It's ok but it can be a total PITA on the A14 or M25 where you just end up fighting with the car if you try to drive with a smaller gap than the car wants.

Then the hopeless calibration of the throttle pedal (the zero torque point should deepen as you close the gap) means you end up hunting in and out of regen in just the inefficient manner Porsche gave as the reason for having coasting. And, I might add, hunting I've never experienced in any other EV nor from jumping back into my Model S.

Porsche's EV driveability (fahrbarkeit) is utterly hopeless and needs redoing from the ground up.

Model S isn't perfect as the options are inaccessible during driving but it's much better than the Taycan.

 

[f1eng]

Porsche's EV driveability (fahrbarkeit) is utterly hopeless and needs redoing from the ground up.

Model S isn't perfect as the options are inaccessible during driving but it's much better than the Taycan.

My opinion is the opposite but I deliberately never go on congested roads
Tesla designed for commuting and Porsche for the open road!
The Taycan may have faults but driveability is not one of them, for my use.

Edit to add:
I think use case has a huge influence on what we like or don't.
I have adaptive cruise control on my Toyota and in heavy traffic it is a convenience but I only drive in heavy traffic once or twice a year when I make a route planning mistake.
In moderate traffic is is useless and I switch it off, whereas I used normal cruise controll all the time on previous cars. The adaptive cruise was a considerable downgrade for me and a marked inconvenience.

 

[F1Ruaraidh]

My opinion is the opposite but I deliberately never go on congested roads
Tesla designed for commuting and Porsche for the open road!
The Taycan may have faults but driveability is not one of them, for my use.

Edit to add:
I think use case has a huge influence on what we like or don't.
I have adaptive cruise control on my Toyota and in heavy traffic it is a convenience but I only drive in heavy traffic once or twice a year when I make a route planning mistake.
In moderate traffic is is useless and I switch it off, whereas I used normal cruise controll all the time on previous cars. The adaptive cruise was a considerable downgrade for me and a marked inconvenience.

Porsche is just a car and is used as such.

It has clear driveability issues under certain circumstances and that's a problem. Especially when a brand sells itself as being driver centric and the brand of options/configurable cars.

It just needs to be less ideologically driven. I don't want a car that feels ICE, that's why I bought an EV.

Open road, no argument, it's great. Busy roads and town. Poor

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